Volcanic Eruptions

GLOSSARYBomb – a lump of rock thrown out in an eruptionCrater – a deep hollow at the top of a volcanoCrust – The top layer of the EarthEruption – the release of gases, magma and rock from a

volcanoLava – melted rock that flows down the volcanoMagma – melted rock inside the EarthMolten – melted, liquidVent – a crack on the side of a volcano where magma can

escape

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What is a volcano?

• A volcano is a vent or 'chimney' that connects molten rock (magma) from within the Earth’s crust to the Earth's surface.

• The volcano includes the surrounding cone of erupted material.

vent

cone

magma chamber

conduit

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How and why do volcanoes erupt?

• Hot, molten rock (magma) is buoyant (has a lower density than the surrounding rocks) and will rise up through the crust to erupt on the surface.– Same principle as hot air rising, e.g. how a hot air balloon works

• When magma reaches the surface it depends on how easily it flows (viscosity) and the amount of gas (H2O, CO2, S) it has in it as to how it erupts.

• Large amounts of gas and a high viscosity (sticky) magma will form an explosive eruption!– Think about shaking a carbonated drink and then releasing the

cap.• Small amounts of gas and (or) low viscosity (runny) magma will

form an effusive eruption– Where the magma just trickles out of the volcano (lava flow).

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• Three products from an explosive eruption– Ash fall– Pyroclastic flow– Pyroclastic surge

Explosive Eruptions

Pyroclastic flows on Montserrat, buried the capital city.

Parts of Volcanoes

Main Vent

Side Vent

Crater

Lava

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(DEAD)

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ACTIVE VOLCANOES-which are likely to erupt at any moment.DORMANT VOLCANOES-which lie dormant for centuries, but then erupt violently and silently.EXTINCT VOLCANOES -no longer likely to erupt.

SUM UP :-

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Types of Volcanoes

Types of Volcanoes

Shield Volcano

Kilauea,Hawaii

CompositeVolcano

Mt. St. Helens, Washington

Cinder ConeVolcano

Parícutin, Mexico

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Shield volcanoes can span across hundreds of miles and they can be huge vertically that they can reach the clouds of earth very easy. Shield volcanoes have a slow slope and consist of frozen lava after it is hardened. Shield volcanoes almost always have large craters at their summit.

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Mt. Kilauea

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Cinder cone volcanoes consist of mostly loose, grainy cinders and have very little to no lava. Cinder cone volcanoes are normally small about a miles span and about one thousand feet vertically. Cinder cone volcanoes have fairly steep slopes and normally have a small crater at the top.

CINDER CONE VOLCANO

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Mt. Parícutin

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Composite volcanoes have another name called “Strato Volcanoes.” Composite volcanoes consist of lava that is mixed with sand or gravel which in turn creates cinders or volcanic ash.

COMPOSITE VOLCANO

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Mount St. Helen

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Volcanoes around the world

Volcanoes per Continent

050

100150200250

Austra

lia

South

Am

erica

North

Am

erica

Asia

Europ

e

Africa

Antar

ctica

Australia

South America

North America

Asia

Europe

Africa

Antarctica

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Volcanoes Around the world

Antarctica2%

Africa13%

South America

11%

North America

27%

Europe4%

Australia6%

Asia37%

GRAPHICAL PRESENTATION

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World Map of Volcanoes

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Multiple Eruption volcanoes

Kilauea- Hawaii

Vesuvius-Italy

Mt. St. Helen- Washington

March 2005March 18,

1944September 23,

2004

November 2000 79 AD May 18, 1980

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