Volcanoes: Basic Information

A vocabulary set covering the key terminology, definitions, and notable examples from the basic volcano lecture notes.

Volcano

An opening in the Earth's crust where magma escapes.

Magma

Molten rock while it is underground.

Lava

Molten rock once it reaches the surface.

Crater

The opening at the top of a volcano.

Conduit

The underground tube that magma travels up through (also known as a vent).

Tephra

Rock fragments thrown out during an eruption (also known as pyroclastic material).

Ash

Fine, powdery volcanic material.

Active Volcano

A volcano that is currently erupting or expected to erupt again.

Dormant Volcano

A volcano that has not erupted in a long time but could again.

Extinct Volcano

A volcano no longer expected to erupt.

Composite Volcano (Stratovolcano)

A tall, steep-sided volcano built from alternating lava and ash layers.

Shield Volcano

A broad and gently sloped volcano formed from runny lava.

Cinder Cone

A small, steep volcano made of loose volcanic debris.

Caldera

A large, bowl-shaped depression that forms after a volcano collapses.

Ring of Fire

The boundary along the Pacific Ocean with many volcanoes and earthquakes.

Felsic Lava

Thick, slow-flowing (viscous) lava.

Mafic Lava

Thin, fast-flowing (runny) lava.

Sulfur Dioxide

A gas commonly released during eruptions that can affect climate (carbon dioxide is also released).

Pyroclastic Flow

A fast-moving current of hot gas and ash.

Hotspot

A spot where magma rises far from a plate boundary.

Kilauea

A Hawaiian volcano that is an example of a hotspot volcano (Mauna Loa is also an example).

Mount St. Helens

A Washington State volcano that famously erupted in 1980.

Mount Vesuvius

An Italian volcano that destroyed Pompeii in 79 AD.

Pompeii

An ancient Roman city buried by Mount Vesuvius's eruption.

Convergent Boundary

A type of plate boundary (or subduction zone) that often forms volcanoes as one plate sinks beneath another.

Igneous Rock

Magma or lava that has cooled and hardened into rock.

Volcanologist

A scientist who studies volcanoes.

Earthquakes

A natural warning sign (tremors) that often precedes a volcanic eruption.

Eruption

The process of a volcano releasing lava, ash, and gas.

Krakatoa

An Indonesian volcano whose 1883 eruption was one of the loudest sounds in recorded history.