Volcanoes and Their Characteristics

This set of flashcards covers key vocabulary and concepts related to volcanoes, including types of magma, eruption characteristics, and specific volcanic features.

Volcano

A geological structure that forms when magma from beneath the Earth's crust escapes to the surface.

Magma

Molten rock located beneath the Earth’s surface.

Lava

Magma that has reached the Earth's surface.

Felsic

Magma that is high in silica, typically resulting in a higher viscosity.

Mafic

Magma that is lower in silica, resulting in lower viscosity.

Viscosity

A measure of a fluid's resistance to flow. High viscosity means it flows less easily.

Basalt

A dark, fine-grained volcanic rock that is typically formed from mafic magma.

Pyroclastic Rocks

Volcanic rock fragments ejected during an explosive eruption.

Eruption

The process by which magma is expelled from a volcano.

Explosive Eruption

An eruption that is characterized by violent outbursts including ash, gas, and lava.

Effusive Eruption

An eruption characterized by the flow of lava out of a volcano.

Crater

The bowl-shaped depression at the top of a volcano formed by eruptions.

Vent

The opening in a volcano through which lava, gases, and ash are expelled.

Hotspot

A location where magma rises to the surface, often not associated with tectonic plate boundaries.

Dome Volcano

A volcano that is formed from viscous lava that doesn't flow far, creating a steep-sided structure.

Lava Flow

The movement of lava as it exits a volcano.

Venting

The release of gas from a volcano, which can affect its explosiveness.

Volcanology

The study of volcanoes, lava, magma, and related phenomena.

Tephra

Any fragments of volcanic rock or ash that are ejected during an eruption.

Ash Cloud

A cloud of ash particles that are released into the atmosphere during an explosive volcanic eruption.

Fountain

The eruption of lava that is propelled into the air in a fountaining manner.

Lahar

A destructive volcanic mudflow that results from mixing volcanic ash and debris with water.

Volcanic Gas

Gases released during a volcanic eruption, which can include water vapor, carbon dioxide, and sulfur dioxide.

Debris Flow

A rapid flow of sediment mixed with water, potentially triggered by volcanic eruptions.

Magmatic Gas

Gas trapped in magma that influences the pressure conditions under which magma rises.

Convergent Boundary

A tectonic plate boundary where two plates collide, often producing volcanic activity.

Divergent Boundary

A tectonic plate boundary where two plates move away from each other, commonly associated with volcanic activity.

Spirit Lake

A lake affected by the eruption of Mount St. Helens, which became notable for the trees blasted into it.

Mount St. Helens

A stratovolcano located in the Pacific Northwest of the USA, known for its catastrophic 1980 eruption.

Gaseous Dissolution

The process by which gases are dissolved in magma, relevant to eruption dynamics.

Seismic Activity

Earthquake activity associated with the movement of magma beneath the Earth's surface.

Magma Chamber

A large underground pool of molten rock located beneath the surface of the Earth.

Lava Tube

A natural conduit formed by flowing lava that moves beneath the surface of a lava flow.

Geological Hazard

A natural hazard that occurs because of geological processes, which includes volcanic eruptions.

Caldera

A large depression formed when a volcano erupts and collapses.

Volcanic Ash

Tiny rock and glass particles created during a volcanic eruption.

Volcanic Winter

A reduction in global temperatures caused by volcanic eruptions that release large amounts of ash into the atmosphere.

Fissure Eruption

A type of volcanic eruption where magma escapes from a linear crack.

Igneous Rock

Rock that forms when magma cools and solidifies.

Aphanitic

A texture of igneous rock where the crystals are too small to be seen with the naked eye.

Phaneritic

A texture of igneous rock where the crystals are large enough to be seen.

Tephra Fall

Deposits of volcanic material that settle to the ground after being ejected into the air during an eruption.

Sill

A horizontal sheet of igneous rock formed by the intrusion of magma between rock layers.

Lava Plateau

A flat, elevated region formed by the eruption of low-viscosity lava that flows over long distances.

Andesitic Magma

Intermediate volcano magma composition which has moderate viscosity and explosiveness.