Volcanoes

Volcanoes are classified in one of three ways.

If they can erupt at any time (or have erupted in the past 50 years) they are considered as _____. active.

If they have not erupted in the past 50 years but still might they are classified as ________ dormant.

If they will never erupt again they are classified as ______. extinct.

Some famous volcanoes include 1)Pinatubo - (1991, Philippines) largest 20th century

Some famous volcanoes include: 2)Kilauea - (Hawaii) erupting for centuries

Some famous volcanoes include: 3)Mt. St. Helen - (1980, Washington) most recent eruption in continental United States

Some famous volcanoes include: 4)Krakatoa - (1883 near Java) one of the largest in recorded history, 36,000 killed in tsunami.

Some famous volcanoes include: 5) Paracutin - (1943, Mexico) cone grew almost overnight

Some famous volcanoes include: 6) Mt. Rainier - (near Seattle, Washington) could be most dangerous volcano in United States

Some famous volcanoes include: 7) Mt. Hood - (near Portland, Oregon) also could threaten populated area in United

Mt. St. Helen, Mt. Rainier, & Mt. Hood are located in the _________ Mountains of Washington, Oregon, California Cascade

Volcanoes of the Cascade Mountains

Most active volcanoes are located around the ___________ Pacific Ring of Fire.

Volcanoes form under three geologic conditions. They are:

1) Subduction zones at convergent plate boundaries

Suduction Zone

An example of a subduction zone volcano is ______. Mount. St. Helen.

Diagram of subduction zone volcano

2) Divergent plate boundaries

An example of a divergent ocean boundary volcano is ______. Iceland.

Diagram of divergent ocean boundary volcano

Rift Valley

An example of a divergent continental boundary volcano is ______. Mt. Kilimanjaro, African Rift Valley.

Diagram of divergent continental boundary volcano

3) Hot spots

It is believed that hot spots were responsible for _______. breaking apart Pangaea

Hot Spot

A B

The intensity of a volcanic eruption is determined by ____, _____, and _____. magma type, amount of water in magma, amount of gas.

Two magma types are ___ and ___. granite (solidified magma of this type makes up the continents – this makes a very explosive magma) basalt (solidified magma of this type makes up ocean floor-this usually makes a non explosive magma)

When these two magma types mix, a third type of magma is formed. This is called _____ magma. andesite

Andesite magma is explosive when it contains sufficient _____ and _____. water trapped gasses.

Material from a volcanic eruption includes ____, ____, and ____. lava, tephra (cinders and small rock fragments), pyroclastic material (this means “fire rock”

The material that kills the most people in an eruption is _______. pyroclastic.

Volcanic eruptions both _____ ____ and _____ the volcanic “cone”. build destroy

The cone is build up during quiet eruptions and destroyed (“blown apart”) during violent eruptions.

The are three basic shapes of volcanic cone. They are ___, ___, and ___. shield cone, cinder cone, composite cone (also called strato).

Shield cone volcanoes are made from ______. These volcanoes are usually made from ____ lava, and are non-explosive. lava flows basalt

These volcanoes are ____ and have _____. broad gently sloping sides.

______ in Hawaii is an example of a shield cone volcano. Kilauea

Cinder cone volcanoes are made from ______. These volcanoes are usually made from ____ lava, and are explosive. tephra granite

These volcanoes are ____ and have _____. small steep sides.

______ in Mexico is an example of a cinder cone volcano. Paracutin

Composite cone volcanoes are made from ______. These volcanoes are usually made from ____ lava, and are can be either explosive or non-explosive. lava/tephra eruptions andesite

These volcanoes are ____ and have _____. steep on top flat base

______ in Washington is an example of a composite cone volcano. Mt. St Helen

Volcanic features include _____,_____, and _____. volcanic necks, batholiths, calderas.

A _____ is an _______ of an extinct volcano volcanic neck erosional remnant

_____ (in Wyoming) is an example of this feature. Devils Tower

Intrusive Igneous Features

A _____ is the exposed ______. batholith magma chamber.

A ____ is a _______. caldera collapsed volcano

Formation of Crater Lake