Glossary

A caldera is deep hole created when the top of a volcano blows off.  

A dome volcano is a rounded or dome-shaped volcano that grows slowly.  They usually form in the crater after the eruption of a bigger volcano or after an earthquake where two plates have separated.

The earth's crust is the outer layer of the earth.  The plates are part of earth's crust.

An eruption occurs when magma breaks through the crust with a lot of force causing rocks, steam, ash, and lava to burst into the air.  Some eruptions can be small, but some can be very big and violent creating a big change in the area around it. 

Extinct means no longer active.  An extinct volcano is a volcano that is not active and is not expected to erupt in the future.  This is often because the source of magma is not longer under the volcano.

Graph paper is paper that has lines that go across the paper and lines that go up and down on the paper.  It is usually used to record information in the form of a graph.

A hot spot is an area where the crust is thin and magma is pushing up very close to the surface.  The magma may break through and create a hot spot volcano.

Japan is a country in Asia.  It is an island that is on the Pacific Rim and has volcanoes and earthquakes.

Lava is molten rock (magma) that comes out of a volcano.

Magma is molten rock that is beneath the earth's crust.

A plate is a massive slab of rock that floats on the mantle and is part of the earth's crust.  There are many plates that make up the earth's crust.  These plates are also called tectonic plates.

A subduction zone is the area where one plate slides under another.  Volcanoes often occur along subduction zones.

A tsunami is a giant wave of water that is caused by an earthquake or the eruption of a volcano.  Tsunamis can cause a lot of destruction when they hit land.

Violent means physical force that hurts or damages something.  A violent volcano causes a lot of damage.