powerpoint presentation - tsunamis

TsunamisTsunamis

BANDA ACEH, INDONESIA: June 23, 2004 BANDA ACEH, INDONESIA: June 23, 2004 A satellite image of the waterfront area of A satellite image of the waterfront area of

Aceh province's capital city before the Aceh province's capital city before the tsunami.tsunami.

BANDA ACEH, INDONESIA: December 28, BANDA ACEH, INDONESIA: December 28, 2004 2004

An image taken after the tsunami shows An image taken after the tsunami shows destroyed housing and the shoreline nearly destroyed housing and the shoreline nearly

wiped out.wiped out.

What is a Tsunami?What is a Tsunami? When mass movement, such as an When mass movement, such as an

earthquake or landslide, suddenly earthquake or landslide, suddenly displaces a large amount of water from its displaces a large amount of water from its equilibrium state a disastrous wave called equilibrium state a disastrous wave called a a tsunamitsunami can form. can form.

Tsunami literally translates from Japanese Tsunami literally translates from Japanese to “harbor wave” but are often call tidal to “harbor wave” but are often call tidal waves because small, distant-source waves because small, distant-source tsunamis resemble tidal surges.tsunamis resemble tidal surges.

Tsunami SourcesTsunami Sources Earthquakes Earthquakes ((e.g.e.g. Sumatra, 2004: >200,000 Sumatra, 2004: >200,000

people killed; Papa New Guinea, 1998: ~3,000 people killed; Papa New Guinea, 1998: ~3,000 people killed)people killed)

Volcanic eruptionsVolcanic eruptions ( (e.g.e.g. Krakatoa, 1883: Krakatoa, 1883: tsunamis killed 30,000 people; Santorini, 2002).tsunamis killed 30,000 people; Santorini, 2002).

Mass MovementMass Movement ( (e.g. e.g. Alaska, 1958: waves up to Alaska, 1958: waves up to 518 m high formed in Lituya Bay).518 m high formed in Lituya Bay).

Extraterrestrial ImpactsExtraterrestrial Impacts - large impacts have the - large impacts have the potential to create enormous tsunamis.potential to create enormous tsunamis.

Tsunami Earthquake SourcesTsunami Earthquake Sources Earthquakes that suddenly uplift or down-drop Earthquakes that suddenly uplift or down-drop

the sea floor generate tsunamis. the sea floor generate tsunamis. Generally such surface deformation is largest for Generally such surface deformation is largest for

reverse and normal faulting earthquakes, and reverse and normal faulting earthquakes, and small for transform faulting events thus the small for transform faulting events thus the potential for tsunamis is lower for strike slip potential for tsunamis is lower for strike slip faults faults (e.g(e.g. the Balleny earthquake 1998 did not . the Balleny earthquake 1998 did not generate a tsunami). In general tsunami are generate a tsunami). In general tsunami are generated by reversal faults.generated by reversal faults.

Tsunami GenesisTsunami Genesis Tsunamis are Tsunamis are

caused by events caused by events that drastically and that drastically and suddenly shift a suddenly shift a large volume of large volume of water.water.

From Plummer McGeary Carlson

Tsunami EarthquakesTsunami Earthquakes Some earthquakes have generated very Some earthquakes have generated very

large tsunamis for their “size”. These large tsunamis for their “size”. These events are called events are called tsunami earthquakestsunami earthquakes.. Analysis of seismograms from these events Analysis of seismograms from these events

suggest that they are the result of low-suggest that they are the result of low-frequency seismic energy.frequency seismic energy.

These earthquakes present a problem for These earthquakes present a problem for tsunami warning systemstsunami warning systems

Tsunami EarthquakesTsunami Earthquakes One way to identify these events is to One way to identify these events is to

compare Ms to Mwcompare Ms to Mw Ms ~ 20 seconds periodMs ~ 20 seconds period Mw ~ 100-200 seconds periodMw ~ 100-200 seconds period

Since the signals are enriched in long Since the signals are enriched in long periods the magnitude is unusually larger periods the magnitude is unusually larger than the Ms estimate. than the Ms estimate.

Standard Earthquake

M~7.0

Slow-source Tsunami Earthquakemb ~5.8, MS ~7.2, MW~7.7

An earthquake with a big An earthquake with a big vertical component is more vertical component is more “tsunamogenic” than a purely “tsunamogenic” than a purely horizontal event.horizontal event.

“Slow” events with a long “Slow” events with a long duration are also sources of duration are also sources of larger tsunamislarger tsunamisFrom E. Okal

Describing Ocean WavesDescribing Ocean Waves Ocean wavesOcean waves are deformations of the sea surface. are deformations of the sea surface. Wavelength: Wavelength: distance between crests (distance between crests ()) Wave height: Wave height: vertical distance between crest and vertical distance between crest and

troughtrough Period: Period: time between 2 successive crests to pass (T)time between 2 successive crests to pass (T)

Describing Ocean WavesDescribing Ocean Waves The deformation propagates with the wave speed while on average water The deformation propagates with the wave speed while on average water

remains in the same position (the water does not pile up on the beach).remains in the same position (the water does not pile up on the beach). Water moves in the propagation direction at the crest while moving in the Water moves in the propagation direction at the crest while moving in the

opposite direction at the through.opposite direction at the through. Water of a deep-water wave moves in a circular orbit on a circle Water of a deep-water wave moves in a circular orbit on a circle

which diameter is decreasing downward. The motion become which diameter is decreasing downward. The motion become negligible at a depth of ~ half wavelength.negligible at a depth of ~ half wavelength.

Describing Ocean WavesDescribing Ocean Waves Energy moves in the propagation direction.Energy moves in the propagation direction. Most ocean waves are produced by wind bringing the Most ocean waves are produced by wind bringing the

energy from the wind offshore toward the coast.energy from the wind offshore toward the coast. The rate at which a wave loses its energy is inversely The rate at which a wave loses its energy is inversely

related to its wavelength. Long-wavelength waves related to its wavelength. Long-wavelength waves can travel further.can travel further.

Describing Ocean WavesDescribing Ocean Waves Deep water waves Deep water waves are surface waves.are surface waves. Deep Water:Deep Water: the water depth where a wave passing the water depth where a wave passing

overhead is not discernable at the sea bed.overhead is not discernable at the sea bed. Deep Water Waves: Deep Water Waves: the wavelength is < 1/2 Water the wavelength is < 1/2 Water

depth (D)depth (D)

Describing Ocean WavesDescribing Ocean Waves Wind Waves:Wind Waves: T~ 10-20s T~ 10-20s ~10-600m~10-600m Deep Water Velocity:Deep Water Velocity: v= v=/T (v~1-30m/s)/T (v~1-30m/s) The speed of deep water waves depends on The speed of deep water waves depends on

wavelength, deep water waves are wavelength, deep water waves are dispersivedispersive.. Shallow Water VelocityShallow Water Velocity: :

€

v = gλ2π

tanh 2πDλ

⎛ ⎝ ⎜

⎞ ⎠ ⎟ ≈d< L

20cgD

Describing Ocean WavesDescribing Ocean Waves Shallow Water Velocity:Shallow Water Velocity:

The shallow water velocity does not depend on wavelength. The shallow water velocity does not depend on wavelength. Shallow water wavesShallow water waves do not show dispersion. do not show dispersion.

As the wave approaches shallow water the shape of the As the wave approaches shallow water the shape of the motion becomes more elliptical and the velocity slows down. motion becomes more elliptical and the velocity slows down. To conserve energy the wave rises higher. To conserve energy the wave rises higher. €

v = gD

Describing Ocean WavesDescribing Ocean Waves Tsunami Wave: Tsunami Wave: T~3600 s T~3600 s ~800 km ~800 km Since the ocean has an average depth of 5 km it is always Since the ocean has an average depth of 5 km it is always

a shallow water wave, the velocity is increasing with ocean a shallow water wave, the velocity is increasing with ocean depth. (friction with the bottom lower) depth. (friction with the bottom lower)

Typical tsunami wave velocity (water depth 5000m) v~220 Typical tsunami wave velocity (water depth 5000m) v~220 m/s = 792 km/hr (cruise velocity Jumbo 747 ~800km/hr) m/s = 792 km/hr (cruise velocity Jumbo 747 ~800km/hr)

€

v = gD

Describing Ocean WavesDescribing Ocean Waves Tsunami Wave: Tsunami Wave: T~3600 s T~3600 s ~800 km ~800 km Since the long-wavelength waves lose less energy a tsunami Since the long-wavelength waves lose less energy a tsunami

can travel transoceanic distances with only limited energy loss.can travel transoceanic distances with only limited energy loss. In the deep ocean the amplitude of a tsunami is a few cm to few In the deep ocean the amplitude of a tsunami is a few cm to few

dm on a very long wavelength:dm on a very long wavelength: it is not felt aboard a ship or it is not felt aboard a ship or seen from air in open ocean seen from air in open ocean (but can be measured by buoy or (but can be measured by buoy or satellite altimeter).satellite altimeter).

When a tsunami approaches the shoreline the velocity When a tsunami approaches the shoreline the velocity decreases (D diminish) and in order to conserve energy decreases (D diminish) and in order to conserve energy (proportional to v and H) the amplitude increases.(proportional to v and H) the amplitude increases.

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HD12

HD22 = vD2

vD1

=gD2

gD1

From UNESCO/PTWC tsunami booklet

An ExampleAn Example Tsunami Wave Tsunami Wave Example: Sumatra 2004 Example: Sumatra 2004 How long does it take to get to Sri Lanka?How long does it take to get to Sri Lanka?

Distance ~1600 kmWater Depth ~4000 m

T= 2000/713=2.2 hr

€

v = gD ≈ 9.8 * 4000 =198ms

= 713 kmhr

An ExampleAn Example Tsunami Wave Tsunami Wave Example: Sumatra 2004 Example: Sumatra 2004 How long to get to Thailand?How long to get to Thailand?

Distance ~500 kmWater Depth ~1500 m

T= 500/430=1.1 hr

€

v = gD ≈ 9.8 *1500 =120ms

= 430 kmhr

An ExampleAn Example Tsunami Wave Tsunami Wave Example: Sumatra 2004 Example: Sumatra 2004 ““Correct” numerical model using observed source and high Correct” numerical model using observed source and high

definition bathymetry of the front propagationdefinition bathymetry of the front propagation

Courtesy: K. Satake,

unpublished

An ExampleAn Example Tsunami Wave Tsunami Wave Example: Sumatra 2004 Example: Sumatra 2004 How high is the wave?How high is the wave?

€

HD12

HD22 = vD2

vD1

=gD2

gD1

1

1

2

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HD12

HD22 = 0.62

HD22 =

gD2

gD1

=

= 9.8*109.8* 4000

⇒ HD2 = 7.6m

NOAA

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Describing TsunamisDescribing Tsunamis Tsunami wave height is the height of the Tsunami wave height is the height of the

wave at the shore.wave at the shore. Tsunami run-up height is the maximum Tsunami run-up height is the maximum

height that the wave reaches on land.height that the wave reaches on land.

Tsunami LocationsTsunami Locations Large subduction zones produce the most Large subduction zones produce the most

tsunamis. The Pacific, rimmed with tsunamis. The Pacific, rimmed with subduction zones, has the most tsunamis.subduction zones, has the most tsunamis. Pacific ~ 80%Pacific ~ 80% Atlantic ~ 10%Atlantic ~ 10% Elsewhere ~ 10%Elsewhere ~ 10%

Tsunami PropagationTsunami Propagation Tsunamis are most devastating near the Tsunamis are most devastating near the

earthquake. They are larger and strike the earthquake. They are larger and strike the region soon after the earthquake.region soon after the earthquake.

They also travel across entire oceans and They also travel across entire oceans and cause damage and death thousands of cause damage and death thousands of miles from the earthquake.miles from the earthquake.

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Local Tsunami DamageLocal Tsunami Damage Damage close to the tsunami is usually more Damage close to the tsunami is usually more

devastating. devastating. Even small events can generate locally high waves. Even small events can generate locally high waves.

(For example in a bay the waves can be focused (For example in a bay the waves can be focused and increase their amplitude, a landslide triggered and increase their amplitude, a landslide triggered by an earthquake in a fiord in Alaska in 1958 by an earthquake in a fiord in Alaska in 1958 created waves with a run-up up to 518 m high).created waves with a run-up up to 518 m high).

The warning time can be dramatically short.The warning time can be dramatically short.

Wave diffractionWave diffraction Waves that pass from a media where they move Waves that pass from a media where they move

fast to a media where they move more slowly, are fast to a media where they move more slowly, are refracted, and waves that move around obstacles, refracted, and waves that move around obstacles, are diffracted. This can highly influence the local are diffracted. This can highly influence the local damages resulting from the waves.damages resulting from the waves.

Bascom, 1964

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86 feet = 26 m

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Tsunami WarningTsunami Warning Because tsunamis travel relatively slowly, Because tsunamis travel relatively slowly,

we have a chance to warn distant regions we have a chance to warn distant regions of potential tsunamis.of potential tsunamis. These efforts provide strong arguments for These efforts provide strong arguments for

real-time earthquake monitoring.real-time earthquake monitoring. Alerts are issued routinely by cooperating Alerts are issued routinely by cooperating

governments.governments. Check out:Check out:

• http://wcatwc.gov/http://wcatwc.gov/

Tsunami WarningTsunami Warning As soon as an earthquake of magnitude >6.5 is As soon as an earthquake of magnitude >6.5 is

located in the sea the alarm start.located in the sea the alarm start. Using computer simulations and maps like the Using computer simulations and maps like the

one in the following slide scientists forecast the one in the following slide scientists forecast the time of arrival in different locations.time of arrival in different locations.

Tsunami Travel Times Tsunami Travel Times (Hawaii)(Hawaii)

From Merritts et al., 1998


located in the sea the alarm start.located in the sea the alarm start. Using computer simulations and maps like the Using computer simulations and maps like the

one in the following slide scientists forecast the one in the following slide scientists forecast the time of arrival in different locations.time of arrival in different locations.

The use of Buoy and tide gauges help to verify The use of Buoy and tide gauges help to verify the effective presence of a tsunami, the alarm is the effective presence of a tsunami, the alarm is given.given.


located in the sea the alarm start.located in the sea the alarm start. Using computer simulations and maps like the one in Using computer simulations and maps like the one in

the following slide scientists forecast the time of the following slide scientists forecast the time of arrival in different locations.arrival in different locations.

The use of Buoy and tide gauges help to verify the The use of Buoy and tide gauges help to verify the effective presence of a tsunami, the alarm is given.effective presence of a tsunami, the alarm is given.

Once that the alarm is given is necessary that the Once that the alarm is given is necessary that the local communities have emergency plans, that they local communities have emergency plans, that they receive the messages, and that the population receive the messages, and that the population knows what to do knows what to do

Sumatra Tsunami 2004Sumatra Tsunami 2004

A emergency reaction example (thanks to Benz, USGS)

Propagation, Response and Warning Times for the M9.0 Sumatra EQ

9090 100

0

1 minutes after OT

Northern SumatraPeople are sensing severeshaking

NEICNo information regarding earthquake

PTWCNo information regarding earthquake and/or tsunami

P S


10 minutes after OT

Northern SumatraSignificant structural damagein Banda Aceh

Tsunami inundation along the Sumatran coast

EQ is widely felt throughout the region

NEICShort period alarm on eight stations in the region

PTWCShort period alarm on western Pacific stations

P S

Short-period alarm stations

10 minutes after OT


90

0

12 minutes after OT

Northern SumatraTsunami inundation spreadsfurther along the Sumatran coast

NEICShort period alarm on sixteen stations In the region

Mb6.2, Mwp8.2 earthquakelocated off the north coast ofSumatra

Pager notification to dutyseismologists and others atNEIC

PTWCMwp8.2 earthquake locatedoff the north coast of Sumatra

No tsunami advisor for thePacific Ocean

P S


16 minutes after OT

P S

Northern SumatraTsunami inundation spreadsfurther along the Sumatran coast and reaches theNicobar Islands

NEICFirst automatic location releasedat NEIC

Pager notification to about 10people in the USGS

PTWCConfers with NEIC on the location and magnitude of theEarthquake

Release Tsunami Information Bulletin

01:14 WC&ATWC Tsunami Information Bulletin

Location 3.4 N, 95.7 EBASED ON LOCATION AND MAGNITUDE THE EARTHQUAKE WAS NOT SUFFICIENT TO GENERATE A TSUNAMI DAMAGING TO CALIFORNIA - OREGON - WASHINGTON - BRITISH COLUMBIA OR ALASKA. SOME AREAS MAY EXPERIENCE SMALL SEA LEVEL CHANGES. IN AREAS OF INTENSE SHAKING LOCALLY GENERATED TSUNAMIS CAN BE TRIGGERED BY SLUMPING. THE PACIFIC TSUNAMI WARNING CENTER WILL ISSUE TSUNAMI BULLETINS FOR HAWAII AND OTHER AREAS OF THE PACIFIC.

16 minutes after OT

30 minutes after OT

M5.5

34 minutes after OT

M5.5

M6.1

39 minutes after OT

M5.5

M6.1

M6.0

43 minutes after OT

M5.5

M6.1

M6.0

M5.5


90

0

44 minutes after OT

Northern SumatraTsunami is passing thru theNicobar Islands

NEICAutomatic Ms magnitude iscalculated (Ms8.5)

Pager notification to about 30people in the USGS

Aftershocks suggest Ms8.5 istoo low

PTWCConfers with NEIC on the location and magnitude of theearthquake

Notifies US Military on DiegoGarcia on the possibility ofan approaching tsunami


0

90

75 minutes after OT

Northern SumatraTsunami reaches the AndamanIslands, approaches the Thaicoast

NEICReleases reviewedearthquake location andmagnitude (Ms8.5)

Pager notifications are sentto 25,000 people

Call down list is activated

Wire service reportsof collapsed buildings in Banda Aceh

PTWC

Telephone Call-Down List

USGS Earthquake Hazards Program Coordinator 02:30 UTCUSGS Office of Communications02:30USGS NEIS Coordinator 02:25White House situation room 02:35 State Department Operations Center 02:36 FEMA Operations Center 02:37International Commission on Renal Failure, Alberta, Canada 02:39 EERI

02:42USGS GHT Chief Scientist 02:27USGS GHT Chief Scientist 02:29USGS CR Executive for Geology02:32

Msg AgencyPager/Email USGS Earthquake Program, Reston and GoldenPager FEMA, Washington DC areaPager/Email UN Radio Readiness Group, New YorkFax/Email Japan Meteorological Agency, TokyoEmail Schweizerischer Erdbebendienst, Zurich,SwitzerlandEmail Servicio Hidrográfico y Oceanográfico de la Armada, ChileEmail Réseau National de Surveillance Sismique, EOPGS, Strasbourg, FranceEmail Seismic Data Analysis Center, BGR, Hannover, GermanyEmail Russian Academy of Sciences Siberian Branch, Novosibirsk, RussiaEmail GeoForschungsZentrum Potsdam, Potsdam, GermanyEmail US Strategic Air Command, NebraskaEmail National Geospatial Intelligence Agency, VirginiaEmail European-Mediterranean Seismological Centre,

Bruyères-le-Châtel, FranceEmail Instituto Geográfico Nacional, Madrid, SpainEmail World Agency of Planetary Monitoring and EQ Risk

Reduction, Geneva

Recipients of “embassy” news release message(Sent between 02:21 and about 02:30)

Msg. type AgencyFax/Email US Embassy Consular Section,

Jakarta, IndonesiaFax/Email US Consulate General,

Surabaya, IndonesiaFax/Email US Consular Agent, Denpasar,

IndonesiaFax UN Office for the Coordination

of Humanitarian Affairs, Geneva, Switzerland

104 minutes after OT


122 minutes after OT

Indian OceanLittle communication fromBanda Aceh

Destruction in Pkuket

Tsunami hits Sri Lanka

NEICContinuing dialogue betweenUSGS scientists in Golden,Reston and Menlo Park

No confirmation via wireservices of tsunami in theIndian Ocean

Wire service reports of building collapse in BandaAceh

Web content is beingdeveloped and posted

Can We Do Better? Yes

•Improved sensor networks in hazards areas of the world (seismic, tide gauge, ocean buoys) and coordinated distribution and processing of data

•Better information content that can better assist emergency responders to assess the scope of the disaster

•Coordination and integration with national, regional and local emergency response agencies and civil authorities

•Education and training at national, regional and local levels of government and the general population

Tsunami Hazard MitigationTsunami Hazard Mitigation We can warn people of potential tsunamis We can warn people of potential tsunamis

from distant earthquakes. Warning of near from distant earthquakes. Warning of near source tsunamis is much more difficult. source tsunamis is much more difficult.

Prevention of tsunami catastrophes Prevention of tsunami catastrophes requires carefully planned use of low-lying requires carefully planned use of low-lying areas.areas. This is not always possible, or affordable.This is not always possible, or affordable.

Protecting Yourself (Tsunami)Protecting Yourself (Tsunami) Move to higher ground.Move to higher ground. Wait until authorities give the go ahead to Wait until authorities give the go ahead to

return to low-lying regions.return to low-lying regions. Watch for surges of water in rivers and Watch for surges of water in rivers and

streams near the coast.streams near the coast. If you feel a strong earthquake, don’t wait If you feel a strong earthquake, don’t wait

for a formal warning. for a formal warning.

Rivers & LakesRivers & Lakes

Shaking & Rivers & LakesShaking & Rivers & Lakes Tsunamis are an ocean phenomena, but Tsunamis are an ocean phenomena, but

any large body of water can be at risk if a any large body of water can be at risk if a larger part of its water is suddenly larger part of its water is suddenly displaced.displaced.

Collapsing river banks or lake bluffs can Collapsing river banks or lake bluffs can be hazardous to anyone on the water and be hazardous to anyone on the water and disrupt river traffic, which can impact local disrupt river traffic, which can impact local economies.economies.

SeichesSeiches The sloshing of closed bodies of water The sloshing of closed bodies of water

during an earthquake is call a seiche.during an earthquake is call a seiche. Large earthquakes have produced seiches Large earthquakes have produced seiches

observed over large areas.observed over large areas. Although seiches have produced waves Although seiches have produced waves

with a height of a few feet, damage was with a height of a few feet, damage was minimal.minimal.

Landslide in lakesLandslide in lakes A much more serious hazard is a landslide A much more serious hazard is a landslide

that it a lake in particular artificial basins. that it a lake in particular artificial basins. In this case the wave generated can In this case the wave generated can overtop the dam and/or cause the dam overtop the dam and/or cause the dam failure. The results can be devastating failure. The results can be devastating (e.g. Longarone, Italy, 1963, 1917 people (e.g. Longarone, Italy, 1963, 1917 people killed)killed)

Sissano Lagoon - Papua NewGuineaEarthquake Magnitude ~ 7.0Landslide ~ 3-5 km3 [0.6 - 1.0 miles3]

Tsunami 10-15 meters [30 - 50 feet]

1929 Grand BanksEarthquake Magnitude ~ 7.2Landslide ~ 185 km3 [~35 miles3]

Tsunami 4-12 meters [12 - 40 feet]

Mid-Atlantic CoastLandslide ~ 150 km3 [~30 miles3]

Tsunami ??????

New Jersey CoastLandslide ~ 120 km3 [~25 miles3]

Tsunami ??????

Landslide Tsunami

The 2004 Boxing Day Earthquake

1946 Hilo1946 Hilo

Anchorage, Alaska – 1964Anchorage, Alaska – 1964

Photographic sequence Photographic sequence from hotel balcony in from hotel balcony in

Thailand (1 of 2)Thailand (1 of 2)

Photographic sequence (2 Photographic sequence (2 of 2)of 2)

Recognize fraudulent images - Recognize fraudulent images - Don’t be fooledDon’t be fooled

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