The Wonderful World of Volcanoes!

By: Ashley Duibley & Elissa Sillars

Fun Facts!• There are over 1,500 volcanoes • 80 of those are under oceans• Indonesia has the most volcanoes • Volcanoes are mountains that grow larger with time due

to the build up of lava and magma on their surfaces• The name "volcano" has its origin from the name of

Vulcan, a god of fire in Roman mythology.• Lava cools slowly because lava is a poor conductor of

heat. Lava flows slow down and thicken as they harden • The world's largest, active volcano is Mauna Loa in

Hawaii, where famous coffee is grown in the rich volcanic soils.

• Did you know that Hawaii was formed by 5 volcanoes. Mauna Loa, and Kilauea are the only active volcanoes.

What Causes Volcanoes??

• Volcanoes release the pressure that builds up under the Earth’s surface

• Volcanoes happen when magma rises to the surface of the earth, which causes bubbles of gas(carbon monoxide) to appear in it.

• They emit gases some being dangerous to humans if they are embedded within the soil

• A few gases released are sulfur dioxide, hydrogen chloride, hydrogen fluoride, and carbon dioxide.

• This gas can cause pressure to build up in the mountain, and it eventually explodes or errupts.

• When the magma bursts out of the earth, it is called lava

Volcano Vocabulary

• Active volcano- is one that erupts regularly.• Dormant volcano- is one that has not erupted

for many years, although there is still some activity deep inside.

• Volcanic eruption- is when hot rocks and lava burst from a volcano.

• Magma- is liquid rock inside a volcano. • Lava- is liquid rock that flows out of a volcano.• Geysers- are springs that throw boiling water

high in the air. They are caused by volcanic heat warming trapped ground water.

Types of Volcanoes

Fissure Volcano

• Fissure volcanoes are hard to recognize. • There is no central crater at all! Instead, giant

cracks open in the ground and spew out large amounts of lava that spread out and can cover almost everything in the area. – After the lava cools, the surface is mostly flat. The

cracks where the lava erupted are hidden, and that is why it is difficult to recognize this type of volcano.

*Los Pilas volcano in Nicaragua is an example of this type of volcano. Today fissure volcanoes are best seen in Iceland.

Shield Volcanoes

• Shield volcanoes have low slopes and are made almost entirely of frozen lava.

• They usually have large craters at the top. • This type of volcano can be hundreds of miles

across and many tens of thousands of feet high.*The individual islands of Hawaii are large shield volcanoes. *Mauna Loa is also the largest single mountain in the world, over 30,000 feet tall, and almost 100 miles across. *Other shield volcanoes can be found on the Galapagos Islands and on Iceland

Dome Volcanoes

– Acid lava is much thicker than lava which flows from shield volcanoes.

– Dome volcanoes have much steeper sides than shield volcanoes. This is because the lava is thick and sticky. It cannot flow very far before ot cools and hardens.

*An example is Puy de Dome in the Auvergne region of France which last erupted over 1 million years ago.

Ash-Cinder

• Cinder cones are the simplest type of volcano. • These volcanoes are mostly made up of loose, grainy

cinders and almost no lava. • They are small volcanoes, only about a mile across and

up to about a thousand feet high. They have very steep sides and usually have a small crater on top.

• Cinder cone volcanoes are often found on the sides of shield volcanoes. *There are over 100 cinder cone volcanoes on Mauna Kea, a shield volcano on Hawaii. Cerro Nego in Nicaragua is the most active cinder cone. It last erupted in 1995.

Composite

– Composite volcanoes are the most beautiful and the most deadly!

– These volcanoes can be tens of miles across and ten thousand feet in height.

– They have moderately steep sides and sometimes have small craters at the top.

– They have layers of lava mixed with layers of sand or volcanic rock called cinders.

*Some famous composite volcanoes are Krakatoa, Vesuvious, Fujiyama, Mount Rainier and Mount St. Helens. Krakatoa, in Indonesia, erupted in 1883 and made the loudest sound ever heard by human beings! ****This volcano is still active.

Bibliography

• http://mediatheek.thinkquest.nl/~ll125/images/volcano.jpg

• http://www.dembsky.net/volcano/

• http://volcano.und.edu/

• http://en.wikipedia.org/wiki/Volcano

• http://www.geology.sdsu.edu/how_volcanoes_work/

Caldera Volcanoes

• Calderas are circular depressions, found on the tops of many volcanoes.

• They can be difficult to recognize. • The huge craters can be many tens of miles across. • They form in gigantic eruptions that spew volcanic rocks

out up to a thousand miles in all directions. • The huge amount of magma that is spewed out leaves

behind a large crater. That is how a caldera is formed.*There is a caldera that nearly covers Yellowstone National

Park. It is so filled with lava and ash that you can hardly see the depression at all! Valles Caldera in New Mexico is another example of this type of volcano.