earth science 2gg3 - natural disasters (mcmaster university)

John Mascotto-Carbone

EARTH SCIENCE 2GG3: NATURAL DISASTERS

INTRODUCTION Instructor – Lisa Leoni Textbook – Natural Hazards and DisastersMark Breakdown Avenue Quizzes: (4/5 @ 10% each) = 40% of final grade Midterm = 25% Exam = 35% No AssignmentsCourse Website www.avenue.mcmaster.ca

o Check this site frequently Course Outline

o Read it carefullyo Located in avenue to learn

Important Dates Midterm: Tuesday, May 24th, 2011 Final Exam: Thursday, June 16th, 2011

NATURAL HAZARDS AND DISASTERSHazards and Disasters Hazard – a phenomenon that causes problems for people

o Something that could happen and we should be aware of Disaster – an event involving a significant number of people and/or significant economic

disasterso Something that has occurred – loss of human lives and economic damage

When natural disasters happen, they have huge impacts on the worldo Tsunami in Japan – killed 280,000 people in around a dayo Hurricane Katrina – 5 billion dollars in damages

Rising number of natural disasters over the past 30 yearso More disasters have happened over timeo On average – 78,000 people die a year from natural disasters

Including millions of dollars in damages What defines a disaster?

o Something that has caused a minimum of 30 deathso In Canada a disaster is - $500,000 in damageso Different countries = different thresholds

What type of disasters are thereo Geophysical Hazards – Natural – things that can’t really be prevented

Earthquakes Tsunami Volcanoes Landslides Asteroids

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http://www.avenue.mcmaster.ca/


o Hydrometeorological Hazards – Natural and Human Created Floods Droughts Wildland fires Weather phenomena Landslides

o Biologically Related and Medical Hazards – Natural and Human Related Is our impact of the world having an impact on natural disasters?Exposure, Sensitivity, and Prediction Exposure – the degree to which a particular hazard or phenomenon occur

o Living in Hamilton and having snow in the winter Sensitivity – the potential degree to which an individual or community could be affected by a

natural hazardo Here in Hamilton we are used to snow and snow storms and we know how to deal

with ito Elsewhere – such as Las Vegas – they do not know how to handle snow or deal with it

Vulnerability – the degree to which a person, community or system is adversely affected by a hazard; Vulnerability = Exposure + Sensitivity.

Risk, Probability and Prediction Risk – the chance or potential for something to happen. Probability – the likelihood or statistical measure that a particular event will occur. Prediction

o Recurrence Interval (return period) – the average number of years between an event of a certain size in a location

Relationships between natural hazards If there is one thing occurs it could lead to other disasters

o Earthquakes can cause Tsunamis which can cause landslides and so onMagnitude and Perception Small magnitude events happen often

o Larger magnitude events happen less often Important to study small events to see if they will lead to big ones

o How they can lead to larger eventsWhy do people live where they are vulnerable to natural hazards? Agriculture: fertile soils

o Floodplainso Volcanic ash

Scenic Viewso Cliffs and hill slopeso Coastal and fluvial areas

Memory of last disaster long forgotten Community established before natural hazard was identified No options

o An economically less-developed community lacks resources to be relocated People just sit and deal with the disasters

Land use planning – Land use restrictions and reserved natural area Problems

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o Citizens feel it infringes on their property rightso Hazardous areas already heavily populatedo Expansion of urban centres into previously undesirable hazardous areas

Mitigation and Adaption Mitigation – taking actions to physically reduce theexposure of the community to the hazard. Adaptation – accepting that the hazard will occur, or that it cannot be completely mitigated or

eliminated; taking actions to reduce the impact and the communities sensitivity and vulnerability.

Approaches to Mitigation and Adaption Affecting the cause: mitigating by reducing the likelihood that the hazard will occur Modify the hazard: mitigating by constructing engineering solutions or relocating people,

buildings and communitieso Walls and dykes to prevent disasters

Modify the loss potential: mitigation and adaptation measures that reduce sensitivity and vulnerability, both economic and social, to a hazard

Spread the loss: adaptation measures to distribute economic loss among a broader group (e.g., taxation, government assistance and charity)

Planning for the loss: adaptation measures to budget for the economic or social cost that a hazard could potentially cause (e.g., emergency plans and insurance)

Bear the losso Deal with it.

Approaches to Natural Hazard Assessments Assessment of the degree of exposure

o (e.g., physical assessment of slope stability) Evaluation of the community’s sensitivity to a hazard

o (e.g., community preparedness – financial resources, education)A complete investigation will consider elements of both: physical assessment and community-based assessment.

PLATE TECTONICS Outline• Development of a Theory • Earth’s Structure • Divergent Boundaries • Convergent Boundaries• Transform Faults • Hotspot VolcanoesDevelopment of a theory Continental Drift 1912: Alfred Wegener

o Thought that at one time the continents were all together and moved apart over timeo Continents all fit together

Had similar trees, rocks, and biologyo However he was incorrect because continents do not simply plow through the ocean

Seafloor Spreading 1960: Harry Hesso Sea floor spreads, creating more sea floor and rockso Determined by magnetic patterns to date the sea floor to see the age

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Ridges – newer rocks Away from the ridge is older rocks

Proof of magnetic properties of rocks **Atlantic Ocean is getting bigger and the Pacific Ocean is getting smaller**Earth’s Structure Lithosphere – rigid outer rind of the earth approximately 60-200 km thick

o Continental Lithosphere Silica rich

Metallic minerals Lower density Thicker crust

o Oceanic lithosphere Iron and magnesium rich Higher density

Asthenosphere - part of the Earth’s mantle belowthe lithosphere that behaves in a plastic manner.

o Convection cells in the asthenosphere cause upwelling that goes up and acts as a conveyer and moves the continents

o **UPPER MANTLE** Crust, mantle, solid outer core and liquid inner core** Most plates are made up of both continental and oceanic crust Between plates there are boundaries

o Convergent Plates that come together

o Diverging Plates that move apart

o Transform Plates slide past each other

Earthquakes caused by this plate activity Volcanoes frequently located on the boundaries between platesDivergent Boundaries Oceanic spreading

o Oceanic ridges (mid Atlantic ridge)o Only place in the world where Ocean plates coming apart is in Iceland where the mid

Atlantic ridge rises above sea level Continental Spreading

o Pulls apart at much slower rates compared to oceanic spreadingo Typically does not form on plate boundarieso Examples:

Basin & Range East African Rift

Area filled with water as the continents spread apartConvergent Boundaries Subduction

o Ocean-continent collision Continent volcanic arc of stratovolcanoes form from the heating of the

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subducting plate and the melting of the overlaying mantle and continental crust (Cascade volcanoes)

The ocean plate will usually slide and go under the continental plate and melts creating a range of volcanoes

Seen in the northwestern United States - Cascadeso Ocean-Ocean collision

Oceanic island arc of basaltic volcanoes Different types of rocks

Continent-continent collisionso Frequently results in the forming of mountains

Too light to go under the earth **Most dense crust goes down – melts and creates volcanoes**Transform Faults Two plates moving and sliding past each other and will create earthquakes

o A lot of friction and sometimes get stuck on one another Example – San Andreas fault in California

o Very prone to earthquakesHotspot Volcanoes Hotspot volcano: an isolated volcano, typically not on lithospheric plate boundary, but lying

above a plume or hot column of rock in the Earth’s mantleo Not associated with a plate boundaryo Origin of formation not completely knowno Magma source: deep mantleo Oceanic crust hotspots

Form basaltic island chains as the plate moves over the hotspot (e.g., Hawaiian Islands)

Continental crust hotspots Form rhyolitic volcanoes (e.g., Yellowstone)

Example – Hawaiian islandso Volcanoes form in the ocean and pour out magma and continue to let the islands growo Eventually they will be eroded away as the hotspots move away

EARTHQUAKES: THE DISASTERSOutline Introduction Earthquake Waves Faults & Causes Locating Earthquakes Earthquake Characterization Ground Motion and FailureIntroduction Where do earthquakes occur? Where do earthquakes occur in Canada? Earthquake magnitudes and human fatalities

o Most deadly known earthquake – Shensi, China 1556

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Magnitude: -8Earthquake Waves Period – the time between seismic waves. Wavelength – the length from crest to crest of a wave. Frequency – the number peaks per second. How do scientists measure earthquakes?

o Seismograph Types of seismographs

o Short-period Seismographs: Record local earthquakes

o Long-period Seismographs: Record distant earthquakes

o Broadband Seismographs: Record both local and distant earthquakes; but cannot accurately measure strong

earthquakes in the direct vicinityo Strong-motion Seismographs:

Record local and very strong earthquakes Earthquake wave types

o Body Waves P waves (primary or compressional): wave shakes back and forth along the

direction of wave travel. Shake back and forth parallel to direction of travel

o Could record these on the other side of the world 8 km/s upper mantle 5-6 km/s continental crust

S waves (secondary or shear): shakes back and forth perpendicular to the direction of wave travel. (Cannot travel through a liquid)

They move up and downo Perpendicular to the direction of travel

4.5 km/s upper mantle 3.5 km/s crust

o **Both waves travel very fast**o Surface Waves - 2 - 4.5 km/s

Move much more slowly Love waves: move side to side

Move side to side Very destructive

Rayleigh waves: move up and down Rolling waves – similar to ocean waves

Faults and Causes Fault types

o Normal fault Occurs when earth is extending (pulling apart) and one will slide down the

othero Reverse fault

Two plates pushing together and one slides up and the other slides down

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o Thrust fault Gentler angle Compression

o Strike slip (right lateral) fault Plates moving fast one another Right lateral fault (left lateral)

Direction that piece of earth shifts towards Elastic Rebound theory

o Elastic Rebound Theory: the theory applied to most earthquakes in which movement on two sides of a fault leads to bending of the rocks until they slip and snap to release the bending strain.

o Stress: the force on a body. Force that’s causing plates to move

o Strain: change in size or shape of a body in response to an imposed stress. Actual change in size and shape to a body

Rocks under stresso Under stress, rocks deform

Can be reversedo When stress becomes so high rocks begin to act like plastico When stress and strains becomes so high the rocks become brittle, break and cause an

earthquakeLocating Earthquakes Earthquake Epicenter

o Where the earthquake occurs in the focus and ‘hypocenter’o Point where the earthquake hits first

From their the seismic waves go outwards Four major seismograph stations in North America

o Denver, Colorado, USo Seattle, Washington, USo Berkeley, California, USo Ottawa, Ontario, Canadao Can use the difference of the P and S waves to determine how far away the earthquake

was from the seismic station Earthquake magnitudes are estimated using nomograph charts

o As the seismic waves come in they can determine when the P and S waves come in and can determine how far they are from the earthquake

o Can also determine amplitude o Can use all this info to determine where and how big the earthquake is

Earthquake Characterization Intensity scales

o Intensity Scales: indicates the severity of an earthquake in terms of the damage that it inflicts on structures and people.

Going into an area and surveying the damage and peopleo Mercalli Intensity Scale: developed in 1902 by Italian seismologist Giuseppe

Mercalli; Modified Mercalli Intensity scales account for various construction practices

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used in different cultures and countries. Roman numerals I-XII Mercalli Intensity Scale maps

Based on observations of people who felt the earthquake Objective descriptions of the level of damage

o Tougher building codes and new developments in construction should decrease future Mercalli Intensity scores.

As we get better at designing more earthquake resistant buildings Mercalli Intensity Scale Maps

o Intensity pattern not circularo Intensity pattern elongated along fault lines

Not one area but breaks out along the fault lineso Larger intensity over areas with loose soft sediment - (e.g., Marina district and

Oakland) Types of land buildings are built on

Buildings built on solid rock get less damage then say buildings built on sand

Magnitude Scaleso Magnitude Scales: measures earthquakes quantitatively, independent of location, and

assigns a magnitude value based on energy released. Looks at the energy that’s been release Richter scale…

o Richter Magnitude Scale (ML): developed in 1935 by Charles Richter; based on maximum amplitude of earthquake waves recorded on a Wood Anderson seismograph.

Logarithmic scale Energy level between Richter scale units differs by 31.5 times (e.g., a

magnitude 6 releases 31.5 times more energy than a magnitude 5 earthquake) Moment Magnitude

o Moment Magnitude (MW): a measure of the total energy expended during an earthquake; depends on its seismic moment determined by:

Rock shear strength How strong are your rocks?

Area of rock broken Average slip distance (offset) across the fault **Takes all of things into consideration and determines the amount of energy

that was released Earthquake of larger magnitude occurs less oftenGround Motion and Failure Acceleration: the rate of increase of velocity;

o The ground accelerates during an earthquake from being stationary to a maximum velocity before slowing and reversing its movement.

o Ground accelerates in speedo So many things can occur from the ground shaking

Avalanches and landslides The more ground that is broken and displaced means that the magnitude must have been

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biggero Largest Earthquake was in Chile in 1960

Magnitude = 9.5, and over 1000 km of ground displaced Surface Rupture Length: the length of a fault broken during an earthquake. Liquefaction: water- saturated sediments jostled by an earthquake rearrange them selves into

a closer packing arrangement.o Escaping water during the repositioning of sediment grains can cause sand boils.o Water moves up and pushes out of the ground and softens the ground and is unstable

for buildingso Sand boils – water pushed out of the ground

Quick Clays: water saturated fine-grained mud deposits in salty water, which are unstable and may easily collapse and liquefy during an earthquake.

o Even a little ground shaking could damage and displace a lot of ground because this type of ground is so unstable

Ice-debris avalancheso Occur in regions where there are mountains with ice caps

Causes ice caps to fall off the mountains and be very destructive Rockslide and Sturzstorms

o Huge rock and landslides

EARTHQUAKES: ASSESSING HAZARD AND REDUCING RISKOutline Building Materials & Oscillations Assessing Seismic Risk in Canada Transform Fault Earthquakes Subduction Zone Earthquakes Continent-Continent Collision Zone Earthquakes Earthquakes within Tectonic Plates Earthquake Forecasts and PredictionBuilding Materials and Oscillations Buildings at different heights swing at different frequencies and also depends on the

magnitude of the earthquake Construction techniques are important to prevent deaths in earthquakes

o Many deaths in earthquakes come from poor building techniques Short building

o Rigid 1-2 storey building oscillates at 5-10 Hz*o Shakes back and forth rapidly (high frequency)o Thus, period is 1/5 to 1/10 = 0.2-0.1 sec

Mid-height buildingo Building oscillates at 0.5-4 Hzo Shakes back and forth less rapidly (intermediate frequency)o Thus, period is 1/0.5 to 1/3 = 2-0.3 sec

Tall buildingo Flexible 20 storey building oscillates at -0.2 Hzo Sways back and forth slowly (low frequency)

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o Thus, period is 1/0 or 5 sec Therefore

o A short, rigid building on soft sediment often does okay in an earthquake. **o Soft sediment vibrates at low frequency (dull thud when hit with a hammer), but

building does noto A tall, flexible building on bedrock often survives better in an earthquakeo Bedrock vibrates at high frequency (rings when hit with a hammer, but building does

not Older buildings are at a risk

o Buildings without proper support are very vulnerable *Period is the time for a single forward and back motion. Hz = Hertz = cycles of back and

forth motion per second **Except for secondary effects such as liquefaction or landslides Base isolation pads

o When the ground shakes the pads keep structures in one piece as they move with the ground and not shake the structure

o Giant rubber pads acting as shock absorbers Assessing Seismic Risk in Canada Seismic Hazardous areas

o Area of highest risk of Earthquake in Canada is Southwestern Canada in the Vancouver area – BC coast

o Other areas of risk are: Montreal Region Northeastern area of Baffin Island East of Atlantic Canada Northern Canada

Western Yukon and Northern Islands of the Northwest Territories Spatial Acceleration areas of Canada

o All coastal regions in Canada and Southern Ontario and Quebeco BC is very prone to earthquakes

Biggest earthquake in Canadian history – 8.1 in Canada’s West Coast, 1949 Canada’s Pacific Coast at highest risk for earthquakes Saguenay, Quebec earthquake – November 25, 1988

o Magnitude = 5.9o Spread out all over Southern Quebec and Southern Ontario into the Northeastern

United States Intensity began to lower the more it moved away from the epicenter

Courtenay-Comox Earthquakeo Spread all over Vancouver Island and BCo Little deaths and damages resulted

Transform Fault Earthquakes San Andreas Fault

o Probability of a 6.7 magnitude earthquake along the main faultso Continental fault that goes right through California

One plate moving north and the other moving south

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o In many cases the rocks are locked into each other and builds up more stress and will result in a much bigger earthquake

o Goes right through the city of San Francisco **San Francisco earthquake**

o 1906o Many buildings were damaged and toppled over due to poor groundo Many fires broke out from broken electrical and gas lines

Two major fires that decimated the city Firefighters could not put out the fire because the water lines also broke

o Waste and decomposing bodies from deaths Resulted from broken sewage lines and deaths caused by disease

San Andreas fault is a very active faulto Earthquakes recorded all the timeo Some earthquakes have not even been recordedo 62% of a large scale earthquake happening in that region soon

North Anatolian Fault, Izmit, Turkeyo Same length and rate of the San Andreas fault o Turkey has had a lot of major earthquakes about the 6.0 magnitude o Patterns of earthquakes

Migratory earthquakes 1999 Izmit Earthquake

o Same building codes as the US but loosely enforced Many buildings collapsed during this earthquake

Due to poor construction practiceso Some buildings sank due to liquefaction

Subduction Zone Earthquakes Very large earthquakes Like the 9.5 magnitude earthquake in Chile, May 22, 1960

o Only 2000 deathso Foreshocks saved many lives as people ran into the streets

Foreshock is like a warning shockContinent-Continent Collision Zone Earthquakes Continent-Continent Collision of Arabian Plate with Eurasian Plate

o **Indian plate colliding into the Eurasian plate**o Caucasus Mountainso Convergence 3 cm/yro December 26, 2003 - magnitude 6.7

Poor construction materials and quality led to widespread collapse & mortalityo Typical Bam, Iran, Construction

**Poor construction caused many deaths in this region** Mud-brick walls or adobe Steel roof girders with a heavy

cement sealed roof Unbraced adobe and brick walls

crumbled during the 2003

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earthquakeEarthquakes within tectonic plates New Madrid, US, 1811-1812

o 3 large earthquakes struck New Madrid, Missouri during 1811 & 1812o Sparsely populated at the timeo Felt as far as the Northeast (Boston, MA)o Recent microearthquakes revealed 3 faultso Recurrence interval approximated at 500 to 1000 years

Charleston, US, 1886o Epicentre 20 km NW of Charleston, NC (Aug. 31, 1886)o Mercalli Intensity IXo Recurrence interval a couple hundred yearso Fault zone near the buried boundary between the Piedmont continental crust and the

Atlantic oceanic crust.Earthquake Forecasts and Predictions Earthquake Forecasts – identifies that a future event will occur in a certain area in a given

span of time with a particular probability. Recurrence Interval – the average number of years between an event Earthquake Predictions – identifies that a future event will occur at a certain time at a certain

place. Indicators of an impending earthquake

o Foreshocks Indicator that a larger event is coming

o Changes in Ground Level May a little ground movement before an actual event occurs

o Seismic Gaps and Migrating Earthquakes Areas where we haven’t seen an earthquake we can guess that there may be an

earthquake in some time Think about the earthquakes in Turkey

o Earthquake Regularity If that area is prove to earthquakes

o Paleoseismologyo Animal Behaviour

Animal reactions and behaviour before an earthquake breaks outo Injections of fluids into the ground?

**1975 – a huge earthquake happened in Chinao Were able to use these indicators to save many lives from a magnitude 7.0 earthquake

**Injection of fluids – Waste was injected into fault lines which caused earthquakes but the earthquakes stopped when Denver stopped injecting fluids

AVENUE QUIZ 1 Released: Thursday, May 5th at 10pm Due: Thursday, May 12th at 7pm Format: 20 multiple choice questions

o Randomized questions

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o Only 1 question at a time – cannot move backward through questions Attempts: will have 3 attempts @ 60min each Coverage: Lectures and Chapters 1-4SAVE ALL ANSWERS AND FULLY SUBMIT QUIZ!!!

TSUNAMI: THE GREAT WAVEOutline Introduction Tsunami Generation

o Earthquake-Generated Tsunamio Volcanic Eruption Tsunamio Tsunami from fast-moving Landslides or Rock Avalancheso Tsunami from Submarine Landslideso Tsunami from Volcano flank collapse

Tsunami Hazards, Warnings and Adaptions Tsunami Threat to Northwest CanadaIntroductionTsunami Tsunami (Seismic sea wave): an abnormally long wavelength wave produced by sudden

displacement of watero Japanese word – means “harbor wave”o Seismic sea waves – because most are caused by earthquakes

Near field tsunami: tsunami that strikes areas adjacent to its point of origino Very close by

Far field tsunami: Tsunami that strikes areas distant from its point of origino Far away from their point of origin

Tsunami Wave Characteristics Long wave lengths

o E.g. 400 km long with an amplitude of 50 cmo Long but not very high

Velocity dependent of water deptho The wave is so big that there is frictional interaction with the ocean bottomo Wave slows down in shallower watero They do move very quickly

At hundreds of kilometers an hour Wave increases its height as the water becomes more shallow near the coast

o As it moves it interacts with the bottom of the oceano In deep waters it touches the bottom less as it would in shallow waters

As it approaches the shore the shallow waters increases the height but slows down

Tsunami Wave Waves steepen and tighten and move forward from the point of displacement Huge volume of water is displaced and moves towards the shore Very destructive waves Run up height and run up distance

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o Normal sea wave – does not reach very far on lando Tsunami wave – because there are up to 400 km of waves it reaches much farther

inland and even run up hills and runs out kilometers inlandTsunami Hazards Lack of warning: difficult to disseminate information between and within countries

o In the Pacific Ocean – Tsunami warning center in Hawaii Can warn other areas that a Tsunami is on the way Areas such as the Indian Ocean do not have such warning systems

o Lack of warning huge issue and leads to many deaths Multiple waves

o Time between waves typically more than 30 minuteso Second or third waves often worse than the first

Contaminated water and diseaseo Can break sewage and power lines and contaminate the water and area

Tsunami GenerationSubduction-zone Earthquake and Tsunami creation 90% of tsunamis are caused by earthquakes Between earthquakes

o Sea level normalo Plates moving between each other with one going under the other

During an earthquakeo Earthquake starts a tsunamio Rocks and plates start to break free from being locked into another plate and end up

moving and displacing the water in the area Minutes later

o Waves spread apartSubsea reverse fault earthquake and tsunami creation Sea surface pulled down and comes up

o Waves just go up and down in both directions Waves move in both directionsSumatra Tsunami – Indian Ocean, December 26, 2004 – most destructive and recent tsunami Caused by 9.1 magnitude earthquake in the subduction-zone between the Indian plate and

Burma plateo Very large magnitude – plates probably locked for hundreds of years and when they

broke apart they created a large tsunami 3rd largest earthquake since 1900 Caused 15-meter offset Paleoseismic studies show that giant seismic events occur every 230 years

o Two plates building stress for 230 years, and broke creating a huge earthquake and tsunami waves

In the Indian Ocean – so there was no warning for the tsunami Tsunami waves generated by this event rose 10 meters or more above sea level Knowledge of this tsunami was able to save 1500 lives during this incidentChile Tsunami – May 22, 1960 Caused by a magnitude 9.5 earthquake in the subduction zone along the coast of Chile

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o Largest magnitude earthquake ever recorded 2000 people killed in Chile, 5700 people killed around the Pacific Ocean

o Tsunami stretched out all over the Pacific Oceano Hilo, Hawaii – 61 deathso Japan – 185 deaths

Ground samples still show evidence of the 1960 Tsunamio Soil cores – show sand deposits from the 1960 Tsunami

Tsunamis traveled afterwards across the Pacific Ocean and even after the subduction zone earthquakes in Alaska in 1964

o Also killed people in Hawaii and prompted the establishment of a tsunami warning system

Hakkaido, Japan – July 12, 1993 Caused by a 7.8 magnitude earthquake on a thrust fault Inudated the small island of Okushiri

o 200 deathso $800 million in damages

Volcanic Eruption Tsunami Volcanoes on the ocean floor which can cause a tsunami 5% of tsunamis are caused by volcanic eruptions

o Collapse of a large volcanic caldera located near sea level can pull a large volume of water and generate a tsunami

Volcano under the ocean – part of it can collapse downwards and causes a large displacement of water

o Submarine volcanic eruption can drive sea water upward and generate a tsunami Volcano underwater erupts and discharges large amounts of material which

displaces water These types of tsunamis impact only the local area while earthquakes-generated tsunamis can

displace a large volume of water and create larger tsunamiso Tsunamis not as big when caused by volcanoes

Exampleso Krakatau, Indonesia – August 27, 1883o Tambora, Indonesia – 1815

Tsunami from Fast-moving landslides or rock avalanches ~1% of tsunami are caused by landslides or rock avalanches

o Very rare for a tsunami to be caused by this These types of tsunamis are created by fast-moving landslides (sediment) or fast-moving rock

avalanches (broken bedrock) falling into the ocean and displacing a large volume of water.o Mountain range or steep slope and a large amount of material falls into a body of

water displacing water and causing a tsunami Size of tsunami waves based on the mass of the material and its gravitational energy.

o Depends on how much material fell in the body of waterLituya Bay, Alaska – July 9, 1958 Tsunami generated by a rock avalanche released by a 7.3 magnitude earthquake. This gigantic tsunami wave was 150 meters high and surged 524 meters above sea levelTsunami from Submarine Landslide

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Pretty much the same thing except it happens under watero But not as big as above ground rock avalanches

Because of the gentle slopes that exist underwater ~5% of tsunamis are caused by submarine landslide Submarine landslide generated tsunamis are typically not as large as ones generated by

landslide/rock avalanches from above sea level because of the gentle slopes of the ocean floor.

Examples: Storegga Slide 8,100 years agoo Tsunami-laid sediment (TLS) found above sea level on the Shetland Islands, Norway,

and Scotlando TLS consist of mud fragments ripped from the sea floor and layers of well-sorted sand

Burin Peninsula – November 18, 1929 Tsunami generated by a submarine landslide that was caused by a magnitude 7.2 earthquake

in the Gulf of the St. Lawrence. Tsunami killed 29 people on the Burin Peninsula and Cape Breton Island. Submarine landside created turbidity currents, which broke the transatlantic cable.

o Cutting off communication to Europe for some period of timeTsunami from Volcano Flank Collapse < 1% of tsunamis are caused by volcano flank collapse.

o Very rare Can be large tsunamis but do not stretch out that far Can produce large near-field tsunamis Examples:

o Hawaii Islands Volcanoeso Canary Islands Volcanoes

Collapses in HawaiiTsunami Hazards: Warnings and AdaptationsTsunami Arrival: The Hazard If the trough arrives on shore first, all the water runs away from shore providing some

warning Can be hours between tsunami waves First wave often not the largest Coastal areas surrounded by offshore coral reef can provide some protection by forcing the

wave to break on the reefTsunami Warning Near-field Tsunamis

o Arrival of tsunami less than 30 minutes after tsunami triggero People need to be aware that earthquakes and such could cause a tsunami

Better education on tsunamis Far-field Tsunamis

o Travel time of tsunamis in the Pacific Ocean can be accurately calculated based on seismograph data and topography of the ocean floor

Sensors at the bottom of the ocean and can send signals to warn surrounding areas

o Tidal sensors and ocean-bottom sensors can detect waves as they move across the ocean

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o Cannot forecast the actual height of a tsunami wave Can only know that a tsunami is coming but not know how big it will be Can’t predict how high they will be

Adapting to Tsunami Hazards Land-use zoning

o Try to prevent building communities in areas that are vulnerable to tsunami waves Engineering structures to resist erosion and sour

o Coastal defense walls to stop tsunami waves Orient streets and buildings at right angle to the waves

o Build in a certain way to structures won’t be hit head on by waves Well-rooted vegetation

o To slow down the waves or keep it from going more inland Seawall with stairway evacuation route used to protect a coastal town in Japan. Water gate used to protect Okushiri Island, Japan. Gate automatically closes within seconds

after earthquake shaking triggers its seismic sensors.Tsunami Threat to Northwest Canada Huge tsunami-flattened forest, are now below sea level because of displacement during an

earthquake of the coastal bulge offshore. Sediments left behind can show ancient tsunami zones that have happened in the past and be

an indicator that that zone is vulnerable to tsunamisTsunami from Cascadia Subduction zone earthquakes Cascadia Subduction zone located 1,200 miles offshore southern British Columbia Sequences of Tsunami-laid sediment (TLS) indicate historic tsunami impacts along the

Pacific Northwest coastlineo Mud – contains the remains of marine plantso Tsunami –laid sando Peat at the base – consists of partially decayed saltwater marsh plants

An ancient Sitka spruce forest in the bay at Neskowin, Oregon, was felled by a giant tsunami following a large subduction-zone earthquake of 1700.

o Destroyed vegetation and laid down tsunami sentiments Vancouver Island

o Has a history of tsunamis and is a very tsunami vulnerable areao Area of high tsunami risk on the western sideo Lower risk on the eastern side

Things to consider – Plate boundaries all along the Pacific Northwesto Plates are also locked and have bulged out and eventually will break

Resulting in a tsunami and major earthquakeJapan’s Earthquake and Tsunami March 11, 2011 Magnitude 9.0 earthquake

o Plates were locked for a few hundred years and when they snapped they created a huge earthquake and tsunami

Subduction zone earthquake between the Pacific and Eurasian plates Generated a tsunami that swept across the Pacific Ocean

o Everyone was warned in Hawaii

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o Did end up hitting North America’s West Coast – killing one person Current casualty estimates

o Approx 15,000 deathso Approx 5,000 injuredo Approx 10,000 missing

TSUNAMI VIDEO: ‘JAPAN’S KILLER QUAKE’ Much of the coast has sunk by as much as 1 meter March 11, 2011 – 2:47pm Japanese time – earthquake hits Japan’s east coast P-waves – 4 miles a second Coastal city Sendai – just 80km from the coast

o No warning for S-waves that shake the ground S-waves slow but very damaging

Northeast Japan – descending into chaos Earthquake hits the Fukashima nuclear power plant

o Intense heat of the reactors does not dissipate – reactor core still very hoto Reactors stopped and no power to cool the reactorso Plant survives earthquake intact

Before earthquake – nothing larger than a 8.4 magnitude Source of disaster – 62 miles from Japan’s coast and 4 miles under water

o Japan (Eurasian plate) while the Pacific plate crashes and goes under it and locked for a long time creating a lot of stress

100 seconds since the fault line slipped – S-waves reach as far as Tokyoo City has 60 seconds warningo Quake lasts 5 minutes

Earthquake began but did not stopo Kept getting bigger and bigger

Frequent characteristics of earthquake – liquifactiono Loosely packed ground easily becomes liquefied and water emerges

For centuries the Pacific plate goes down under the Eurasian plate and springs back by the quake unleashing a vast amount of water that became a tsunami and slammed into Japan

o One side of the wave goes across the Pacifico The other side goes right into Japan’s East Coast

Waves moving at 500 miles an hour races to Japan within minutes Huge shoreline was exposed and a wall of water was built up and the first wave arrives in

Japano No clear pattern as to where the tsunami strikes

First hits the North, then the south, then the North again Height an intensity varies from town to town

Layout of the land helps determine how a tsunami behaves 3:15pm – waves hits a northern town Okanato

o Time scale that they had to react and prepare for a tsunami 15 minutes later the tsunami hits Sendai

o City is mostly farm, low lying and flato Airport is overwhelmed in minutes

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Next wave hits Miyako coast – 110 miles from Sendaio Much more prepare for a tsunami and have built a sea wall and defenses for the

tsunamio Better warning system

Saves a lot of lives o Tsunami easily breaches the coastal defenses and its high walls are uselesso Tsunami is 30 feet high

So why did the 30 foot high wall fail? Because the earthquake caused the coastal areas to drop by several feet

and made the town much more vulnerable Fukashima – shut down nuclear power plant is exposed

o Coastal defense descended and water crashed into the power plant shutting down the reactors cooling system

Batteries take over to cool the reactors but only have an 8 hour chargeo Japan on a path to a nuclear crisis

All that water that hit Japan is now sucked back into the seas bringing with it all that brought down

o Ocean is a huge mass of currentso Large whirlpools are formedo Many people dragged out to sea

At night – fires rage across the wasteland Hawaii – tsunami warning center on full alert

o First big ocean crossing tsunami in over 40 yearso Readings suggest that tsunami is 3 feet higho Evacuation order in Hawaii

No deaths recorded in Hawaiio Wave finally hits Hawaii and is 3 feet high as predicted and surges the island for over

an hour Tens of millions of dollars in damage Much more warning period for people to get to safety

Tsunamis are unstoppable but can be trackedo Scientists effectively warn the world with their accurate predictions

Tsunami goes towards the US and is declining as it moveso Now smaller and weaker hits the Coast of Californiao People are much more prepared and warned

One person dies Japan – crisis continues to escalate

o Many areas are flooded and many fear that bodies will be exposed in local areas In some areas boats, ships, trucks and cars are pushed inland and topped on top of buildings

o Entire towns are flowed ino Forms a massive debris glacier that kept pouring in

Some towns virtually wiped off the map with tens of thousands of people missing 25 miles from the coast rescue workers are deployed and search for bodies Within days scientists gather more data on the earthquake and tsunami than any other disaster

in history

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30 million people in Japan live near the coast and a large population of Japan in vulnerable In the week after the earthquake there are over 500 earthquake aftershocks that rock Japan As the earth’s crust shatters it creates other earthquakes and problems elsewhere

o Leading to aftershocks Aftershocks take its toll on a frightened population

o Every aftershock leads to another one Hundreds of thousands are homeless

o Temporary shelters become full Main highways are empty

o Country has come to a halt Fukashima nuclear problems become worse

o No power and no cooling of the reactorso Immense heat creates hydrogen that explodes o Helicopters try and dump sea water on the reactors in an attempt to cool them but it

does not work Earthquake has now stressed neighboring parts of the plate boundary

o Stress relieved from an earthquake does not go away but goes somewhere else Another major earthquake is due to happen in Japan again and may directly affect Tokyo

o Tokyo happens to be a very densely populated and therefore a lot is at stake and the city is very vulnerable

Major lessons learned in Canada and the USo Cascadia – large fault line from Vancouver Island to Californiao Same issues such as Japan and therefore just as or even more vulnerable to the same

earthquake and tsunami that Japan experienced Is Canada and the US prepared for what has happened to Japan

VOLCANOES: ACTIVITY AND HAZARDSOutline Introduction Basalt Flows and Shield Volcanoes Cinder Cones and Pyroclastic Material Stratovolcanoes Rhyolite Domes Eruptions & ExplosivityIntroduction Volcano: a mountain formed by the products of volcanic eruptions through which lava, ash

and gases are ejectedo Not formed through normal mountain formation processes of continental to

continental contact Magma: molten rock beneath the earth’s surface Lava: magma that flows out onto the ground surface

o Once magma goes above ground it is lavaVolcano and Lava Types (Viscosity, Silica Content & Eruption Style) Viscosity: the resistance to flow of a fluid because of internal friction. (i.e., molasses has a

higher viscosity than water.)o **Water flows easier than glue**

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o Higher Silica Content – more rigid the lava is Higher Viscosity

Attracts gases and steam more More Explosive

That’s when all the gases and steam can explode outwardso Lower Silica Content

Lower Viscosity Gases and steam are able to escape easily

Less Explosive Basalt: a black or dark fine-grained volcanic rock. It has a silica content of approximately

50% and low viscosityo Quiet eruptionso Most iron and magnesium rich rocks

Andesite: a fine-grained volcanic rock with a silica content of approximately 60% with an intermediate viscosity

o Rocks get harder, moderate iron and magnesium contento Explosive eruptions – more than basalto Found in stratovolcanoes

Rhyolite: a light-coloured, fine-grained volcanic rock with a silica content of approximately 70% and high viscosity. Generally erupts as volcanic ash and fragments

o Highly explosive – violent eruptionso Found in rhyolite domes

Products of Volcanoes Lahar – volcanic mud flowBasalt Flows and Shield VolcanoesBasaltic Lava Forms Pahoehoe Flow: basalt lava with a ropy or smooth top.

o Basalt lava with smooth topo Do not move quickly and easy to out walk if one is coming in your direction

Aa Flow: blocky basalt lava with a ragged, clinkery surfaceo Bulky basalt lava with jagged surfaceo Very sharpo Flows slowly and gets chunky

**Top part of lava cools down with inner lava is still flowing**Flood Basalts Flood Basalt: a broad expanse of basalt lava that cooled to fill in low-lying areas of the

landscapeo Never actually seen but have appeared in geologic recordso Theories that these have caused mass extictions in the past

Basalt Volcanoes Along Ocean Ridges At oceanic spreading centers hot mantle rock rises, and as it nears the surface, it partially

melts erupting along the ridge as fluid basalt flows and pillow basalt formations.o Iron and magnesium rich and forms more ocean flooro Cool on the outside but liquid in the inside which forms little pillows on the ocean

floor and elsewhere

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Shield Volcanoes Shield Volcano: an extremely large basalt-lava volcano, such as those in Hawaii, with gently

sloping sides.o Massive large scale volcanoes but very gentle slopeso Lava erupts in three main rift zones

Characteristics:o Low viscosity basalt flowso Gentle slopeso Large sizeo Lava erupts from three main rift zones

Keeps building up over time creating an islandMauna Loa and Kilaulea, Hawaii Oceanic Hotspot Volcano

o Volcanoes that don’t follow the plate tectonics Stages of activity

o 1.Eruptions below sea level build a broad volcano base.o 2.Basalt lava flows build up the mass of the volcano above sea level.

(e.g., Kilauea) Massive

o 3.Eruptions become smaller and less frequent as the volcano moves off the hotspot (e.g., Mauna Loa)

Quiet and frequent eruptionso These volcanoes are constantly erupting but are not violent and the people are sure to

not get too close to them resulting in few to no deaths The Big Island of Hawaii; Mauna Loa, Mauna Kea, and KilaueaMount Etna, Sicily, Italy Most active volcano in Europe

o Mixed history so not completely a shield volcanoo May be a shield and also a stratovolcano

Characteristics of both a shield and stratovolcano Actively erupting since 1992

o Erupts basalt lava continuously and periodically erupts pyroclastic debris in more explosive eruptions

Characteristics of shield and stratovolcanoCinder Cones and Pyroclastic Material Cinder Cone: a cone-shaped hill consisting of volcanic debris (pyroclastic material) ejected

from a vent Characteristics:

o Composed of sand-sized pyroclastic debriso Small, explosive eruptionso Steep slopes

Different types of pyroclastic but most common in cinder cone Pyroclastic: fragmental material blown out of a volcanoPyroclastic Materials Pyroclastic: fragmental material blown out of a volcano (i.e., tephra, cinders, and bombs)

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Tephra: fine materials (dust, ash, and cinders) produced by volcanic action. Cinder: pyroclastic particle of sand size. Lapilli: a particle of volcanic ash between 2 mm and 6mm across. Bomb: a mass of liquid or partially solidified rock that is ejected from a volcano

o So when that gets ejected its not solid rock so it deforms Block: a mass of cold, solid rock ejected from a volcano. **Parcutin volcano in Mexico – small cinder cone volcano with small eruptionsStratovolcanoes Stratovolcanoes: large steep-sided volcanoes consisting of layers of ash, fragmental debris,

and lava. Also called composite volcanoeso Common image of volcanoes

Characteristics:o Contains both pyroclastic material and lavao Intermediate in size and slope angleso ~1000 – 4000 m high and 10-30 km wideo Viscous lavas (high silica content) and violent eruptions and eruptions consisting of

pyroclastic debris and pyroclastic density currents Leads to quite violent eruptions

Pyroclastic Density Currents Pyroclastic density currents (PDC): high-velocity, high-temperature, high-density flow or

surge of volcanic tephra, gases, and debriso Very fast, very hot, incinerate everything in their patho Form in violent eruptions of stratovolcanoes

Stratovolcano Lava Types Several types of lava are erupted from stratovolcanoes around the world including andesite,

dacite, and rhyodacite lavas. These lavas are more viscous because they contain more silica (making them more rigid).

Silica Content:o Andesite < Dacites < Rhyodaciteso Produces a more violent eruption

Cascade Mountains Mountain range in Pacific Northwestern United States extending from Washington state to

Californiao Large range of volcanoes and volcanic eruptions

One plate moving under another in divergent zones – subduction zoneso As one plate melts it creates magma and steam which can create a volcanoo Violent eruptions

Mount Saint Helens – active volcano in Cascadia range Famous volcanic eruption

o Major explosion Erupted on May 18, 1980, 8:32 am

o Largest volcanic eruption in North America in nearly a centuryo Formed a crater in the mountain about one mile wide

Mount Saint Helen, eruption sequence – stratovolcano – entire side of the volcano blasted offo A growing bulge of magma developed under the mountain

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Slow moving and pushed the rocks out in a bulge that appeared in the side of the mountain

Earthquake – magnitute 5.1 occurred – which had the bulge break apart Which then caused a major eruption

o A landslide by the bulge exposes the magma and it releases Side of the mountain collapsed

o Followed by a lateral blast Entire side of the mountain was blasted off Destroyed entire forested area in the area

o Then a blast eruption column Lahar – all that sediment that was on the side of the mountain was very loose and was able to

easily flow down the side of the mountain Hot ash-laden gas boiled out of the vent, expanding into the cooler surrounding air After the eruption the crater was much larger Lateral blast caused many trees to fall in the area Lahar: a mudflow associated with volcanic action or involving volcanic materials

o Huge mounds were left by the May 18 lahar that raced down the Toutle RiverMount Mazama (Crater Lake) – even bigger than Mount Saint Helen Mount Mazama, Oregon Erupted approximately 7,000 years ago forming Crater Lake

o All it left was a crater Estimated to have produced 35 times more debris than the 1980 Mount St. Helens eruption

o Massive Wizard Island is the new volcano that started growing 1000 years ago from the floor of the

Mount Mazama caldera.o Starting to built up again over time

Crater Lake is the caldera depression formed when Mount Mazama erupted. Were able to determine this explosion through pumice rock and geological recordsRhyolite DomesRhyolite Volcanic Domes Rhyolite Dome: volcanic dome composed of rhyolite and rhyodacite.

o Most silica rich lava producing explosive eruptions Giant Rhyolite Volcanoes: Very explosive eruptions with high rhyolite viscosity lavas; forms

gentle sloping flanks.o So silica rich that it moves slowly and only pushes rocks making bulges but eruptions

are violent explosions A huge bulge was formed by a rhyolite dome growing a few weeks before the May 1980

eruption of Mount St. Helens The surface above an erupting rhyolite magma chamber subsides to make a caldera during the

eruption of a giant PDC flow. It domes again as new magma refills the magma chamber.o Eruption of rhyolitic ash flows from ring fracture: partial evacuation of magma

chambero Caldera collapse along ring fracture zone

Rock surface can collapse on itselfo Resurging doming

Still an active zone

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o Late extrusion of rhyolite along ring fracture zoneYellowstone Caldera Resurgent Caldera: A huge collapse depression at the Earth’s surface that sank into a near-

surface magma chamber during eruption of the magma.o Surface collapses in on itself but since the area is still active it rebuilds itself

The Lava Creek tephra erupted 640,000 years ago as the immense Yellowstone Caldera collapsed

o Largest known eruption Lava Creek tephra from the Yellowstone Caldera

o Takes up most of Western United States – affected a very large areaEruptions and ExplosivityMechanisms of Volcanic Eruptions Steam separating from magma opens bubbles

o Magma moving towards the surface As the bubbles grow, the magma begins to froth. That decreases the pressure on the magma

below, launching a chain of reactions of increasingly rapid bubble formation that lead to an explosive eruption

o As it comes up they make more bubbles and spews outo As it spews out theres less pressure on the magma below creating more bubbles

Which late creates a large eruptionMagma Composition (Melting Curves) Water saturated magma (rare)

o Melting curve moves to lower temperature (at higher pressure) if more water is available

Common subduction zone magma (e.g. 2% water by weight)o Deep within the earth’s surface it can be molten and melting rocko As the temperatures change and pressures decrease it can remain melted rock will cool

and crystalize Dry magma (most basalts)

o Melting curve moves to higher temperature (at higher pressure) Injection of Basalt magma into a rhyolite magma chamber

o Injection of basalt magma into granitic magma chamber Creates heat which leads to bubbles an can be released in a violent eruption

o Gas vesicles nucleate in and around inclusions Volatile saturation and pressure buildup; convection

o Eruption Disaggregation and brecciation of inclusions

Volcanic Explosivity Index The Volcanic Explosivity Index (VEI) shows the relative magnitudes of eruptions Rating based on the amount of tephra released – material released in km3

Types of Eruptions Fissure Eruptions: Volcanic eruption from fissures, rather than from a constructed volcano or

coneo Rift in earth’s surface where magma comes out

Strombolian Eruptions: Frequent mild eruptions of basalt or andesite scoria, typically forming a cinder cone

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o Typicall form cinder cones Surtseyan Eruptions: Submarine eruptions of a basaltic volcano

o Under water eruptionso Kind of explosive because they interact with the water

Peléan Eruptions: A large, tephra-rich eruption that typically produces pyroclastic density currents

Plinian Eruptions: Extremely large eruptions that involve continuous blasts of tephra and pyroclasitc density currents (ex. Mount St. Helens)

o Extremely large eruptions Yellowstone Eruptions: A large eruption of a rhyolite dome volcano

o Very large eruptionsVolcanic Precursors (Eruption warnings) Harmonic Earthquakes

o Looking at earthquakes which can be measured Tiltmeter

o Measures the slope angle or bulge of a volcano Thermal and Magnetic Measurements

o Measuring the tempterature of the mountaino Volcano less magnetic when there is an eruption coming

Chemical Analysiso Chemical analysis of the mountain

Volcanologists sampled gases on Mount St. HelensTiltmeters A tiltmeter measures the changing increase in slope on the volcano flank as the bulge grows When rising magma gets close enough to the surface, it often pushes the overlying rock ahead

of it to create a bulge in the flank of the volcanoo Measuring the angle of the bulge of a volcano close to eruption or suspected of

eruption

VOLCANOES: WHEN ERUPTIONS OCCUROutline Introduction Lava Flows Tephra and Volcanic Weather Pyroclastic Density Currents Lahars Volcanoes under Glaciers Harmful Gas Emissions Weather and Climate Volcanic Hazards in CanadaIntroductionHistorical Deadly Volcanic Eruptions

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Historical Eruptions and Hazardous Results

Causes of Deaths Resulting from Volcanoes since circa 1750 Famine and Disease – 30%

o Combinations in regions where volcanoes caused tsunamis, or ash was released that chokes out living things in the region

Tsunami – 25% PDC – 20% Lahar – 20% Other – 15%Lava Flows Heimaey harbour, Iceland in 1973, is a pumping station used to cool the lava flow What do you do when lava flows at you?

o Heimaey Harbour was able to control lava flows by pumping sea water on the lava as it approached to stop the flow of lava from blocking their harbor

Tephra and Volcanic WeatherTephra Tephra: fine materials of dust, ash and cinders produced by volcanic action

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o Tephra from Rabaul volcano, Papua New Guinea, in September 1994, collapsed the roof of the building on the left and thickly coated the roof on the right

o When it reigns down it piles up and can collapse on roofs Even worse and heavier if it is wet

Volcanic Weather Volcanic Weather:

o Higher temperatures above an erupting volcano draws in outside air that rises and cools. Moisture in the air condenses to form rain and stormy weather

As air gets drawn in it rises and condenses which can caused lightning and rain creating its own weather system

Pyroclastic Density Currents Pyroclastic Density Currents (PDC): dense mixtures of hot tephra and superheated gases that

pour rapidly downslopeo Very hot, move quickly, and incinerate everything in their path

Welded Tuff: ash from a hot PDC that is hot enough when deposited that the particles fuse together to form a solid rock

o Pyroclastic density currents flowing downhill The directed blast of the May 1980 eruption of Mount St. Helens stripped and flattened trees

on the windward side of a hill and snapped off their tops on the leeward sideo The Flow was going NORTH

Very destructive and killed everything in its path One explanation for the movement of hot PDCs over water is that the dense part of the PDC

sinks as the lighter part skims over the water surfaceo More dense then air and flow downslope and destroy everything in its patho Most dense particles flow down into the water and can kill aquatic life and go over

large bodies on water An energy line sloping from the top of the heavy “gas-thrust zone” of an eruption can

estimate the height of the hills that might be surmounted by a PDC from a stratovolcano eruption

o Energy will indicate what sort of hails and how far PDCs will go Mechanism of PDCs

o Collapse of Dome with or without gas explosionso Landslide of bulge releases pressure on magma, and initiates eruptiono Continuous eruption with continuous or intermittent column collapseo Magma rises into vent with resulting collapse

Looking at history of area to determine what eruption can be expected in the regiono Looking at sediment layers containing tephera –fall deposits

1991 – Mount Pinatubo erupted and PDCs filled up the nearby riverMount Pelée, Martinique, 1902 Started erupting in early spring of 1902 with several surges of PDC. After a lahar flow killed 40 people at a rum distillery on the northern edge of St. Pierre on

May 5th, some people evacuated and went to Fort-de-France.o Signaled that people should evacuated but people stayed

On May 8th a PDC rushed down Mount Pelée at an estimated speed of 190 km/hr and completely wiped out the city of St. Pierre except for two survivors.

28,600 people were killed by PDCs and 400 people were killed by lahars

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Today, St. Pierre has been rebuilt and has 5,000 inhabitants.o If volcano explodes again they are at high risk

Lahars Lahar: a mudflow associated with volcanic action or involving volcanic materials

o Along the side of the volcano all that sediment is fine grain and is loose, and if water is added it can move very quickly down hill and created huge deposits of mud

Nevado del Ruiz, November 13, 1985 1984 Nevado del Ruiz started to show signs of activity

o Geologists went into the area to investigateo Released a hazard map but created widespread fear so it was taken away

A hazard map for the area was released to the public a month before eruption, but it was withdrawn because of objections regarding property values and fear-mongering.

After the initial eruption on November 13th the towns, Manizales and Chinchina, received warning from the press and the local government; but Armero received no effective warning and lost 22,000 of its inhabitants.

Vesuvius Mount Vesuvius erupted in 79 AD burying Pompeii with pumice and ash and burying

Herculaneum with a series of PDCs. Both PDCs and Lahars Killed 3,500 people Buried two towns – one is the famous Pompeii and the other HerculaneumVolcanoes under GlaciersTuya Tuya volcanoes: flat-topped volcano formed by an eruption under a glacier

o Glacier cover the volcano and the area is flatJökulhaup Jökulhlaup: rapid discharge of water from an ice-dammed lake, typically resulting from a

volcanic eruptiono Water will stay there until the glacier fails – rapid discharge of water from a lake

Harmful Gas Emissions – magma has a lot of gases in it Carbon dioxide

o Deadly in high concentrationso Concentrates in depressionso Colourless and odourlesso Can escape in faultlines and not just volcanoes

Sulphur dioxideo Harmful to animals and plants even in low concentrationso Reacts with oxygen to form sulphur trioxide which in turns reacts with water vapour

and forms sulphuric acid.o Molecules hang suspended in the atmosphere for months, blocking sunlight and

altering the climate. Hydrogen Sulphides Chlorine FluorineWeather and ClimateWeather and Climate Effects

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Eruptions that inject large amounts of sulphur dioxide into the stratosphere reflects solar radiation causing decreases in air temperature

o Can lead to global cooling 1982 El Chichón and 1992 Pinatubo eruptions both dropped summer temperatures by 0.5oC 1883 Krakatau Eruption dropped summer temperatures by 0.3oC The 1816 eruption of Tambora volcano in Indonesia caused cooler temperatures globally.

Snow remained on the ground all summer in New Brunswick.Mount Pinatubo, Luzon, Philippines, 1991 – larger eruption Geologic mapping showed PDC flows 600 years prior to the 1991 eruption across densely

populated areaso Starting noticing little earthquakes in the region

Based on small earthquakes, sulphur dioxide emissions, and PDCs, volcanologists predicted on June 5th that a major eruption would occur within a 2 weeks time frame.

o All predictions came true June 12, 1991 the culminating event began with a lateral blast and a huge plume of steam and

tephrao Much larger than the Mount Saint Helen eruption

Intense rain caused by Typhoon Yunya and volcanic weather created wet tephra and laharso Collapsed a lot of roofs

350 people were killed, however, warnings and evacuations saved tens of thousand of liveso Could have been worse but thanks to geologists many people were saved

Volcanic Hazards in Canada Mount Edziza Volcanic Complex

o Spectrum Ridgeo Armadillo Peako Ice Peako Mount Edziza

Garibaldi Volcanic Belto Bridge River Complexo Mount Garibaldio Mount Priceo Mount Meagero Squamish Volcanic Field

Mount Churchill **Mount Churchill. The hachured area is the caldera, which is the proposed source of the

White River Tephra**o Can produce violent eruptions and can be very destructiveo Evidence of eruptions

Has erupted in the past and could happen again Mostly in the west coast and Yukon area If these volcanoes were to erupt it would affect air traffic in the region

SLOPE FAILURE: FALLS, SLIDES AND, FLOWSOutline Introduction

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Types of Slope Failureso Falls & Toppleso Translational Slideso Rotational Slides (Slumps)o Creepo Debris Flows, Grain Flows, & Mud Flowso Sturzstroms (Rock Avalanches)

Hazard Mapping & AssessmentIntroductionFactors Controlling Downslope Movement of Materials Slope Angle

o Shear Stresso Normal Stress

Critical Angle of Repose Cohesion & Water Saturation

o Surface tensiono Water pressure

Material StrengthSlope Angle Shear Stress (t): stress resulting from application of force parallel to a surface (force pulling

the boulder/grain down slope)o Trying to pull material down parallel to the slope

Normal Stress (s): component of stress perpendicular to the Earth’s planar surface (force keeping the boulder/grain from moving)

o Perpendicular to the slope and tries to hold it up Balance between friction & gravity. Sheer stress proportional to the slope of the angleCritical Angle of Repose Critical Angle of Repose: maximum angle at which sediment particles can stand without

falling. Critical angle of repose depends on: (different factors)

o Grain Size- Small rocks and large rocks – large rocks can stay put longer as they stack up

o Grain Angularity- Rounded grains < Angular grains

o Moisture content- Dry sediment typically is less stable than damp sediment

Too much water will also make it unstable- Oversaturated sediment becomes less stable

Cohesion Cohesion: the attraction between small soil particles that is provided by the surface tension of

water between the particles. Surface Tension: tension in a surface layer of water that causes it to behave as an elastic

sheet. (i.e., cohesive film water creates when put between two sheets of glasso This is how you can build a sand castle

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Water Pressure Water Pressure: the pressure of water spaces between grains in the ground.

o In saturated sediment, the pore spaces between grains are completely filled with water.

o More water on a slope increases the water level in the sediment and the pressure in the pore spaces at depth. Can lead to slope failure

Material Strength Loose, poorly cemented, dry material is weak

o Pure dry sand is fairly weak and can fail Solid, well-cemented material is stronger Weak between sedimentary layers & along well developed fractures

o Weakness in surface and area where rocks can fall off, topple or slide *Filling a reservoir behind a dam raises groundwater in adjacent slopes, often leading to

sliding into the reservoir.o Adding water

**Installation of a perforated drainpipe can lower the water table and reduce the chance of sliding.o Pipe that is shoved into a hill and allows water to drain out and reduce water table

allowing the water to drain out so there is a less of a chance of a slide ***Perforated drainpipe in a shale road cut on U.S. Highway 101 north of Garberville,

California. ****Black plastic wrap on hills can prevent water from getting on them causing a land slideTypes of Slope FailuresFalls and Topples Fall: a slope failure that involves vertically downward motion under gravity of a block

without internal deformation or rotation. Topple: a slope failure that involves vertically downward motion under gravity of a block

without internal deformation, but with rotation.o Steep cliff bases the prime area for this type of events to happen

*Potential for rock falls along the British Columbia Sea-to-Sky Highway between Vancouver and Squamish.

Frost Wedging Frost Wedging: splitting of rock through pressure exerted when water freezes.

o Freezing water expands by 9.2%.o Coastal areas prone to frost wedging where temperature oscillates around the freezing

point.o Freezing and unfreezing occurring allowing a wedging over and over again which splits the

rocks in half which can fall or topple off Large masses of rock that can fall off and is a major hazard to road sides

**Rockslide November 10, 2003 across Washington (U.S.A.) Highway 2 in the northern Cascade Mountains.

Preventative Measures for Rockfalls and Topples Heavy wire nets or fences

o So if anything does fall down it won’t fall on a road or a community Barricades along roadsides

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Shotcrete (cement mixture applied to restrict water access)

Rockbolts ***Barricade designed to stop rock topples and falls from steeply dipping limestone beds

near Sorento, Italy. ****Gabion barricade, made of wire cages filled with cobble and pebble, along a highway

near Frenchman’s Cove, Newfoundland and Labrador. *****Rockbolts and shotcrete stabilize a heavily fractured road cut, Acapulco, Mexico.Transitional SlidesTransitional Slides Slide: involves the movement of a slab of rock, debris, or cohesive mud as a single unit. Translation Slide: a landslide that moves along a regular sloping planar surface.

o Typically occurs where a block of material is underlain by a weak surface that is more or less parallel to the slope.

If you have a slope there is a slide that is on the same angle of the slopeo Planes between sedimentary bedso Old faults and fractureso Debris or cohesive mud over underlying bedrock

Block can travel down slope as:o A cohesive unit (e.g., The Vaiont Slide)

Just staying stuck together and go down as one piece o Or lose internal cohesion and break up as it travels downslope (figure to the left)

Or it may break apart *The 1983 debris slide at Thistle, southeast of Salt Lake City, Utah, was caused by rising

groundwater levels from heavy rainfall and melting of a deep snowpack. Vaiont Slide – Italy Massive translation slide on October 9, 1963 Southern alps of northeastern Italy 1960 construction of Vaiont Dam caused an increase in pore water pressure in the fractured

rocks above the newly created reservoiro Increased water table in surrounding area, mixed with lots of rain that was happening and

was very prone to failure – even before they built the dam – caused the entire slope face to move completely down into the reservoir which caused 120 meter wave to destroy many communities

Slide displaced all of the water in the downstream half of the reservoiro 125 metre high wave crashed over the damo Destroyed Longarone and four smaller villages downstream

Rotational Slides (Slumps)Rotational Slides Rotational Slide (Slumps): a landslide in which the mass rotates as it slides on a basal slip

surface.o As it moves down slope – all the weight at the top is the driving force and moves down

while rotatingo Areas along rivers are vulnerable to this as the moving water wears down the sides of bankso Can be prevented by adding weight to the bottom of the hill

Creep

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Creepo Creep: extremely slow downslope flow of sediment on the surface.o Gelifluction: downslope creep driven by sequential freezing and thawing.

Where the ground/soil slowly creeps down the hillo Not a hazard to human life but can cause a lot of economic damage o Mostly caused by freezing

Debris Flows, Grain Flows, & Mud FlowsDebris Flows, Grain Flows, and Mudflows Flows: slope failures involving material that has lost internal cohesion – material that isn’t

stuck together and moves down slope – deforms as it moves – different velocity and so ono Moves plasticallyo Deforms as it moveso Different sections of the flow move at different velocities

Flow Classification Mud Flow: a flow of mud, rock, and water dominated by clay-sized particles

o Very fine grain, can move very rapidly Grain Flow: a flow involving movement of broken rock, with little sand or mud, and particle-

particle contact; usually developed in gravel or sand.o Movement of broken rock

Debris Flow: a slurry of rock, sand, and water flowing downslope; water usually makes up less than half of the flow volumeo Landslide – slurry of sand rock and water that is moving down hill, water makes up less

than half of the flow volume Leda Clay in the St. Lawrence, Saguenay, and Ottawa Valleys Leda Clay

o Result in mudflowso Clay that was deposited when there was salty water involved

Quick Clay: water-saturated mud deposited in salty water composed of clay flakes with large pore spaces between the flakes; highly unstable.

*Lemieux Landslide, June 20, 1993. The community that had occupied this site had been relocated in good time prior to the failure of the Leda Clay slope.o Was a community that was in this region that moved in time for the flow to happen a few

years laterGrain Flow Large pieces of broken rock that flow down hillDebris Flow Move rapidly down slope; up to 100 km/hr Slippage at the base of the flow enhances the flow’s ability to scour & entrain more material Moves in surges

o Each surge has a steep front with course boulders When it stops it could be re-mobilized again

o Individual surges may slow or stop and then remobilize by another surge Bouldery natural levees formed along a major 1996 debris-flow channel, a tributary to the

Columbia River, near Dodson, Oregon. Large Boulder concentration at the top of the deposit. Largest materials are pushed to the front and sides

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o Largest materials pushed to the front and the sides When flow stops, natural bouldery levees often form Finer-grained material at the end of the flow takes longer to stop flowing because it takes

longer for water to drain out of the pore spaces.Reducing the Risk From Flows Installation of detection devices, such as acoustic flow monitors

o Only gives a couple of minutes of warning Often not enough time to evacuate people

o Not enough time to evacuate people downslope Prohibit building at the base of mountains and in dangerous areas along steep slopes Zone hazardous area as open space for parks, golf courses and agriculture

o Areas that are not high in human concentrations Construct walls to deflect debris flows

o Huge dams to resist movement Construct check dams to slow debris flows Construct debris basins large enough to channel and contain debrisSturzstroms (Rock Avalanches)Sturzstroms (Rock Avalanches) Sturzstroms: extremely rapid downslope movement of large volumes or rock and debris. Largest and most destructive landslides Typically begin as rock slides, but breaks up, entraining air & water

o Which can increase speed as it goes down hill Travel velocities as high as 100-300 km/hr Can travel distances up to 20 times their vertical fall

o Theories as to why they pick up size and speed Examples:

o 1903 Frank, Albertao 1965 Hope, British Columbia

Mechanism that causes sturzstroms to have such high velocities and long flow paths is still under debate

Sturzstrom may flow as a fluid composed of rock fragment suspended in air (fluidization)Frank, Alberta, 1903 Started as a translational slide; gained speed and developed into a sturzstom

o Started to take in air and water Moved on a pillow of compressed air which allowed it to move fast

o Apparently started by fractured lime surface Event lasted less than 100 seconds Slope failure occurred along fractured limestone planes Based on the speed and distance of the sturzstrom, it is thought to have traveled on a cushion

of compressed airHazard Mapping & Assessment GIS software can help identify areas of past and potential failures by mapping attributes that

contribute to slope failures. Going out into sites and looking at site attributes

o Slope Are they steep or gentle slopes?

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o Bedrock type (lithology)o Sediment texture and depth

Texture and depth, materials, cohesive materials?o Vegetation

Is there vegetation that can prevent water infiltration?o Drainage

Can water easily flow outwards and prevent slideso Concave upward curvature

Can this area result ion rotational slideso Historic slope failures

Looking at the history of slope slides in the region

LAND IN MOTION: SUBSIDENCE, COLLAPSE, AND KARSTOutline Introduction Karst Land Subsidence Thermokarst and Permafrost MeltingIntroduction Subsidence: relatively slow movement of land, typically at rates of cm/yr

o Land subsides down slowly Collapse: rapid movement of land, ranging from cm/hr to m/s of material disappearing almost

instantaneouslyo Material that just collapses downwards and moves very quickly

Karst Karst: topography resulting from dissolution of carbonate, gypsum, or evaporite rocks by

water.o Landscape formed by water that dissolved the rocks in the area

Characteristic terrain:o Doline: a circular or oval feature resulting from the dissolution of rock

Rock dissolved and land gone into the depressiono Sinkholes: a ground depression caused by collapse into an underground caverno Caverns: a large natural underground cave or tunnel

Dolines and Sinkholes Dolines form by:

o Surface solution: occurs where soil cover is thin and highly permeable. Water infiltrates the ground and wears underground down and soil on top

begins to go down and depresso Cover Subsidence (Suffusion Doline): occurs where a cap of permeable sediment

overlies soluble bedrock. Bit more sediment on top

o Collapse (Collapse Doline or Sinkhole): occurs where a layer of impermeable sediment overlies soluble rock.

Salt Deposits and Karst – dissolve very rapidly Halite: mineral or rock composed of sodium chloride; susceptible to dissolution

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o Deposits located in: Goderich and Windsor, Ontario Sylvite (potash): mineral composed of potassium chloride, a salt used in manufacturing

fertilizero Deposits located in: eastern Saskatchewan and near Sussex, New Brunswick

Gypsum, Limestone, & Dolomite These soluble rocks/minerals dissolve at much slower rates than halite and sylvite.

o Can form caverns underground Gypsum: mineral or rock composed of hydrated calcium sulphate. Limestone: mineral or rock composed of calcium carbonate. Dolomite: mineral or rock composed of calcium magnesium carbonateDissolving limestone – how does this work? Rain water and carbon dioxide creates an acid that dissolves the limestone creates a solution

and flows away with the watero Can create very large cave systems underground

Water pouring through fractured limestone drips down creating stalacites dripping down to form stalagmites

Climate and Karst Climate Factors: Rainfall Temperature Vegetation Soil TypeGuatemala 2010 Sinkhole caused by floodwaters from tropical storm Agatha 60 ft/ 20 m wide 30 stories deep! Both were in Karst environmentsLand SubsidenceSubsidence Subsidence: settling of the ground in response to:

o Extraction of groundwater Can also cause irreversible permanent reduction in aquifer porosity,

permeability & storage. Causing ground surface to go down

o Extraction of oilo Drying of peat

Very organic rich soil with very high water content and when you dry it out you decrease the volume of land

Subsidence in semi-arid Sacramento-San Joaquin Valley caused byo Groundwater pumping for crop irrigationo Decomposition of organic matter in the sediments from agricultural activities.o Land decreased by 8 meters from 1925-1977

Leaning Tower of Pisao Leans because of the weak land it is built on which is slowly going down and pushing

out the water in itThermokarst and Permafrost Melting

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Permafrost and Ice Permafrost: ground that remains frozen (below 0oC) for at least 2 consecutive years. Permafrost terrain divided into:

o Isolated (<10%)o Sporadic (10 - 30%)o Discontinuous (30 – 90%)o Continuous (>90%)

Interstitial Ice Interstitial Ice: ice that crystallizes in pores between grains of sediment.Segregated Ice Segregated Ice: lenses of pure ice developed in permafrost sediment

o Much larger volume of ice and cause top soil to collapseo Issue for communities built near areas of segregated ice

Thermokarst Thermokarst: karst-like landscape in permafrost terrain caused by melting of permafrost

under-increasing temperatures. Causes:

o Warming climateo Erosion along coastlines and rivers where ice-rich sediment is exposedo Fire heating the ground surfaceo Vegetation removal

Thermokarst Lakes Thermokarst Lakes: circular, oval or square lakes formed by thermokarst meltingTuktoyaktuk, Northwest Territories Community that is the most northerly point in Canada accessible by road Highest point is 25 metres above sea level Flooding and land loss caused by:

o Rising Sea Levelso Coastal Erosion (1 metre a year since 1980)o Thermokarst Activity

RIVERS AND FLOODING: FACTORS IN HAZARD AND RISKOutline Introduction Precipitation River Flow and Sediment Transport River Classification and Flooding Hydrographs Floods on Frozen or Water-Saturated Ground Flood Frequency and Recurrence IntervalsIntroductionFlooding Factors Intensity and Duration of Precipitation

o Greatly impacts the flooding that we haveo Heavy rainfall in short period of time can cause flooding

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o Rainfall for a long period of time too can cause flooding Sediment type and availability

o Clay like sediments just flow down to the nearest rivero Soil type sediments infiltrate the ground and take longer to get to the river

Land useo If rain hits a road or building they just run offo However soils and trees can capture the water

Engineering Modificationso Have we modified streams and rivers and create dams?

Canadao 10-20 Floods between 1974-2003

Certain events more intense and have caused more deaths then otherso Large increase in economic impact of floodings

A lot of people have renovated basements where flooding goes first and more is lost than 50 years ago

o Flooding occurs along the major rivers in the regionsPrecipitationFlooding from Precipitation High Intensity & Short Duration: Large amount of precipitation falling in a very short time

period; Flash Floodo Large amount of rainfall in a short period of time not giving the soil enough time to

take it all ino Can lead to flash floods

Which flood areas and can lead to many casualties Lower Intensity & Long Duration: Large amount precipitation falls steadily over a longer

time periodo Rainfall over a few weeks that is continuouso River volume starts to increase and increaseo Not as many casualties as flash floods but can cause a lot of economic activities

Watershed (Drainage Basin) Drainage Basin (Watershed): the upstream area from which surface water flows towards the

channel. Drainage Divide: topographic line or boundary separating watersheds.

o Topographic divide of a riverRiver Flow and Sediment TransportDischarge Discharge (m3/s): measured volume of water flowing past a cross section of a river in a given

amount of timeo Volume of water that moves past a point in a river and its speedo Can look at how high and deep the water is

Measuring stream velocities to estimate average stream velocity and stream dischargeStream Gradient & Floodplains

o Can measure different areas of a river Gradient: slope of the river channel; typically decreases downstream.

o Steepest slopes at the tope of the river and slowly go down as you go down the river

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Floodplain: relatively flat lowland that borders a river, usually dry but subject to flooding.o Area that is vulnerable to floodingo Usually the area around the river

Base level: an elevation that a stream cannot erode past, controlled by level of the body of water which the stream discharges into

o As soon as it reaches a body of water like a lake or ocean it will no longer be ablke to erode past that point

Alluvial Fan Alluvial Fan: a fan-shaped deposit of sand and gravel at the mouth of a mountain canyon,

where the stream gradient flattens at the main valley flooro Stream flows very quickly and makes its way to the base level and deposits the water

in a fan shapeDelta Delta: accumulation of sediment deposited by a river at its entrance into a basin

o River flows along at a good speed and hits water body that isn’t flowing anymore and water its carrying loses its suspension

Bankfull Channel: Width, Depth & Capacity Bankfull: when the water level in a river is equal to the height of the banks.

o **When the water reaches the bank it is a bankfull**o Flooding occurs when water rises above bankfull levelso Rivers do not reach bankfull stage every year.o Determining channel bankfull width and depth can approximate the bankfull

discharge and the capacity of the channel.Stream Equilibrium Graded River: a stream in equilibrium with its environment:

o Channel slope (grade) is adjusted to accommodate the amount of water and the amount of sediment and grain sizes provided to it

As a rivers flows over time and sediments are equal to its environment Dynamic Equilibrium: the condition of a system in which the inflow and outflow of material

is in balanceo As water flows it picks up and deposits material and this is when it becomes equal

Sediment Size Suspended Load: finer particles, such as clay, silt, and fine sand, carried in suspension

o Carried in the water and flows along Bedload: heavier sediment in a stream that is moved along the stream bed rather than in

suspensiono Instead of flowing along the water its rolls on the bottom

Objects of higher density takes more velocity to get the movingo More energy to get them going

*Rivers that carry silt and clay look very muddy and the water is not very clear at all **Rivers that carry gravel are very clear and you can see through them a lot moreNatural Levees Channel geometry is controlled by flow velocities and its associated sediment load carrying

capacityo When you decrease the velocity of water it can no longer carry what it had and it is

left behind and start settling creating natural levees

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o Creates a bigger channel and can prevent floodingsManning’s Equation**River Classification and FloodingMeandering Rivers Meandering River: river with a single channel and high to moderate sinuosity. Cutbanks (CB) form on the outside of meander bends where the water is accelerated along the

outside wall and erodes into the bank.o As the water gushes around the highest velocity goes on the outside and erodes into

the bank Point bars (PB) form as sediment is deposited in the slower water on the inside of the

meander bends. Thalweg: the deepest parts of the channel along the length of the stream bed

o The velocity of the water is fastest herePool and Riffles Pool – becomes the deepest part of the banks and is located where the cut banks are Riffles – the straighter parts of the riverOxbow Lakes A river that meanders around you have cut banks that erode and eventually separate from the

river These features can pose an economic risk

o Cant build a house near a cut bankBraided Rivers Braided River: a river characterized by multiple, frequently shifting channels.

o Common in regions where there is a strong seasonally and monthly variation in stream discharge

o During short periods of high discharge a braided river carries the coarsest sedimento Develop in regions where sediment is readily available

Bedrock Channels – rivers that are completely surrounded by solid rock The Bulkley River, near Moricetown, British Columbia flows in a bedrock confined channelGaining Stream Water from the water table moves towards the streamLosing Stream Water from the water table moves away from the stream When you have a large river that flows fast, water moves out and flows creating a water tableHydrographs Flood hydrographs nearest the rainfall area is highest and narrowest. Farther downstream, the

flood hydrograph crest is not as high but lasts for a longer duration. Looks at the time of an event and its discharge

o You can get peak in the amount of discharge in that rivero In areas where there is a lot of paved surfaces in reaches the rivers a lot more quickly

Higher stream discharges much more quickly How far you are from the storm area is also a factor

o If you are close the water reaches your area first and lot fastero Water can be dissipated in a large area

The farther you are away the lower your flood event in your area will beFloods on Frozen or Water-Saturated Ground

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Freshet Freshet: increased stream flow resulting from snowmelt and spring runoff.

o As you move from winter to spring all that snow melts goes into the nearest river and can create a massive flooding event

Rain-on-Snow Flooding Rain-on-snow flooding: a flood triggered when rain falls on snow cover and cannot infiltrate

into frozen soils.o Since snow blocks rain from getting into the ground it goes straight to the river

causing a flooding eventsDynamic and Thermal Ice Jams Dynamic Ice Jams: an ice jam resulting from the physical accumulation of ice at a

constrictiono Often occur as you move from winter to springo Ice moves down river and can get stuck and dam up a river creating a flood evento Surface is rough

Indicates it has gone through a lot of thrustingo Can produce gravel ribs

Thermal Ice Jams: an ice jam initiated by rapid change in temperature.Red River 1997 Flood: Manitoba, Canada and North Dakota, U.S.A. The Red River Floodway is designed to channel floodwaters around the city of Winnipeg.

When a flood is anticipated, water from the Red River is diverted around the city to the east, reducing water levels

Caused by ice jams Manitoba built the Red River floodway to prevent floods in the city of WinnipegExploits River 2003 Badger, Newfoundland and Labrador Flood Information Map for Badger. Inundation caused by a 20-year flood is shown in orange

and the area flooded during a 100 year flood is shown in yellow Caused by ice jams

o Ice moving down stream that eventually jammed up Were able to map out the area in the case of a flood Since it was winter the temperature dropped and the water in the flood began to freezeFlood Frequency and Recurrence IntervalsFlood Frequency and Recurrence Interval Recurrence Interval: the average time between floods of a certain discharge. Exceedence Probability: the probability that a certain discharge will be exceeded in a single

year (inverse of recurrence interval) 100-Year Flood: a flood with a recurrence interval of 100 years. 100-year Floodplain: the area likely to be flooded by a 100-year flood **This is all based on the information that they have avalible to themPalaeoflood features used to determine flood levels Looking at scars at trees to determine flood levels Looking at the soils in the region Help scientists determine what will happen in the next flood events

o When, Where, and What will happen

MIDTERM EXAMINATION

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Midterm: Tuesday, May 24th @ 7pm Writing Locations: Last Names:

o A – K MDCL 1102o L – Z MDCL 1110

Must bring your Student ID Must fill out scantron correctly – name, student number, and version number 1 hr midterm (from 7 - 8pm) Covers Lectures and Chapters 1-10 Format:

o 30 Multiple Choice Questions (30 marks)o 15 Definitions (15 marks)o 3 Diagrams (to label) (12 marks)

Test out of 57 marks total Test worth 25% of your final grade If you studied the lecture notes you should be fine on this test

o Be sure to go over the assigned readings

TROPICAL CYCLONES, HURRICANES, AND TYPHOONS Commonly called Hurricanes but are also called cyclones and typhoons

o Many different namesOutline Formation of Tropical Cyclones Tropical Cyclone Tracks Damage from Tropical Cyclones Deaths and Costs from Tropical Cyclones Response Hurricane Katrina: A case studyFormation of Tropical CyclonesFormation of Tropical Cyclones Hurricanes are large rotating cells The main development regions are between 5o and 27o north and south of the equator

o This is the area of deflections of winds when the Earth rotates and areas of warm ocean water

Necessary conditions for formation include:o Warm ocean water (>26.5oC) to a depth of 20 meters

Warm ocean water warms the air above, the warm air rises and cools and releases heat energy up above and starts off as a thunderstorm that accumulates and grows over time

o Convergence of air masses to form areas of low pressure Two air masses combining and pushing warm air upwards

o Coriolis effect Due to the Earth’s rotation

West to East Need rotation of wind to form a hurricane

Air is fluid and does not rotate as quickly as the earth and creates winds

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Things appear to deflect to the right in the northern hemisphere and left in the southern Hemisphere

o Low wind speeds aloft Low wind speeds in the upper atmosphere Low winds allow system to come together and form

Growth of a Tropical Cyclone Tropical Disturbance

o Thunderstorms developed in a zone of convergence can cluster Warm air rises, condenses, creates clouds and rains End up with a massive thunderstorm

o Condensation and release of latent heat continues to warm air Continues to warm the air

Tropical Depressiono Minimum wind speeds of 40 km/h

This is when you start to get the spiraling and rotationo Convective spiral and rotation develops as warm air spirals upwardo Decreasing pressure at the surface increases wind speed and subsequent evaporation

As the depression moves over the ocean waters it sucks in more warm air Tropical Storm

o Minimum wind speeds of 62 km/ho Eye forms as warm air from the high-pressure aloft is sucked down into the centre

Rotation forms an eye and the spiral pushes everything outwards The eye is generally calm due to downdrafts of air

Tropical Cycloneo Officially becomes a tropical cyclone when sustained wind speeds exceed 119km/h

Or aboveStructure of a Tropical Cyclone The eye – where air rises very rapidly releasing its heat Cyclone is rotating Clear skies during a hurricane within the eye Wind speed profile across a typical hurricane. Highest wind speeds surround eye wall. Anything within the northern hemisphere that experiences this force rotates counter clockwise

o Anything in the southern hemisphere rotates clockwise Wind speeds

o Highest speeds at the eye walls – and greatest precipitationo Within the eye there are low wind speeds

Tropical Cyclone TracksTracking Tropical Cyclones Track can be monitored by satellite. Thermal images measure storm intensity while Radar

images can be used to estimate precipitation amounts Hurricane tracks are predicted using weather forecast models, which use data such as ocean

temperature and location of other weather systems. Along the North Atlantic, hurricanes often follow the warm Gulf Stream

o Used to monitor to see where the hurricane will goDamage from Tropical Cyclones The Saffir-Simpson scale is used to categorize tropical cyclones on the basis of maximum

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sustained wind speed (over a minimum of one minute) and barometric pressureo How intense is the tropical storm?

Cyclone Damage: Wave Damage Storm surge – large waves eroding the sand on shorelines and beaches Hurricane Irene (1999) eroded much of the sand from a beach in Melbourne Beach Florida. Hurricane Dennis (1999) eroded much of the beach from under these beachfront homes in

Kitty Hawk, North Carolina. Hurricane Opal (1995) severely damaged a hotel in Panama City, Florida

o Waves underlined the structure causing it to fail Hurrican Bertha (1996) Cyclone Damage: Storm Surge Storm surges occur due to the low atmospheric pressure and the strength of the winds in the

tropical cyclone (set up). The height of the storm surge also depends on the tidal cycle. During Hurricane Juan at Halifax the height of the storm surge (red) was almost as large as the tidal range (green line). Had the storm coincided with the high tide inland flooding would have been worse

o Storm surge + high tide = damage and push inland, high water inlando Storm surge + low tide = little damage, low water inland and does not push inland

In the Northern Hemisphere the highest wind speeds and largest storm surges are observed in the North to Northeast quadrant of tropical cyclones. Here the direction of the winds are coupled with the movement of the storm.

Bangladesh is very vulnerable to storm surges from tropical cyclones. A high population density (150 million people) and a high rate of poverty contribute to the high death tolls that the country has faced over numerous cyclones.

o Hurricane shelters built to protect people Buildings on stilts

o Reduces the risk of heavy damage due to hurricanes Cyclone Damage: Wind Damage In the Northern Hemisphere the highest wind speeds and largest storm surges are observed in

the North to Northeast quadrant of tropical cyclones. Here the direction of the winds are coupled with the movement of the storm.

o Areas being hit with the wind directly blowing at it Can pick up items and throw them away

Wind does much of the damage to structures. Roofs often fail - particularly vulnerable are low sloping roofs with large overhangs. Larger roof spans are also more vulnerable (e.g. grocery stores). Flying debris greatly increases damage caused by wind

Wind damage and track of Hurricane Juan (category 2, September 29, 2003), which caused 8 deaths and $200 million dollars in damage over Nova Scotia

o Can reach as far north as Canada and cause heavy damages there tooCyclone Damage: Rainfall, Floods and Mudflows Hurricanes can lead to other disasters afterwards

o High death tolls and economic damage Hurricane Mitch dropped up to 1.9 metres of rainfall, killing over 9000 people. Most of the

deaths were due to floodwaters and mudflows A dissipating hurricane Hazel combined with a low pressure system to cause extensive

flooding in Toronto. 81 lives were lost and 1,895 families were left homeless. 225

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millimetres of rain dropped as the storm passed over Toronto. This caused extensive flooding along the Humber and Don rivers

o As it moved north and combined with another low pressure system and caused heavy damages

Deaths and Costs from Tropical Cyclones Deaths in tropical storms are related to factors beyond wind speed and surge height: Evacuation: In the figure opposite, people are attempting to evacuate during landfall of

Tropical Storm Francis (1999).o Can decrease the loss of lives

Disaster management: plans must be in place as communication, power and roads are damaged.

o Plans put in place such as communication and power can also save a lot of liveso If you plan ahead your chances for survival are much higher

Economic Capacity: 2/3 of deaths due to Atlantic hurricanes have occurred in developing countries of the Greater and Lesser Antilles of the Caribbean

o Richer countries can deal with natural disasters a lot betterResponseIf Trapped in a Hurricane: Stay away from glassed areas

o Easily blown out by win Listen to emergency information on battery powered radio

o Power lines can go down so have batteries If required, evacuate to designated shelter following evacuation routes

o Go to your designated shelter if ordered to Abandon mobile homes for shelter elsewhere If power is lost, unplug major appliances If outdoors, take cover avoiding bridges and overpasses

o Can often feel Abandon vehicles for stronger shelter

o Can be tossed and damagesHurricane Katrina: A case study Not just the hurricane that caused damage but also human impactsThe Setting: New Orleans Prior to Hurricane Katrina Due to subsidence much of New Orleans sits in a bowl up to 7 meters below sea level and

meters below Lake Pontchartrain and the Mississippi Rivero New Orleans is below sea level and were very vulnerableo Also built on spongy soils

The engineered levee and flood control system had been designed to handle hurricanes of a Category 3 strength.

o Only built to sustain hurricane category 3 windso The hurricane was a category 5 and the levees failed

Hurricane Katrina On course for New Orleans, Hurricane Katrina strengthened to a category 5 storm; however,

it made landfall on August 29th as a Category 3 storm.Planning and Evacuation The majority of people complied with evacuation orders although many residents,

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predominately in very poor neighborhoods, did not. Many of these people did not have transportation or the necessary finances

o Fair number of residences in the poor areas that had no transportation to help them evacuate

Few buses were sent for the estimated 100,000 people without access to transportation. The main evacuation centers (Superdome and Convention Center) did not have adequate

resources for the number of residents who took shelter thereo Were not prepared to deal with the amount of people that were coming and help did

not come for dayso Resources were scarce

Approach and Landfall Much of the damage was caused by the storm surge that raised the level of Lake

Pontchartrain and the canals that typically drain water from the city. Twelve major breaches to levees drowned portions of the city below 4 meters of water. The pumps that lift water out of the city failed.

o Only were meant to deal with rain water Large parts of the lower ninth ward were completely destroyed Flooding on Interstate 10Contamination, Disease and Mould Relief to survivors did not come quickly. People waited up to 4 days for food, water and

medical supplieso Anybody injured during the storm were unable to receive medical attention

Oil spills, trash, and human bodies combined to form highly contaminated water. Hospitals treated many patients with gastrointestinal problems and dehydration.

o Water was highly contaminated and a lot of diseases Mould rapidly grew in buildings that had been submerged.Death and Losses Confirmed deaths due to Hurricane Katrina totaled 1,383 39% of those who died were older than 75 years New Orleans faced considerable financial crises including loss of businesses, and loss of tax

base to pay teachers, police and other city employees. Less than ½ of residents had flood insurance

o No means to rebuild their homeso $500 billion in damages

VIDEO: HURRICANE KATRINA – “STORM THAT DROWNED A CITY” National Hurricane Center – Florida

o Was on the look out for hurricanes and saw that Katrina was coming July 2004 – one year before Katrina

o Hurricane Pam strikes New Orleans with 120 km windso Disaster simulation to prepare for a deadly Hurrican

Attended by 300 people from federal and state level Many people were skeptical

August 23, 2005 – six days before Katrina hitso Hurricane seasono Hurricanes take heat from oceans and is the driving force to hurricanes

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o At this point the hurricane is a tropical depression August 24, 2005 – 5 days before Katrina hits

o 2004 – one third of New Orleans evacuated for hurricane Pamo Katrina is building

Winds at 59 miles an houro Technological advances allow predictions to be much more accurateo High winds cause high tides

90% of deaths in hurricanes come from high tides August 25, 2005

o Hurricane becomes a category 1o Begins to hit Florida

Dies down because there is not enough warm water but plenty in the Gulf of Mexico

o New Orleans surrounded by two bodies of water Mississippi River being one of them Original part of the city was built on the high ground and rarely flooded As the city expanded the wet areas were drained

The drainage cause the city to sink in the ground even moreo City below sea level by several meters

o Two types of levees Earthen and concrete – steel reinforced Built by US Army Corps of Engineers Only built to withstand a Category 3 hurricane

o Levees destroyed wetlands Caused the land to sink down and wash away Wetland are depleted

Storm surges rise August 27, 2005

o Louisiana State University – researchers create disaster exercise Knew that a disaster would happen

o Warnings of impending dangerso Evacuation orders giveno Heavy winds

August 29, 2005o Katrina strikes lando Veered to the East of New Orleanso Clear that something has gone wrong with the leveeso 15 foot wave smashes through the levees

City begins to flood Poorest districts suffer the most

o Northeast of New Orleans – storm surge is 28 feeto Canals begin to overflow and water pours into the heart of New Orleans

City’s drain pumps cannot pump out the water Next day – 75% of New Orleans is flooded 60,000 houses and communities declared damaged beyond repair

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o Over 1000 people deado 100,000 people stayed behind for the category 5 hurricane

Was it avoidable? o Over topping of the levees was found in the 9th ward

West New Orleanso Why did the levees in the East fail?

Engineering investigation Theory that they were undermined Undermined by their own foundations

Hurricane Katrina was followed by Ritao So many came that researchers ran out of Roman letters and moved to Greek ones

Alpha, Beta… One hurricane had the power of a hundred thousand atomic bombs Global warming has been invoked to describe the rise in temperatures and more violent

hurricaneso Not everyone agrees

They say that hurricanes have nothing to do with global warming Scientists agree that they are getting worse No more money to save New Orleans and prepare it for the worse

o Even though worse is expected to come Radical solution

o Raise the ground and add more sediments 800,000 people homeless

STORMS: THUNDER, LIGHTNING, HAIL, TORNADOES, AND DUSTOutline Weather and Climate Atmospheric Pressure and Weather Mid-Latitude Cyclones Thunderstorms Tornadoes Dust StormsWeather and Climate Weather refers to the day-to-day changes in atmospheric conditions: temperature,

precipitation. Climate is the long-term statistical average of weather conditions. Assessed using at least 30-

years of data.Atmospheric Pressure and WeatherAdiabatic Cooling Adiabatic cooling occurs when rising air cools as it expands without change in heat content For dry air the cooling rate is 10oC for every 1000m.Adiabatic Lapse Rates The saturated adiabatic lapse rate is less than the dry adiabatic lapse rate due to the release of

latent heat during condensation.Convection Heating of the Earth’s surface leads to rapidly rising parcels of air (convection) with

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subsequent condensation and cloud formation. Precipitation was observed following both of these photographs

Winds and Pressure Gradients Isobars demonstrate the typical sea level pressure patterns observed in January.Jetstreams Generalized pattern of global circulation with the typical jetstream locations shown at 60o and

30o. Jet streams typically form over regions with the greatest contrast in temperature.Mid-Latitude CyclonesCold and Warm Fronts Cold Front – cold air rapidly displaces relatively warm air as it advances. Heavy precipitation

results along a narrow band. Warm Front – advancing warm air rises slowly over the adjacent cooler air mass. Associated

with widespread clouds with moderate, steady precipitation. Relationship between a low pressure system and weather fronts. Note counterclockwise

circulation (Northern Hemisphere)Cyclogenesis Low pressure centres can develop as warm air to the south moves more rapidly than cold dry

air to the northCyclogenesis: Open Wave In the open wave configuration the cold front moves more rapidly than the warm front and

begins to overtake it.Cyclogenesis: Occluded Stage Occluded Front. This occurs when the cold front overtakes the warm front (as is beginning to

occur in the region shown in purple above). The warm front has been cut off by the cold front. Once occluded, the system will lose energy and dissipate ending the mid-latitude cyclone event.

Atlantic Canada, strong nor’easters cause damage and ice shove due to damaging mid-latitude cyclones.

ThunderstormsGlobal Distribution of Lightning (Thunderstorms)Development of an Ordinary Cell Thunderstorm Hot air rises to the clouds and mixes with the cold air and a storm is createdSupercell Thunderstorms Supercell thunderstorms differ from the ordinary cells due to rotational motion of the upward-

moving air. They develop when wind directions near the surface are different from conditions higher in the troposphere.

Lightning Charge separation occurs as the smaller upward-moving particles tend to carry positive

charges while the larger downward-moving particles carry negative charges. Thus the top of the cloud carries a positive charge while the middle to bottom of the cloud carries a strong negative charge.

Lightning as a Hazard: Kills approximately 7 Canadians each year Precautions:

o Take cover in enclosed buildings and do touch anything plugged in (phones)

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o Do not shower or wash disheso Stay away from open fields or open watero Avoid tall treeso If trapped in the open, crouch down, resting on the balls of your feet away from

others.o Avoid metal objects (fences, golf clubs and farm machinery)o Stay in car with windows rolled up and do not touch any metal in car (including

steering wheel, radio or gear shift)Hail Hail causes more than $3 billion in annual damage. Hail is associated with intense

thunderstorm activity. Development of large hailstones (golf ball-size) requires strong updrafts as the hail embryo would need to be suspended for 10 minutes or more.

Geographical distribution of hail eventso In Canada, hail strikes out west and northwestern Canada

Microbursts Microbursts: formed by a rapidly descending mass of cold air from a thunderstorm. Major

threat to aircrafts as it results in wind shear, which reduces lift.TornadoesTornado Development Tornadoes can form when there is shear in wind directions. Shear creates a roll of horizontal

currents. These currents are dragged into a vertical rotation axis by updrafts to form a rotation cell.

Tornado Formation The tornadoes in these images are associated with slowly rotating wall clouds. In (a) the

tornado descends from the wall cloud while in (b) a tornado forms above the wall cloud.Tornado Development Favourable conditions for tornado development occurs when two fronts collide in a strong

low-pressure centre. This can be recognized as a hook echo or hook-shaped band of heavy rain on weather radar.

Tornado watches are issued when thunderstorms are capable of producing tornadoes. Tornado warnings are issued if a tornado is spotted or Doppler radar show signs of rotation.Surviving a Tornado Move to a tornado shelter, basement or interior room Protect your head using a helmet if available Highway overpasses are not safe locations. Wind speeds can be amplified. Cars provide only modest protectionGeographic Distribution of Tornadoes in Canada All along southern Canada especially in the prairie province area and southern OntarioDust StormsMechanisms for long range dust transportDust transport A dust devil is a local source of wind blown dust. Satellite image of long range transport of dust carried from Africa to the Canary Islands.Dust as a hazard Affects human health directly due to inhalation or indirectly (water supplies or food) Inhalation of large quantities can result in silicosis

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Reduces visibility Reduces incoming amounts of solar radiation Human activity and dust storms The frequency of dust storms in China can be related to agricultural activity. Increased land

use and subsequent degradation has lead to an increase in dust storms

WINTER HAZARDSOutline Snow Freezing Rain Avalanches Ice-Dammed Lakes Sea Ice and IcebergsSnow The shapes of snow flakes are controlled by supersaturation of water vapour and temperature.

o Rhyming Snow on the Ground A 2003 study based on coroners’ reports from three counties in the Detroit area showed that

the 36 people who died of sudden cardiac arrest while snow shoveling outnumbered the death toll from any other natural hazard in that area.

The American Academy of Orthopaedic Surgeons estimate that 70,000 back injuries per year can be attributed to snow shoveling in the United States

The Ontario Chiropractic Association estimates that 70% of back injuries are snow removal related (shoveling or snow blowers)

o People hurting their backs trying to deal with the snowValue of Snow Snow is an important water source for groundwater recharge Insulates soil reducing frost penetration Important component of the Earth’s radiation budget due to its high albedo

o Reflects much solar radiationBlizzards Blizzards are extreme winter storms officially defined in Canada as:

o Sustained wind speeds greater than 40 km/hr, visibility less than 1 km, and wind chills equivalent to -25oC

Wind chill – temperature we feel when we factor in wind “White Juan” of Feb. 2004, (bottom left) dropped 95 cm of snow over Halifax with wind

gusts in excess of 120 km/hr piling snow drifts up to 15 metres in heighto Huge hazardo Reduced visibility

The direct economic cost of a blizzard over Victoria and Vancouver (December 1996) was $250 million

o Blizzards can lead to economic lossesWind Chill Relationship between air temperature, wind speed and wind chill. Freezing to human skin

occurs almost instantly at -50oC. In Canada, 80 lives per year are lost due to hypothermia, and frostbite (more than to all geological hazards combined)

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o Makes it feel colder outsideo The colder it feels to our skin, we are more likely to suffer from frost biteo -55 degrees Celsius – skin can freeze in two minutes

Freezing Rain Freezing rain develops when precipitation falls through layers of the atmosphere with

different temperatures. If the particle falls through warm air near but not at the ground, partial melting and supercooling can occur. Such particles then freeze upon impact with surfaces at the ground

o Moves from cold air to warm air to cold air again and becomes freezing raino As they hit the ground they instantly freeze

Ice Storms (Verglas) When the conditions for freezing rain persist for over a period of hours to days, the events are

classified as ice storms or verglas. The 1998 verglas brings warm moist air from the gulf of Mexico north to Ontario and

Québec. Relative precipitation amounts are shown Freezing rain amounts over Eastern Canada during the 1998 verglas. 100mm fell over

Montréal and east of Kingston.o Eastern Canada’s most costly disaster

Avalanches Avalanche: rapid downslope movement of snow as flow

o Like a slope fall but with snow Avalanches kill approximately 200 people per year In Canada 10-15 people die due to avalanche activity

o Recreational activity during death Most avalanches in Canada are associated with recreational accidents. The typical Canadian avalanche victim is male, 20-29, involved in backcountry recreation. Largest avalanche – December 13, 1916 – 10,000 people killed

o Italian Austrian AlpsAvalanches Factors contributing to avalanche formation:

o Alternating times of freezing and thawing, which can build depth hoar Re-crystalized snow

o A minimum of 30 cm of snowo Slopes of 20 to 40 degrees

That’s when snow moves rapidly downhillo Sun exposure can promote partial meltingo Recent precipitationo Strong winds

Avalanches have three parts:o 1. Motion is initiated in the Start zone.o 2. The avalanche moves downslope forming a Track.o 3. As it loses momentum it spreads and slows in the Run-out zone.

Powder Avalanches Powder avalanches involve the movement of powdery or granular snow forming loose,

turbulent flows down slopes of 20 to 40 degrees. Powder avalanches move rapidly (60 to 200

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km/hr). Compressed air forms wind gusts capable of knocking down trees. A powder avalanche at Lake O’Hara, Yoho National Park, British Columbia is shown.

o Very powderyo Creates a turbulent flowo Very powerful and known to take down trees

Hard-Slab Avalanches Slab avalanches, which involves detachment of blocks of snow, are the most common. They

contain a greater volume of snow than powder avalanches and there is a high probability for burial. Often generated from cornices.

o Moves down slope as a giant slabo Very high amount of snow and can result in burialo Cornice – giant mounds of snow built up on a side with no support

Wet-Slab Avalanches Wet-slab avalanches develop due to partial melting of snow. Freezing and thawing at depth

can develop weak depth hoar layers allowing overlying snow to glide across the surface. They move relatively slowly (15-60 km/hr) but are responsible for many deaths

o Move slowo Known to glide downo Can still be lethal

Ice-Dammed Lakes Unglaciated valleys blocked by glacial ice impounds water. Water can rapidly break through

the ice dam leading to rapid flooding. In Peru, the town of Huaraz sits below a large ice dammed lake. Failure of this ice dam could cause flooding and potential loss of life

Sea Ice and Icebergs Icebergs can be a hazard for shipping (i.e. the sinking of the Titanic off the coast of New

Newfoundland) Build up of sea spray is problematic for shipping (bottom left) and residents at the shoreline

of Bonavista, Newfoundland. Icebergs are parts of glaciers that break off and float around the ocean

WILDLAND FIRESOutline Causes of Wildland Fires Wood as Fuel The Burning Process Fire Weather Fire Suppression Reducing Risk Erosion Following Wildland FiresCauses of Wildland Fires Human and lightning caused fires in Alberta, 1996-2005

o Some years more human caused and some lightningo Lightning fire only natural fire

All other are human man Causes of forest, shrubland and grassland fires in United States, 1917-66

o Mostly ‘incendiary’ – on purpose

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o Second = smokingo Third = Debris burning

Number of fires each year in Canada (a) and total area burned (b). There is no correlation between the total area and the number of fires, as a few individual large fires account for the most of the area.

o No relation with amount of fires and areas burnedWood as Fuel Trees and shrubs are largely (50-75%) composed of cellulose and hemicellulose. Both of

these tissues burn at relatively low temperatures.o Doesn’t require much heat to ignite them

Other major components of trees and shrubs are lignin and extractables.o Lignin gives wood its stiffness. – takes higher temperatures to burn them

Burns by glowing combustion rather than bursting into flame. Tree species high in lignin (e.g., oak) will not burn as readily (e.g., pine)

o Extractables include resins, fats, oils and terpenes. Extractables tend to flame suddenly when exposed to heat.

Smoke, soot, and the compounds produced by partial combustion of resins, terpenes and tars can aggregate respiratory systems

The Burning Process To keep a fire burning, three things are necessary: oxygen, heat and fuel

o Can’t have a fire without all of themThree Wildfire Phases: Preignition – getting fuels ready to be ignited Fuel achieves temperature and humidity favourable to ignition

o Needs right temperature and dry humidity Preheating

o Heat absorbing phase. Fuel loses water and other chemical compounds Pyrolysis

o Thermal degradation of chemicals (ie. low temperature extractables)o Products include volatile gases, mineral ash, tars, etc.

These processes produce the fuel gasses.Three Wildfire Phases: Combustion Combustion: Process of burning something Begins with ignition

o External reactions liberate heat and light. Ie. Lightning and human action. Ignition doesn’t always lead to wildfires.

o Sufficient fuel must be present. Ignition is not a single process but occurs repeatedly as wildfire moves.Three Wildfire Phases: Types of Combustion Flaming combustion

o Dominates early fire. Transition from heat-absorbing (preignition) to heat-releasing reactions (burning/ combustion)

o Initiated by ignition of volatile gases produced during the preignition phaseo Rapid high temperature conversion of fuel into heato Most efficient producing the least amount of smoke and large flames

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Smoldering combustiono Least efficient phase of combustiono Produces the most smokeo Lacks flames – associated with conditions where oxygen is limited

Glowing Combustiono Phase where only embers are visibleo Oxygen reaches the fuel surface and charcoal burns with a yellow glow and no visible

smokeo Phase ends when temperature of surrounding char drops to a point where pyrolysis

can no longer occurHeat Transfer Conduction: Transfer of heat directly from molecule to molecule

o Fire at the base of a tree it moved up the free through conduction Convection: transfer of heat by the movement of heated air. Hot gases are less dense and rise,

pulls in fresh air to sustain combustiono Hot gases less dense and rise and pull in fresh air and have a fire moved rapidly alongo Wind pushes a fire along and can start spot fires which are fires away from the main

fire and ahead Radiation: Transfer of heat by electromagnetic waves. It increases the surface temperature of

the fuelThree Wildfire Processes: Extinction Point at which combustion ceases There is no longer heat and fuel to sustain fireFire Weather Necessary weather conditions include:

o Low relative humidity o Strong winds o Lightning activity

Natural hazard to start up their fires **Fine fuel – little twigs and such that can start a fire Average values of the fire weather index. Higher values indicate regions where fires are more

likely to start.Slave Lake, Alberta The town of Slave Lake was devastated by fires on May 15, 2011 People thought it was under control but spread rapidly from the strong winds in the areaIntensity The spread of fire is controlled by the speed of wind. Fires burn up slopes more rapidly due to

convection carrying heat upward towards the unburnt forest. Fireline: the edge of the fire The fireline intensity is calculated by the number of kilowatts of energy per square metre

along the fireline and estimated by the height of flames Firefighters on the ground are effective for firelines of low intensity (<425 kilowatts, just

over 1 metre in height). Air tankers are used for fires of greater intensity but are ineffective once flame heights exceed 3 metres

Structure of a large-intensity forest fireTypes of Fires: Crown Fires

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Flaming is carried via tree canopies. Driven by strong winds and steep slopes.Types of Fires: Ground Fires – more manageable fires Creep along under ground surface Little flaming, more smolderingTypes of Fires: Surface Fires Move along surface Vary in intensity Burn slowly with smoldering, limited flamingFire Frequency Trees like Cork Oak (bottom) have adapted to fire. Their spongy bark does not burn. Fire frequency depends on climate and the type of vegetation. Trees like Jack pine (top) are well adapted to fire, as the heat of the fire opens their cones

liberating the seeds.o Needs fire to reproduceo Fire can be good for forest renewal

Fire SuppressionFire Suppression Methods A variety of approaches are used around the world:

o In North America air tankers are commonly used.o Back burns are set to burn back toward the main fire. o In burnouts a large area in front of the fire is burned to reduce fuel supply. Prior to

setting the fire the area to be burned is drenched to reduce the potential of an uncontrollable fire.

Total Fire Suppression Total fire suppression in this pine forest of Idre central Sweden has resulted in a change to

forest ecology. Most notable is the absence of seedling trees. Two years after the large fires affecting Yellowstone National Park in the U.S. (1988) forest

renewal was underway.Prescribed Burns and the “Let it Burn” Strategy Strategies of total fire suppression dominated policy from the late 1940’s to the early 1980’s. Increased knowledge in forest ecology demonstrated the importance of fire for forest renewal

o Controlled for ecological reasons Total suppression resulted in large fuel accumulations resulting in larger fires Policy has shifted toward prescribed burns in some areas to reduce large fuel accumulations Natural lightning-caused fires were allowed to burn unless they posed threats to people,

commercial timber-lands or scenic attractions.Reducing Risk There is a growing number of interface communities bringing humans closer to fire risk Homes should be constructed with flame resistant material. Area around homes should be clear of brush. A clear emergency plan and response should be in placeErosion Following Wildland FiresErosion Soils not protected by vegetation are also more prone to gully formation, flash flooding and

debris flow

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In intense fires, organic material forms hydrocarbon residues which soak into the soil. These soils can become hydrophobic, impervious to infiltration

CLIMATE AND CHANGE: PAST, PRESENT AND FUTUREOutline Climate and Weather Climate Change: Natural Factors Measuring Past Climate Changes Recent Climate ChangeClimate and WeatherWeather and Climate Weather refers to the hourly, daily or weekly phenomena while Climate is the long-term

average.o Weather = particular dayo Climate = long term average

Various aspects of climate include:o Mean daily temperatureo Mean diurnal temperature variation

Maximum and minimum and the differenceo Mean annual precipitationo Seasonal distribution of precipitationo Mean amount of snowo Direction, persistence and strength of prevailing windso Other data of interest (i.e. average annual hours of freezing rain, average annual

number of thunderstorms)Climate Change and Climate Variation Climate change involves a shift in long-term conditions.

o Increase or decrease in value Climate variation involves deviations from a constant mean value (random or cyclic

variation) but does not necessarily involve a change in climate over a 30-year or longer time period.

Insolation Insolation: incoming solar radiation depends on:

o Distance to sun: closer to sun = more radiation Perihelion, January 3, 146,000,000 km

When the Earth is closest to the sun Aphelion, July 4, 152,000,000 km

Earth farthest away from the suno Composition of the atmosphere

50-60% of the sun’s radiation makes it to earth and is absorbed by the earth’s surfaceo The rest is absorbed along the way or scattered

Albedo is a measure of how much insolation is directly reflected. White surfaces such as a glacier have very high albedo values.

The Greenhouse Effect

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Thermal radiation and absorption of this radiation by greenhouse gases (carbon dioxide, methane, nitrous oxide and water vapour) is responsible for warming in the lower atmosphere.

o Gases that are really good at trapping radiation = greenhouse gases Mars (top) and Venus (bottom) represent extremes in the functioning of the greenhouse

effect. Mars has a very thin atmosphere so most thermal radiation escapes. Venus, has a thick atmosphere with high concentrations of greenhouse gases and has surface temperatures much warmer than on Earth (460oC).

o Mars = cold because of low concentrations of greenhouse gaseso Venus = high concentration of greenhouse gases and hotter

Atmospheric Composition Nitrogen – 78.08% of Earth Oxygen – 20.95% of Earth Argon – third largest in the Earth’s compositionClimate Change: Natural FactorsVariations in Insolation Insolation at the Earths surface varies slightly with sun spot cycles, although, sunspot activity

alone cannot explain differences in climate. Insolation has also varied over the past 4.6 billion years as the sun has aged.

o Sunspots – areas of the sun where little to no radiation reaches the earthAstronomical Factors Changes in seasons observed throughout the year are due to the Earth’s axial tilt (23.5

degrees) which impacts solar angle.o Earth is on a 23.5 degree axiso When the earth points towards the sun that is when we get our summer

Astronomical Factors: Precession of the Equinoxes Changes to long-term climate involve changes in the precession of the equinoxes over cycles

of 19,000, 22,000, and 24,000 years. Equinox – when the radiation is perpendicular to the equator

o Happens twice a yearo Changes over time

Astronomical Factors: Changes to Axial Tilt Changes to long-term climate involve changes to axial tilt over a 41,000 year cycle. Earth’s tilt moves over time

o 23.1 – 23.5 degreeso Can influence climate over timeo Slowly moves from one angle to the next

Astronomical Factors: Changes to Eccentricity Changes to long-term climate also involve changes in the shape of the Earth’s orbit that varies

in three cycles of 95,000, 125,000 and 400,000 years.o Does not necessarily rotate in a circle

Does have an elliptical rotation Constant warming and cooling of the earth

NOT ALWAYS HUMAN INDUCED**Earth and Atmospheric Factors Other variations in the Earth’s climate are related to:

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o Alignment of Earth’s continentso Changes to surface albedo

More glaciers = more albedo (reflection) which causes more cooling of the earth

o Changes to atmospheric compositionMeasuring Past Climate ChangesHistorical Records Historical records of grape harvests (Europe), rice harvests (Japan) and River flow (Nile)

provide excellent measures of historical climate change and variationo Would not have exact temperatures but could give us an image of the climate and

temperatures of an area over timeo Can look at river volumes and flow

Like the Nile floodingProxy Data Proxy Data

o Biological and physical signatures that result from climate conditions that can be used as proxies for past climate

To use proxy data the following must be established:o Thoroughly understand how the proxy works;o Understand how the proxy relates to a specific aspect of climate;o Know how the location relates to broader regional conditions;o Must be able to accurately and precisely date the events.

Biological Proxy Data We can infer climate conditions from fossilized animal remains. Wear on a mammoth tooth indicates that the animal grazed under prairie grassland rather than

a forest climate.o Can tell what vegetation they grazed on and therefore can tell what the climate was

that was suitable for this vegetation Prairie dog tunnels in central Alberta dug 22,00 and 33,000 years ago show a climate suitable

for prairie dogs prior to the last glaciation. We can infer climate conditions from fossilized plant remains Stump of a black spruce that was killed over 1600 years ago tells us what the climate was like

at Avondale Newfoundland around this time period. Exposed peat in Prince Edward Island contains pollen, which represents the vegetation

present over the past 2000 years. Figure 15-26, p. 398. Palynology Coring for palynological analysis on the frozen surface of Lake O’Hara, Yoho National Park.

Subsequent analysis of the assemblages of pollen and spores preserved in the sediment give useful records of past climate if the sediments can be dated. The photo on the right is a microphotograph of maple pollen.

Dendrochronology Dendrochronology is the analysis of annual tree rings and their variation. A tree’s annual

growth is recorded in growth rings (left photo). Annual tree growth responds to variations in temperature and water availability. The Bristlecone pine tree in Bryce Canyon National Park is relatively young at 2,000 years old.

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Analysis of annual tree rings can also be use to give evidence of past forest fire activity (left photo) or flood events (right photo).

o Fire – shows that the area was dry and gives indication of thato Flood – gives indication that the area was wet and had wet conditions

Landforms and Soils as Climate Proxies Advances and retreats of the Athabasca Glacier can be traced from moraine deposits.

o Retreating in acceleration since 1885 Crescent-shaped sand dune in Manitoba was a slowly moving sand dune approximately 6000

years ago. Now vegetation covers the dune.o Indicates that there was sand dune conditions in this area

Ice wedge cast found near Edmonton, Alberta, formed when the climate was similar to Inuvik, NWT.

Two palaeosols (B and A) are preserved under a sequence of sand dunes near the Oka River, south of Moscow, Russia. After an initial cold period, when dune sand was deposited palaeosol “B” formed approximately 13,000 years ago. Another cold period was followed by the formation of palaeosol “A”, approximately 11,000 years ago. The modern soil (at top) has formed over the past 2,000 years.

o Indicates different conditions over timeRecent Climate ChangeChanges to the Atmospheric Concentrations of Greenhouse Gases Have increased in the past 200 years or so Only reasonable explanation that people come to is industrial activity and human activityGlobal Temperature Change Changes in global temperature from the years 1000 to 2000 determined from proxy data

sources (blue) and thermometer readings (red).o Temperature is risingo Can be linked to human impact on the world

Future Climate Change Estimates of future global temperature change based on the results of several independent

climate models. The orange line indicates future temperature changes if the carbon dioxide concentration were stabilized at the year 2000 levels. The remaining lines indicate several different carbon dioxide emission scenarios bounded by the model uncertainties.

o If nothing is changed there will be significant global warming

CLIMATE VARIATION AND DROUGHTOutline Climate Oscillations Drought Sequential Stages of Drought and Their Impacts Impacts on People, Communities and SocietiesClimate OscillationsEl Nino – Southern Oscillation Wind and ocean temperatures shown during (a) normal and (b) El Nino conditions

o Variation in wind patterns and ocean currents in the Pacific Ocean and South Americao Normal conditions – dry conditions in South America and wet conditions in Indonesia

and Australia

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o El Nino conditions – Warm air rises in South America, wet conditions in South America while dry conditions and drought in Indonesia and Australia

o La Nina – amplifying normal conditions Wind and Ocean current patterns in South America

o Normal – cold water from Antarctica comes to South Americao El Nino – changes in air temperature and does not pull up cold water from Antarctica

and does not bring up nutrientsEl Nino Conditions Impact of El Nino on sea surface temperatures of the Pacific Ocean.ENSO Conditions Sea surface temperature anomalies in the mid-Pacific Ocean for 1900-2003. El Nino has

warm temperature anomalies.o Has huge impacts on certain areas

Global El Nino Impacts Global impacts of El Nino on temperature and precipitation.

o Affects global wind patterns and areas all over the globe Winter storms attributable to El Nino conditions result in the erosion of the parking lot due to

storm surges.o Stronger winter storms can lead to erosions

Effects of El Nino on rainfall patterns in Eastern Africa.o Can lead to dryer than normal conditions

Global La Nina Impacts Global impacts of La Nina on temperature and precipitation.

o Wetter conditions in Australia and Indonesia, cooler in North Americao Affects the entire world

North Atlantic Oscillation The North Atlantic Oscillation (NAO) is a cyclic variation in pressure regimes influencing

northern Atlantic environment and communities. NAO phases are defined by pressure differentials between the Icelandic Low and the Azores

High. When these are at maximum the NAO is in “positive” phase. Negative phase – difference not as greatNorth Atlantic Oscillation: Phases and Impacts Strongly positive NAO phases results in colder temperatures in Labrador and along the

eastern coastline of Newfoundland.o Colder temperatures and more precipitation in Eastern Canada and less in Northern

Europe and the opposite in a negative phase Positive and negative phases of the NAO index 1864-2001.DroughtDrought Severe natural hazard in many areas of the world often accompanied by famine and

starvation. Often called a ‘creeping’ phenomena because its arrival is not recognized until conditions

have deteriorated. Costs are more difficult to assess than other hazards, however, the 2001-02 drought has been

called Canada’s most costly disaster.o Worst drought in Canadian history

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o Affected BC, Prairies, Ontario, Quebec and Nova ScotiaImpacts of Drought Africa has had the most droughts

o 245 droughts between 1900-2007o Killed over 800,000 people and affected over 250 million people and caused 7,000

million in damagesSequential Stages of Drought and Their ImpactsMeteorological Drought Defining meteorological drought is regionally specific. A common tool is the Standard

Precipitation Index (SPI), which compares precipitation at a site to historical records as accumulated over a period of time (usually several months).

o Depends on the region and the average conditions of the region too SPI values for 9 months prior to February 2007. Sites with SPI values lower than -1.6 are

experiencing dry conditions while drought is occurring in regions less than -2. Meteorological drought conditions for September 2001- August 2002 (a). Areas in red are

record dry conditions. Contrast with conditions observed September 2005 – August 2006 (b).Agricultural Drought Agricultural drought considers the impacts water supply on plant growth. Dry periods during

a summer may not impact plant growth if water is available in the soil. o A few weeks of a dry period is not going to destroy your cropso Long periods of dry periods will destroy your crops

A commonly used index for estimating water available for plants (soil-water budget) is the Palmer Drought Index that compares estimates of the soil-water budget to average conditions.

Palmer Drought Index for August 2006. Soil water deficiencies are apparent in Northern Alberta and North Eastern British Columbia.

Hydrological Drought Hydrological drought is indicated by dropping water levels in reservoirs, rivers and lakes.

Meteorological droughts do not often immediately impact water levels in lakes and streams. Hydrological drought is more closely tied to human activities due to the demands that humans

place on water supply.Impacts on People, Communities and SocietiesDroughts in North America Impacts of droughts in North America: constant pulling out of water can cause the land to

subsideo Abandonment of farmland, southeastern Montana, USA.o Clouds of eroded soil produced by wind and drought conditions in Kansas and

Oklahoma.Droughts in Australia Drought is a recurring fact of life in Australia, closely tied to ENSO.

o 3 of 10 years are productive Australian wheat production is related to ENSO. El Nino years (positive ENSO values)

correspond to reduced wheat yields. Winter-spring rainfall for El Nino years as compared to average rainfall conditions. Droughts in Africa Droughts, very common in the Sahel regions of Africa, contribute to famine and starvation. Human actions have resulted in desertification that further enhances drought impacts.

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o Taking water from the ground dries out the lando Over grazing of the land too will dry out the land

Hydrological drought has lead to the progressive shrinkage of Lake Chad 1963 – 2001.o Decreasing rapidly

NATURAL ENVIRONMENTAL MEDICAL HAZARDSOutline Diseases with Natural Environmental Causes

o Yellow Fevero Malariao West Nile Viruso Sin Nombre Hantavirus

Medical Geological Hazardso Arsenic in Groundwatero Fluoride in Natural Waterso Radono Iodine

Diseases with Natural Environmental Causes: Yellow Fever Incubation period of 3-6 days. First phase of symptoms: fever, muscle pain, backache, headache, & vomiting 85% of victims recover after the first phase Other unfortunate victims develop the “toxic” phase with jaundice, internal bleeding and

kidney failureo Yellowing of the skin

50% of victims who develop the “toxic” phase recover Those victims who do not recover and left untreated die after 10-14 days. Aedes aegypti, the mosquito vector that transmits yellow fever to humans.

o Spread by mosquitoes Yellow Fever: Epidemics Yellow fever is native to West Africa

o Tropical climates favorable to yellow fever Areas with tropical and subtropical climates are more vulnerable then temperate climates. Failure to recognize the spread of disease was from mosquitoes, so efforts were concentrated

on quarantining victims and sanitation Spread to the Americas during European exploration Epidemic in Philadelphia, U.S.A., during the summer of 1793 killing 4,044 people Haiti 1801 epidemic killed 90% of Napoleon’s force that were sent to Haiti to crush a revolt

against the French colonial authorities Many large nineteenth-century homes in New Orleans had open verandahs and porches, with

many windows and doors, designed to encourage air circulation. Unfortunately, this also provided routes for mosquitoes to enter the homes

Yellow Fever: Today Yellow fever was eradicated from North America by the mid-1900s through a combination of

vaccinations, drainage of swamplands, and insecticide control of mosquitoeso Vaccinations – medicine to kill disease

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o Drains swampy areas where they breed Yellow fever is still present in 9 South American countries, and some Caribbean islands. 33 African countries suffer from Yellow fever epidemics. Countries reporting yellow fever epidemics to the World Health Organization of the United

Nations 1980-2003. Since this map was prepared, additional epidemics have been reported in western African countries and Sudan.

Malaria Kills between 1 to 3 million people annually

o Sub-saharan Africa suffers the most as well as South East Asia Malaria is spread by several species of mosquitoes. Malaria is caused by the four species of the protozoan Plasmodium which lives as a parasite

in the gut of a female mosquito The plasmodium transferred from mosquito to human will then reproduce in the human’s

liver and bloodstream causing malaria to develop. An infected person bitten by another mosquito can pass the mature Plasmodium on, thus

creating a transmission cycle Symptoms: high fevers, shaking chills, flu-like symptoms, back pain After infected another mosquito could bite you get the disease and spread it to the next person Eradication of every mosquito from the bayous of Louisiana would be impossible and

ecologically undesirable. A combination of control measures, including insecticides, and anti-malaria drugs, however, successfully eradicated malaria from Louisiana by 1951

o Attempts at eradicated malaria in North AmericaAreas Affected by Malaria Sub-Saharan Africa and South East Asia as well as South America

o Less economically developed areaso Sub-Saharan Africa – very wet areas and lots of precipitation

Great breeding ground for mosquitoes Global distribution of the different species of Anopheles mosquitoes. All of the areas shown

could be susceptible to malaria in the absence of either medical intervention or mosquito-control measures. Isolated malaria cases were reported in southern Ontario, Quebec, and Maritime Canada until the mid-1900s

Areas that receive abundant rainfall throughout the year have suitable breeding conditions for mosquitoes year-round. Breeding of malaria-carrying mosquitoes is only possible in desert regions if artificial sources of standing water, including irrigation ponds, are present

Distribution of the population at risk from malaria in Africa, measured as people per square kilometre. Increasing urbanization and displacement of refugees into relief camps increases the population at risk

West Nile Virus Originated in the area from Egypt to Iran

o West of the Nile River First detected in the United States in 1999

o Spread from mosquitoes to humans and or animals, especially birds Virus can cause encephalitis or meningitis

o Swelling of the brain and spinal tissueso Swelling of the membrane

< 1% of infected people will become seriously ill

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The spread of the West Nile virus through the U.S.A., 1999-2002o East Coast of the US – found in dead birdso Spread to humans as it moved further west

Human cases of West Nile virus reported in Canada in 2006o Manitoba the worst for West Nile

Has a lot of swampy wetlands perfect for mosquito breeding Relationship between West Nile virus cases in Denver, Colorado, with temperature and

precipitation, April 1, 2003 – November 25, 2003o Not linked to precipitation but linked to temperature

Sin Nombre Hantavirus A virulent hantavirus that kills approximately 45% of infected people

o Spread by deer miceo Can kill people by coming into contact with deer mouse droppings and saliva

May 1993 in New Mexico there were five inexplicable deaths of healthy young adults from respiratory failure; identified by the Center for Disease Control in Atlanta as a new variant of the hantavirus.

Victims contracted the virus by coming in contact with deer mouse droppings and saliva. Deer Mouse (Peromyscus maniculatus), the primary vector of the Sin Nombre hantavirus Wetter and warmer winters under El Niño conditions favour the growth of vegetation in

northern New Mexico. This allows rodent populations to expando Higher population of deer mice in these conditions

Chile also has this issue when their temperature is highMedical Geological HazardsInorganic Poisons Background Level: the level of the concentration of a substance under natural conditions. Some elements are naturally found in harmful concentrations in soils, rocks, and water; e.g.,

arsenic, fluoride, and radon. Other toxic element such as, mercury, lead, and cadmium, are harmful to humans when they

are used in manufacturing and productsArsenic in Groundwater High concentration of arsenic are poisonous and lower concentrations can cause skin cancer

and melanosiso Poisonous to humans

Arsenic occurs in more than 200 different minerals that are relatively rare and usually in low concentrations.

Arsenic dissolves very readily in groundwater and can move long distances from its source. When many sources combine, arsenic can concentrate in toxic levels in the groundwater. Concentrations of arsenic in groundwater from wells in Bangladesh. Concentrations above

50 μg per litre (red dots) are harmful to human health. The bar graph shows the percentages of water wells in each category; approximately 25% of the wells exceed the recommended maximum safe concentration.

Nova Scotia also has a high concentration in ground waterFluoride in Natural Waters Fluoride concentration greater than 1.5 milligrams per litre can become potentially harmful Exposure to high concentrations of fluoride can cause dental fluorosis and skeletal fluorosis

o Dental fluorosis – causes teeth to be disgusting and gross

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o Skeletal – breaks down the bones Fluoride is found in the common mineral fluorite and in certain types of micas and clay

minerals. Highest concentrations of fluoride are found in regions of volcanic activity, which produces

hydrofluoric acido High concentrations in volcanic areas

Unlike arsenic ions, the highly reactive fluoride ions in the groundwater tend to form chemical compounds within short distances of it source, therefore, high levels of fluoride are typically found close to its source material

o Does not travel very far Fluorosis is widespread in India, primarily as the result of drinking water or eating food with

anomalously high fluoride concentrations. Areas underlain by granites have the highest rates of fluorosis.

Radon Radon: a colourless and odourless noble gas.

o Produced by the radioactive decay of uranium, in particular Uranium-238 with a half life of 4.5 billion years, and other radioactive minerals.

o Radon decays to radioactive isotopes Polonium-218 and Polonium-214 which also produces alpha particles that if breathed or swallowed can cause several types of cancer.

o Uranium is found in several types of minerals associated with granites, metamorphic gneiss, and sedimentary rocks derived from weathering and erosion of granites.

o Radon can build up in the basement of a home constructed on soils with high radon levels or if the basement walls are built of granite

Nova Scotia – high radon concentrations Radium Hot Springs – pool where it was thought that it was good for you Can be prevented in homes by creating radon barriers in basementsIodine Iodine deficiency disorder occurs when humans are deprived of sufficient iodine levels. It

causes enlargement of the thyroid gland and children deprived of iodine from birth suffer from stunted growth and brain damage

Iodine in soils and groundwater originates from sea spray The global distribution of IDD indicates that the distance from the ocean coast is a critical

factor. The absence of IDD in Western Europe, Russia, and North America reflects the addition of iodine to table salt and consumption of dairy products

EXTRATERRESTRIAL HAZARDSOutline Solar Radiation Fluxes Projectiles from Space

o Asteroidso Meteors and Meteoriteso Comets

Previous Impacts with Eartho Astroblemeso Comet Impacts

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Chances and Consequences of an ImpactSolar Radiation Fluxes Electromagnetic radiation: radiation that moves with the speed of light. Plasma Streams: a stream of charged particles emanating from the sun. Charged Particles: hydrogen gas molecules emitted by the sun, which carry energy toward

Earth. Solar wind: stream of energized charged particles (a plasma) produced by the sun. Sun periodically ejects masses of material from its corona, producing solar prominences.

Sunspots also represent areas of activity on the surface. The solar wind (white lines) emanates from the solar flares and prominences, and from

plasma streams (shown diagrammatically as white plumes). The solar wind influences the configuration of Earth’s magnetic field (blue lines), as well as creating concentrations of charge particles 25,000 to 40,000 metres above Earth’s surface (brown), and in the ionosphere 1,000 kilometres above Earth’s surface (purple).

o Can create aurora borealis Potential disruptions from space weather can result from both charged (“solar flare protons”)

and ionospheric currents. Effects include disruptions to satellites, GPS, communication systems, pipelines, and power lines.

Micro-thin panels of ultra-pure materials, including silicon, diamond, silicon carbide, and gold, were exposed to solar wind during the Genesis mission. The particles of solar wind adhered to the panels, which could be analyzed after Genesis returned to Earth.

o Helped us understand what it is composed of Because we rely so much on technology this can interrupt our communications systemsProjectiles from Space: AsteroidsAsteroids: a small solid rock body orbiting the sun in the same way that Earth orbits the sun. Near-Earth Asteroids: an asteroid that passes through Earth’s orbit around the sun Type of asteroids based on chemical composition:

o C-type: magnesium-iron rich mineralso S-type: nickle and iron

Some magnesiumo M-type: pure nickle-iron

Asteroid 253 Mathide, 59 x 47 kilometres, was investigated by NASA’s NEAR mission in June 1997

The composite image shows two asteroids: Ida and Gaspra, and the two small moons of Mars: Deimos and Phobos, approximately to scale. Ida, the largest body of the four is approximately 35 kilometres along its longest dimension.

Meteors and Meteorites Meteors: a large extraterrestrial body that heats to a white hot incandescence when it streaks

through Earth’s atmosphere. Meteorites: an extraterrestrial fragment that survives passage through the atmosphere to

reach Earth’s surfaceo Called a meteorite when it lands on Earth

Type of meteorites based on chemical composition:o Chondrites: olivine and pyroxeneo Achondrites: similar to basalto Iron Meteorites: nickle-iron alloy

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o Stony-Iron Meterorites: magnesium, iron-rich silicates, in nickle-iron matrixComets Comets: a mass of ice, frozen methane, and some rock material traveling at a high velocity in

the gravitational field of the sun, but traveling outside our solar system before passing through it on occasion.

Bolide: a general term for extraterrestrial objects, including both asteroids and comets. Oort cloud: area extending more than 15 trillion kilometres beyond the sun, containing many

comets.Previous Impacts with Earth: Astroblemes Astroblemes: a crater of impact structure on Earth, formed by the impact of an extraterrestrial

objecto It’s a crater

Tektites: droplets of molten rock (glass) that may have formed by superheated splash from a hypervelocity impact of a meteorite on either the moon or Earth.

Shatter Cones: deformed conical structure formed by meteorite impact. The evolution of a moderate-size astrobleme:

o (a)A transient crater is excavated, compressed, and fractured, and the base of the cavity melts with the rim raised.

o (b)The ejecta blanket spreads around the cavity, and the rim slumps back into the cavity.

o (c)Fallback material partly fills the cavity, along with some melt-rich material. The evolution of a large astrobleme:

o (a)A transient crater is excavated, compressed, and fractured, and the base of the cavity melts

o (b)The base of the transient cavity rebounds as excavation continueso (c)The raised rim of the transient crater and central uplift both collapse to form a

larger and shallower crater basin partly filled with inward-facing scarps, large blocks, smaller fragments, and melt rocks

o (d)The final crater is much broader and shallower than the initial transient crater.Comet Impacts Tunguska event: a powerful explosion event that occurred over Tunguska, Russia. Believed

to have been caused by a comet or meteorite the exploded between 6 to 10km above the surface of the Earth. The shockwave destroyed the trees.

o Light flashes all across Europeo Took years before researchers could get ino Thought it was a comet or meteorite but nothing was foundo Theories arise – such as UFO’s

Biggest theory is that a meteorite exploded above the Earth and knocked down a bunch of trees

o Remote area – no one was killedChances and Consequences of an ImpactChances of a Large Asteroid Impact Near-Earth Asteroids (NEA): asteroid that passes through Earth’s orbit around the sun. Near-Earth Objects (NEO): an asteroid, comet, meteor, or meteorite that passes through

Earth’s orbit around the sun. Torino Scale: scale that measures the risk posed by near-Earth objects.

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The Torino scale, developed by NASA as a result of a scientific conference held in Torino, Italy, indicates the likelihood of the impact of a NEO with Earth and its consequences

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earth science 2gg3 - natural disasters (mcmaster university)

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