8/6/2019 Ekta Volcano 2003

1/25

VolcanoesLiquid Hot Magma.

MADE BY :-

SHEETAL

8/6/2019 Ekta Volcano 2003

2/25

What is a volcano?

A volcano is a vent or

'chimney' that connectsmolten rock (magma)from within the Earths

crust to the Earth'ssurface.

The volcano includes the

surrounding cone oferupted material.

vent

cone

magma

chamber

conduit

8/6/2019 Ekta Volcano 2003

3/25

8/6/2019 Ekta Volcano 2003

4/25

The Composition of Magma Determines

whether it is explosive or not!

High water content

More likely to be Explosive!!! High Silica content

More likely to be Explosive!!!

8/6/2019 Ekta Volcano 2003

5/25

What Erupts from a

Volcano?

Lava can be

thick or thin.

Blocky lava

PahoehoeAa

Pillow lava

8/6/2019 Ekta Volcano 2003

6/25

What Erupts from a Volcano?

Pyroclastic material Rock fragments created by explosive eruptions

magma explodes from volcano and solidifies in the air

existing rock is shattered by powerful eruptions

Volcanic blocks

Volcanic bombs

Lapilli

Volcanic ash

8/6/2019 Ekta Volcano 2003

7/25

How do volcanoes affect the Earth?

Flows and Fallouts

hot ash can flow really quicklyKnock down buildings

Dam rivers (flooding/drought)Kill crops and livestock

Climatic Changes

Ash & Gases can block sunlightDrop average global temperature

noticeably

8/6/2019 Ekta Volcano 2003

8/25

8/6/2019 Ekta Volcano 2003

9/25

8/6/2019 Ekta Volcano 2003

10/25

Volcanoes that build up

from many slow, steady,flows of hot lava, are

called shield volcanoes.

This kind of volcano is low

and broad with gently

sloping sides. They looklike a warriors shield.

8/6/2019 Ekta Volcano 2003

11/25

8/6/2019 Ekta Volcano 2003

12/25

CinderCone

Volcanoes

8/6/2019 Ekta Volcano 2003

13/25

Cinder cone volcanoes form when

solid rock and ash shoot up into

the air and fall back around thevolcano opening. The cinder cone

volcano has steeply sloped sides.

8/6/2019 Ekta Volcano 2003

14/25

8/6/2019 Ekta Volcano 2003

15/25

Strato

or CompositeVolcanoes

8/6/2019 Ekta Volcano 2003

16/25

Strato volcanoes, also calledcomposite volcanoes, erupt with

molten lava, solid rock, and ash.

The layers pile up much like layersof cake and frosting. The layers

form into symmetrical cones, and

the slopes are steep.

8/6/2019 Ekta Volcano 2003

17/25

8/6/2019 Ekta Volcano 2003

18/25

Craters, Calderas, and Lava

Plateau

Crater From explosions ofmaterial out ofthe vent and the collapse ofmaterial

back into vent

Caldera Much larger depression thatforms when magma chamber

empties and its roofcollapses

Lava Plateau

Forms when lava erupts from long cracks, orfissures,and spreads out evenly (thousands ofkm)

8/6/2019 Ekta Volcano 2003

19/25

8/6/2019 Ekta Volcano 2003

20/25

What causes volcanoes?

Where Volcanoes Form Tectonic Plate Boundaries!!!

~75% worlds active volcanoes in Ring ofFire

8/6/2019 Ekta Volcano 2003

21/25

What causes volcanoes?

8/6/2019 Ekta Volcano 2003

22/25

What causes volcanoes?

Hot Spots

8/6/2019 Ekta Volcano 2003

23/25

How do volcanologists predict eruptions?

Measuring Small Quakes

Before eruption, increase in number & intensity

Measuring Slope

Bulges may form withmagma (tiltmeter)

Measuring Volcanic Gases

Outflow of volcanic gases

Sulfur dioxide, carbon dioxide

Measuring Temperature from Orbit

Measure changes in temperature over time

8/6/2019 Ekta Volcano 2003

24/25

Summary

Volcanoes are extremely hazardous.

However, the volcano can be studied,

monitored and understood.

Each volcano is different, and offers a uniqueset of dangers

Plans may be emplaced to help control

potential damage.

8/6/2019 Ekta Volcano 2003

25/25