The World of Volcanoes Mrs. Lozano. What is a volcano? A mountain formed by lava and ash.

The World of Volcanoes

Mrs. Lozano

What is a volcano?

• A mountain formed by lava and ash

What is Lava?• Lava is magma that reaches

Earth’s surface

• Okay...I know what lava is, but what exactly is Magma?

• Magma is hot, soft rock from Earth’s mantle.

What is ash?• Ash is small pieces of hardened

lava

• Savage Earth Animation

How do volcanoes form?• Continental plates and oceanic

plates collide• Subduction occurs• Melted rock becomes magma that

forces its way up between the plates

• Savage Earth Animation #2

How do volcanoes form?

Continental Drift

• Continental Drift Animation

Where are these “Subduction Zones?”

• Many volcanoes are located at plate boundaries around the Pacific plate.

• The Pacific plate is often called the “Ring of Fire”

Do all volcanoes look the same?• No, there are many different kinds

of volcanoes such as:• Shield Volcanoes that can be

found in Hawaii

• Cinder Cone Volcanoes can be found in Costa Rica

• Composite Volcanoes like Mt. Saint Helen

• And Fissure Volcanoes found in Nicaragua .

Do subduction zones create all volcanoes?• No, volcanoes can also be formed

by Hot Spots.• Hot Spots are volcanic areas on

the surface of the Earth that are created by a rising plume of magma.

• http://www.classzone.com/books/earth_science/terc/content/investigations/es0810/es0810page03.cfm

Volcanic Hazards • Volcanoes can create landslides

that bury land, homes and sometimes people.

Volcanic Hazards• Volcanoes can create Earthquakes

that may produce hazards which include ground cracks, ground deformation, and damage to manmade structures.

Volcanic Hazards• Pyroclastic Surge that spews

extremely hot ash that races down the mountain and swallows everything in its path.

Volcanic Hazards• Lava flows are the most famous

yet the least dangerous of hazards.

Volcanic Hazards• There are two kinds of lava flows:

– Pahoehoe

– `A`A

I love Volcanoes!!!!!!• Although volcanoes are beautiful

and wondrous things, they can be harmful and cause many disasters. It is better to love volcanoes from a far off distance.