Volcano english

7/29/2019 Volcano english

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Tungerahua Volcano, Ecuador

VolcanoesLiquid. Hot. Magma.


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Volcano Statistics

Definition ofVolcano

Mountain that forms when molten rock

(magma) is forced to the Earths surface

Number of active volcanoes= ?

20 erupting right now

(50-60/year) (160/decade) Number of volcanologists=1,500


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World Map of Volcanoes


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Volcanoes per Continent

0

50100

150

200

250

Australi

a

South

Americ

a

North

Americ

aAsia

Europ

e

Africa

Anta

rctica

Australia

South America

North America

AsiaEurope

Africa

Antarctica


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The Worlds Volcanoes

Antarctica

2%

Africa

13%

South

America

11%

NorthAmerica

27%

Europe

4%Australia

6%

Asia

37%


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What causes volcanoes?

The Formation of Magma Mantle rock melts when the

temperature increases

or the pressure decreases.


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Volcanoesform around

vents thatrelease magmaonto the Earths

surface.

Vents

Lava

Magma Chamber


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Where do Volcanoes form?

Most volcanoes form alongtectonic plate boundaries!

~75% of the Worlds active volcanoes are in the Ring of Fire


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Convergent Plate Boundaries, Subduction Zones & Divergent Plate Boundaries


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Some volcanoes are formed aboveHot Spots places where the lithosphere

is thin, allowing hot magma to rise from the

mantle.


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The Hawaiian Islands are formed fromthe Pacific plate moving over a hot spot.

A new island is forming!


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Parts of a Volcano

MainVent

Side Vent

Crater

Lava


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Types of Volcanoes

Shield Volcano

Cinder Cone Volcano

Composite Volcano


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Circular base,

sides havegentle slopes,made of layers

of basalticlava, non-explosive.


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Smallest, steep

sides, ejectedmaterial &

cinders falls

back onto thevolcano.


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Largest, sidesare not as steepas cinder cone,

made offragments pluslava, explosive!


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Volcanic Eruptions

Nonexplosive Eruptions

Explosive Eruptions

What isLava?

-magma that flows ontothe Earths surface

Lava fountain

Lava flow


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The Composition of Magma Determineswhether it is explosive or not!

High water content

More likely to be !!!

High content

More likely to be !!!

Why?

Silica has a thick, stiff consistency

Flows slowly

Tends to Harden in the volcanos vent


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What Eruptsfrom a Volcano?

Lava can bethick or thin.

Blocky lava

Pahoehoe(smooth & ropey)

Aa(rough) Pillow lava

(cools quickly on ocean floor)


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What Erupts from a Volcano?

Pyroclastic material

Rock fragments created by eruptionsmagma explodes from volcano and solidifies in the air

existing rock is shattered by powerful eruptions

Volcanicblocks Volcanic bombs

Volcanic ash


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Craters, Calderas, and Lava Plateau

Craters

Form when material explodes out ofthe vent then collapses back onto

itself, leaving a depression.

CalderasForm a much larger depressionwhen the magma chamber empties

and its roof collapses

Lava PlateausForm when lava erupts from longcracks, or fissures, and spreads out

evenly (thousands of km)


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Types of

Volcanoes

ShieldVolcano

CompositeVolcano

Cinder ConeVolcano

Parcutin,

Mexico

Mt. St. Helens,

Washington

Kilauea,

Hawaii


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Multiple Eruption Volcanoes

Kilauea- HawaiiVesuvius-

Italy

Mt. St. Helen-

Washington

March 2005 March 18, 1944 September 23, 2004

November 2000 79 AD May 18, 1980


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Mount St. Helen


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Mt. Kilauea


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Mt. Parcutin


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How do volcanoes affect the Earth?

Flows and Fallouts

Pyroclastic Flow = deadly, extremely

hot ash and toxic gases, moving at

hurricane-force speeds.Ash Fallout = volcanic ash drifts with

the windCollapse buildings (too much weight)

Dam rivers, leading to flooding ordrought

Smother crops

Choke people and animals

Very abrasive
http://www.geology.sdsu.edu/how_volcanoes_work/Thumblinks/augustine_page.htmlhttp://www.geology.sdsu.edu/how_volcanoes_work/Thumblinks/augustine_page.html


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Climatic Changes

Ash & Gases can block

sunlight

Drop average globaltemperature noticeably

Damage & Destruction

of land & structures Volcanic Soils are rich

in nutrients

How do volcanoes affect the Earth?


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Measuring Small Quakes

Before eruption, increase in number & intensity

Measuring Ground Slope

Bulges may form as magma chamber grows (tilt meter)

Measuring Volcanic Gases in the Atmosphere

Outflow of volcanic gases

Sulfur dioxide, carbon dioxide

Measuring Temperature from Orbit

Measure changes in temperature over time

How do volcanologists predicteruptions?


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You should not be aVolcanologist if.

You dont likehiking,backpacking,

rock-climbing,etc.

You are notinterested inexperiencingextremetemperaturesand heights.

If you dont like

to travel toincredible placesand seebreathtakingviews of the

world

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