volcanism & deposit activity

NED University of Engineering & Technology

Department Of Urban & Infrastructure Engineering

Volcanism Types Of Volcanoes Types Of Deposits Formation and Behaviour Distribution Of Volcanoes Prediction Of Volcanic Eruptions Volcanic Hazards Valcano Advantages Conclusion

Contents

Volcanism Volcanism is the phenomenon of eruption of

molten rock (magma) onto the surface of the Earth

Volcanic Process

Aspects Of Volcanism1. Earthquake2. Volcano

1.Earthquake An earthquake (also known as a quake, tremor

or temblor) is the result of a sudden release of energy in the earth's crust that creates seismic waves. The seismicity, seismism or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time .

Naturally occurring earthquakes

Earthquake fault type

Size and frequency of occurrence

Effects Of Earthquakes

Shaking and ground rupture Landslides Soil liquefaction Tsunami Floods

State Of Volcanoes

• Volcanoes can be active, dormant or extinct.• Volcano is active or alive if at the present time it

is expected to erupt• Volcano is dormant or sleeping that is not

erupting or predicted to erupt in the near future• A volcano is extinct or dead that no one expects

will ever have another eruption

http://www.basicplanet.com/classification-volcanoes/

Active Volcano

• the best examples of this classification of volcanoes would be Kilauea which has been

erupting since 1983.

http://www.basicplanet.com/classification-volcanoes/

Kīlauea is a currently hyperactive shield volcano in the Hawaiian Islands, and the most active of the five volcanoes that together form the island of Hawaiʻi

Dormant Volcano

• Mauna Kea is a volcano which is located on Big Island and its last eruption took place 3,500-4,000 years ago. However scientists believe that it will erupt again

Mauna Kea is a dormant volcano on the island of Hawaii. Standing 4,205 m above sea level

Extinct Volcano

• One such volcano is also located on Hawaii’s Big Island and its name is Kohala. The last time that Kohala erupted was close to 60,000 years ago. As of now scientists do not believe that volcano will ever be active again

Kohala is the oldest of five volcanoes that make up the island of Hawaii. Kohala is an estimated million years old

Types Of Volcanoes

• Classification of volcanoes is done on the basis of shapes, magnitude, structure and materials of different volcanoes also the way these volcanoes erupt.

• There are four different types volcanoes:1. shield volcanoes2. composite volcanoes3. cinder cones4. lava domes

http://www.livescience.com/27295-volcanoes.html

Shield Volcanoes

• Shield volcanoes are very very big in size• Shield volcanoes are shaped like a bowl with long

gentle slopes made by the lava flows.• If the magma is runny, the gas can escape easily

and there will not be an explosion. The magma just comes out of the mountain and flows down the sides that is why they are not so much dangerous.

Muana Loa Volcano – the world’s largest volcano

Mauna Loa is about 55,770 feet from its base, which is 13,681 feet above sea level. It is also one of the Earth’s most active volcanoes and is carefully monitored. The most recent eruption was in 1984.

• Fluid Flow, high temperature, low silica

• shield volcanoes is less viscous, so it flows much more easily. For this reason, the eruptions of shield volcanoes are non-explosive

• They are flat mount

Composite Volcanoes

• Composite Volcanoes (lava and pyroclastic deposits).

• They are known as ‘Strato Volcanoes’.• If the magma is thick and sticky (like honey), the

gas cannot escape, so it builds up and up until it explodes sending out huge clouds of burning rock and gas.

• composite volcanoes eruption is dangerous and explosive in nature. With a lot of layers of lava and pyroclastic materials involved.

• Stratovolcanoes erupt with great violence. • Composite volcanoes are big, they can range from

1 – 10 km in diameter

Stratovolcanoes are considered the most violent eruptions. Mount St. Helens, in Washington state, erupted on May 18, 1980. Approximately 230 square miles of forest was completely Destroyed and 57 people were killed. Ash was blown up into the atmosphere and fell over 11 states.

Cinder cones Volcanoes

• Cinder cones are the most common type of volcano and also the smallest

• Cinder cones are circular or oval cones built from erupting lava that breaks into small pieces As small pieces fall back to the ground, they cool and form cinders around the vent.

http://ete.cet.edu/gcc/?/volcanoes_types/

Paricutin in Mexico

• Parícutin is a cinder cone volcano in the Mexican state of Michoacán

• The volcano is unique in the fact that its evolution from creation to extinction was witnessed

• Last Eruption: 1952

single opening. The opening of a cinder cone is a cone-shaped structure, while the steeps are formed of the erupted, fragmented cinders that fall close to the chimney/vent.

Lava DomesVolcanoes

• Lava domes are formed when erupting lava is too thick to flow and makes a steep-sided mound as the lava piles up near the volcanic vent.

Kelud Volcano-Indonesia

Kelud is a volcano located in East Java on Java in Indonesia. Like many Indonesian volcanoes and others on the Pacific Ring of Fire, Kelud is known for large explosive eruptions throughout its history

• lava domes are formed when the lava is too viscous to flow to a distance so it continues to pile within. As the lava dome keeps growing, the outer surface starts to cool and become hardened. When a lava dome is grown to a significant extent, it shatters the outer surface, which results in spilling loose fragments.

Volcanic Deposits Result of materials like rock and gases emitted

from a volcanic eruption. Result of magma to break through to the

surface.

Types Of Deposits1. Lava: Hot (up to 1200 degrees C) , fluid, molten rock that flows along the land surface.

2.Pahoehoe

Basaltic lava that has a smooth, hummocky, or ropy surface

2.1: Ropy Pahoehoe

ropy pahoehoe form when the thin, partially solidified crust of a flow is slowed or halted

2.2:Coil Pahoehoe Lava coils are spiral or scroll-shaped features that are formed along slow-moving shear zones in a flow.

2.3:Aa Blocky, rough lava solid flow. Due to high

viscosity lava that flowed pushing chunks of and semi-solid blocks.

3:Lava tube: A tube formed by cooling

and solidifying of the lava walls while fluid lava continued to flow inside.

3.1:Pillows: A form of closed lava

tube (with a bulbous end) that when a lava flows into water (e.g., a lake or ocean) and cools very rapidly

4:Tephra

The general term for all pyroclastic material.

Different terms apply according to the size of the

tephra. 4.1.1: Lapilli: from 2 mm to 64 mm in diameter 4.1.2:Ashtephra that is finer than 2 mm in diameter

4.1:Types of tephra

1.Magma Formation

Magma is a mixture of molten or semi-molten rock, volatiles and solids that is found beneath the surface of the Earth, and is expected to exist on other planets.

2.Magma Viscosity Composition Temperature Silicon Content H2O Content

3- Gases Evolved During Eruption

1- Water Vapour2- Carbon dioxide3- Sulphur Dioxide4- Hydrogen Fluoride5- Hydrogen Chloride

Sites where magma is erupted

Places where magma is erupted are known as Vent or Crater.In Pakistan recents volcanic erruption took place in

Distribution Of Volcanoes

1: Plate Boundries

2: Volcanic Belts

2.1: Circum Pacific Belt Ring of fire

South America ,Central America , Maxico, Mountains of United States , Japan , Philipines , New zealand

2.2: Mid-Continental Belt

Mediterranean sea , Hindu kush

Emit steam and other gases

Extinct volcanoes

2.3: MidAtlantic Belt

Prediction Of Volcanic Eruptions

1:Long Term Prediction• Identify volcanoes and the frequency and style of

their eruptions. • Establish probabilities of eruption, style and

location for individual volcanoes.• Establish the level of risk based on historic and

geologic record. • E.g., for individual volcanoes: determine most

likely routes for lahars, lava flows, etc., and avoid construction in those areas.

Hazard zones have been distinguished around Mt. Shasta based on topography and past experience with eruptions.

Zone 1: areas likely to be affected most frequently. Most future flows from summit eruptions probably would stay within this zone.

Zone 2: areas likely to be affected by lava flows erupted from vents on the flank of the volcano or that move into zone 2 from zone 1.

Zone 3: areas likely to be affected infrequently and then only by long lava flows that originate at vents in zones 1 and 2

.

2: Short-term Prediction

Based on the recognition of a pattern of events prior to previous eruptions.

Gas emissions: rates of emission and type of gas changes in some volcanoes.

Important gases include sulfur dioxide (SO2) and carbon dioxide (CO2)

Changes in concentration may reflect movement of the magma up the vent.

Earthquakes: generated as the magma moves up the feeder conduit to the vent.

When viscous magma becomes stuck in the conduit

strain energy builds as more magma tries to push out.

Movement takes place in a series of “jerks” as the rock material breaks. Each “jerk” produces an earthquake.

Magnitudes generally less than 5 m.

The more earthquakes the further the magma has moved.

The more earthquakes the further the magma has moved.

Volcanic Hazards Volanoes give rise to numerous geologic

and hydrologic hazards.

The most volcanically active regions of the nation are in Alaska , Hawaii ,california, oregon, and washington .

Large explosive eruptions can endanger people and property hundreds of miles away and even affect global climate .

Volcanic gases volcanic emit gases during

eruptions.

Even when a valcano is not erupting cracks in the ground allow gases to reach the surface through small opening fumaroles .

Carbon dioxide is heavier than air and can be trapped in low areas in concentrations are deadly to people and animals .

Earthquake Due To Volcano

It occur due volcanic activity.

Produced by stress change in solid rock due to withdrawal of magma

When magma suddenly forced into surrounding rocks .

Eruption columns and clouds

Explosive eruption blast solid and molten rocks fragments .

The largest rocks fragments usually fall back to ground within two miles of vent

Small fragments of volcanic glass, minerals and rock rise high into the air

Pyroclastic flows High speed avalanches of

hotash , rock fragments and gases can move down the slide of volcano

These flows can be hot and move at speed 100 to 150 miles per hour

Such flows tend to follow valley and capable of knocking down and burning every thing in their path .

Advantages Of VolcanismGeothermal Energy Geothermal energy means heat energy from the

earth.

The heat from underground steam is used to drive turbines and produce electricity, or to heat water supplies that are then used to provide household heating and hot water.

Where steam doesn't naturally occur it is possible to drill several deep holes into very hot rocks, pump cool water down one hole and extract steam from another hole

Countries such as Iceland make extensive use of geothermal power, with approximately two thirds of Iceland's electricity coming from steam powered turbines.

Iceland has over 200 volcanoes and 800 hot springs

Minerals Magna rising from deep inside the earth contains

a range of minerals.

This means that minerals such as tin, silver, gold, copper and even diamonds can be found in volcanic rocks.

Hot gasses escaping through Vents of active volcanoes also Bring minerals to the surface, Notably sulphur, which collects Around the vents as it Condenses and solidifies.

Volcanic rocks are often used in construction.

As early as 300 bce, romans made concrete from volcanic ash and lime.

This material was used to build the colosseum in rome in 80 ce. The strength of this material has allowed the colosseum to stand for nearly two thousand years

Geothermal water can be used to drive turbines that generate electricity.

It can also be used to heat homes, grow crops, or keep roads free of ice.

Fertile Soils Volcanic rocks are rich in minerals, but when the

rocks are fresh the minerals are not available to plants.

The rocks need thousands of years to become weathered and broken down before they form rich soils.

When they do become soils though, they form some of the richest ones on the planet.

The Naples area, which includes Mount Vesuvius, has such rich soils thanks to two large eruptions 35,000 and 12000 years ago. Both eruptions produced very thick deposits of ash and broken rocks which have weathered to rich soils

Pumice is added to soil to allow air and water to circulate more easily through the soil.

Because metals in pumice are not water soluble, pumice is used alone or with silica sand to filter drinking water.

As recently as the 20th century, volcanic ash was used to make concrete for dams in the United States.

Today, basalt and pumice are often used in the construction of roads and bridges, and the production of concrete.

References www.bbc.co.uk  www.preservearticles.com www.geologywestcountry.blogspot.com www.USGS.com http://www.basicplanet.com/classification-

volcanoes/ http://www.livescience.com/27295-volcanoes.html http://ete.cet.edu/gcc/?/volcanoes_types/ en.wikipedia.org/wiki/Earthquake