Volcanoes Volcanoes are are

Hot StuffHot StuffByBy

Shana Huffaker And Doreen SnyderShana Huffaker And Doreen Snyder

Modified by Mr. KennedyModified by Mr. Kennedy

What is a Volcano?What is a Volcano?

• Volcano- Areas of earth’s surface through which magma and volcanic gases pass

• Volcano comes from the Roman word Vulcan, which means “fire”

Magma rises because it is less dense than the solid rock around it.

What are the parts of a What are the parts of a Volcano?Volcano?

1. VENT- the vent is the opening from which lava flows. Dust, ash, and rock particles can also be thrown out of the vent!

A lava flowlava flow is the area covered by lava as it pours out of a vent

A cratercrater is a bowl-shaped area that may form at the top of a volcano around the central vent

Craters, Calderas, and Lava Plateau

Crater• From explosions of material out of the vent and the collapse of material back into vent

Caldera• Much larger depression that forms when magma chamber empties and its roof collapses

Lava Plateau• Forms when lava erupts from long cracks, or fissures, and spreads out evenly (thousands of km)

How are How are volcanoes volcanoes formed?formed?

Deep in the earth it is very hot. It is so hot that rocks melt. The melted rock is called

magma. The magma is lighter

than the rocks around it so it rises. Sometimes it finds a crack or hole in the earth’s crust and

bursts through. This is how a volcano

begins.

Why do Why do volcanoes volcanoes

erupt?erupt?

Pressure builds deep in Pressure builds deep in the earth where the the earth where the

magma is. Suddenly the magma is. Suddenly the gases escape and gases escape and

violently explode. It is violently explode. It is kind of like toothpaste kind of like toothpaste squirting out of a tube squirting out of a tube when you give it a hard when you give it a hard

squeeze.squeeze.

What are the What are the different kinds of different kinds of

volcanoes?volcanoes?

Volcanoes do not all look Volcanoes do not all look alike. Their shape is alike. Their shape is

based on what type of based on what type of materials they erupt. materials they erupt. There are three main There are three main kinds, or shapes, of kinds, or shapes, of

volcanoesvolcanoes. .

3. Volcanic cone- is the pile of lava, dust, ashes, and rock around the vent. It can be found in different shapes!

Types of Volcanoes

Shield volcano

Cinder cone volcano

Composite volcano

ShieldShieldVolcanoesVolcanoes

Volcanoes that build up Volcanoes that build up from from

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

called shield volcanoes. called shield volcanoes. This kind of volcano is This kind of volcano is

low and broad with low and broad with gently sloping sides. gently sloping sides.

They look like a They look like a warriors shield.warriors shield.

Shield VolcanoShield Volcano

• Is wide and somewhat flat.

• It forms from a quiet eruption.

• Lava flows out quietly and for great distances.

Cinder Cone Cinder Cone VolcanoesVolcanoes

Cinder cone volcanoes Cinder cone volcanoes form when solid rock form when solid rock and ash shoot up into and ash shoot up into the air and fall back the air and fall back around the volcano around the volcano

opening. The cinder opening. The cinder cone volcano has cone volcano has

steeply sloped sides.steeply sloped sides.

Cinder Cone VolcanoCinder Cone VolcanoHas tall, very steep sides.

Has explosive eruptions.

This eruption produces a lot of cinder and ash.

Strato Strato or Composite or Composite

VolcanoesVolcanoes

Strato volcanoes, also Strato volcanoes, also called composite called composite

volcanoes, erupt with volcanoes, erupt with molten lava, solid rock, molten lava, solid rock,

and ash. The layers and ash. The layers pile up much like layers pile up much like layers of cake and frosting. of cake and frosting. The layers form into The layers form into

symmetrical cones, and symmetrical cones, and the slopes are steep.the slopes are steep.

Composite VolcanoComposite Volcano

Form from explosive eruptions.

Produce a lot of lava and ash.

Is small, with steep sides.

What’s inside a volcano?What’s inside a volcano?

• Magma Chamber- molten rock that feeds a volcano

• Vents- cracks in the crust

• What is the difference between magma and lava?

Types of VolcanoesTypes of Volcanoes

• Shield Volcano

a) Built from layers of lava

b) Non-explosive eruptions

c) Not very steep, but can be big

Types of VolcanoesTypes of Volcanoes

• Cinder Cone Volcano

a) Built from pyroclastic material

b) Moderately explosive, short eruptions

c) Small in size, steep slopes

Types of VolcanoesTypes of Volcanoes

• Composite Volcanoes

a) Most common type

b) Explosive eruptions and lava flow

c) Built from pyroclastic material AND lava

What Erupts from a Volcano?

Lava can be thick or thin.

Blocky lava

PahoehoeAa

Pillow lava

What Erupts from a Volcano?

Pyroclastic material• Rock fragments created by eruptions

•magma explodes from volcano and solidifies in the air•existing rock is shattered by powerful eruptions

Volcanic blocks

Volcanic bombs

Lapilli

Volcanic ash

• Measuring Small Quakes– Before eruption, increase in number & intensity

• Measuring Slope– Bulges may form with magma (tiltmeter)

• Measuring Volcanic Gases– Outflow of volcanic gases

• Sulfur dioxide, carbon dioxide

• Measuring Temperature from Orbit– Measure changes in temperature over time

How do volcanologists predict How do volcanologists predict eruptions?eruptions?

There is much more about There is much more about volcanoes out there. Look volcanoes out there. Look

in books and on the in books and on the internet . Have Fun!internet . Have Fun!

Pictures, Images, and information From:Soames Summerhays/Photo Researchers, Inc.

Kraft-Explorer/Photo Researchers Inc.Masao Hayashi-Dung/Photo Researchers Inc.

Why Do Volcanoes Blow Their Tops? By Melvin and Gilda Berger

www.usgs.gov/education/learnweb/volcano/index.html