Volcano Vocabulary

A weak spot in the crust where magma has come to the surface.

The molten mixture of rock-forming substances, gases, and water from the mantle.

Liquid magma that reaches the surface; also the rock formed when liquid lava hardens.

A major belt of volcanoes that rims the Pacific Ocean.

A string of islands formed by the volcanoes along a deep-ocean trench.

An area where magma from deep within the mantle melts through the crust above it.

A substance that cannot be broken down into other substances.

A substance in which two or more elements are chemically joined.

Any characteristic of a substance that can be observed or measured without changing the composition of the substance.

Any property of a substance that produces a change in the composition of matter.

The resistance of a liquid to flowing.

A material found in magma that is formed from the elements oxygen and silicon.

A hot, fast-moving type of lava that hardens to form smooth, ropelike coils.

A slow-moving type of lava that hardens to form rough chunks; cooler than pahoehoe.

The pocket beneath a volcano where magma collects.

A long tube through which magma moves from the magma chamber to Earth’s surface.

The opening through which molten rock and gas leave a volcano.

The area covered by lava as it pours out of a volcano’s vent.

A bowl-shaped area that forms around a volcano’s central opening.

The expulsion of ash, cinders, bombs, and gases during an explosive volcanic eruption.

A volcano that is not currently active, but may become active in the future.

A volcano that is no longer active and is unlikely to erupt again.

A wide, gently sloping mountain made of layers of lava and formed by quiet eruptions.

A steep, cone-shaped hill or small mountain made of volcanic ash, cinders, and bombs piled up around a volcano’s opening.

A tall cone-shaped mountain in which layers of lava alternate with layers of ash and other volcanic materials. aka stratovolcano

The large hole at the top of a volcano formed when the roof of a volcano’s magma chamber collapses.

A deposit of hardened magma in a volcano’s pipe.

A slab of volcanic rock formed when magma forces itself across rock layers.

A slab of volcanic rock formed when magma squeezes between layers of rock.

A mass of rock formed when a large body of magma cools inside the crust.

The heating of underground water by magma.

A fountain of water and steam that builds up pressure underground and erupts at regular intervals.