Types of Volcanoes and Their Characteristics

These flashcards cover key vocabulary and concepts related to volcano types, their characteristics, and associated hazards.

Mafic volcanoes

Volcanoes that are low in silica and high in iron, magnesium, and calcium, typically producing basalt.

Intermediate volcanoes

Volcanoes that have a moderate silica content, potentially leading to explosive eruptions.

Felsic volcanoes

Volcanoes rich in silica, typically producing lighter-colored lava like rhyolite, and known for their explosive eruptions.

Silica

A chemical compound (SiO2) that is a primary component of most igneous rocks, influencing magma viscosity.

Viscosity

A measure of a fluid's resistance to flow; lower viscosity means a more fluid lava.

Explosive magma

Magma that traps gas, leading to explosive volcanic eruptions.

Basalt

A dark, mafic igneous rock, commonly associated with volcanic activity.

Rhyolite

A light-colored, felsic igneous rock formed from high-silica magma.

Composite volcano

A tall, steep volcano built of alternating layers of lava flows, tephra, and ash.

Shield volcano

A broad, gently sloping volcano formed by the eruption of low-viscosity basaltic lava.

Cinder cone

A small, steep-sided volcano formed from tephra, typically erupting explosively.

Lahar

A volcanic mudflow that occurs when volcanic material mixes with water, often from melted snow or rainfall.

Tephra

Fragmented material produced by a volcanic eruption, which includes ash, pumice, and volcanic rock.

Pyroclastic flow

A fast-moving current of hot gas and volcanic matter that flows down a volcanic eruption.

Fissure eruption

A volcanic eruption that occurs from a crack rather than a central vent.

Volcanic dome

A dome-shaped protrusion formed from the slow extrusion of high-viscosity lava.

Volcanic gases

Gaseous emissions from a volcano, including water vapor, carbon dioxide, sulfur dioxide, and more.

Volcanic ash

Fine particles of rock and glass formed during explosive volcanic eruptions.

Hazard associated with volcanoes

Various dangers posed by volcanic activity, including lava flows, ash falls, and toxic gases.

Magma composition

The chemical and mineralogical makeup of magma, influencing volcanic behavior.

Hawaiian eruption

A type of volcanic eruption characterized by low-viscosity lava flows, typically from shield volcanoes.

Subduction zone

An area where one tectonic plate moves under another, often leading to volcanic activity.

Hotspot

An area where molten material from the mantle reaches the crust, causing volcanism, i.e., Hawaii.

Flood events

Volcanic-related floods resulting from the melting of glaciers or heavy rainfall on volcanic deposits.

Viscosity and gas content relationship

Higher gas content and viscosity in lava typically lead to more explosive volcanic eruptions.

Granite

A common igneous rock that is typically coarse-grained and forms from slow-cooling magma.

Diorite

An intrusive igneous rock composed of intermediate minerals, often exhibiting a salt-and-pepper appearance.

Gabbro

A coarse-grained igneous rock formed from mafic magma, similar in composition to basalt.

Explosive eruptions

Eruptions marked by violent expulsion of material due to high gas pressure in magma.

Mount St. Helens

A composite volcano in Washington known for its significant eruption on May 18, 1980.

Mount Rainier

A prominent composite volcano in Washington that poses significant volcanic risk.

Mount Fuji

An iconic composite volcano in Japan, known for its symmetrical cone shape.

Iceland

An island associated with both hotspot and divergent plate boundary volcanism.

Volcanic monitoring

The science of observing and predicting volcanic eruptions to mitigate hazards.

Eruption column

A vertical plume of gas, ash, and volcanic matter released during an explosive volcanic eruption.

Volcano alert levels

A system used by volcano observatories to communicate the level of volcanic activity and hazard.

Sulfide mineral deposits

Minerals such as sulfur that form from volcanic gases and can indicate past volcanic activity.

Earthquake and volcanic activity correlation

Seismic activity often precedes volcanic eruptions, helping to monitor and predict eruptions.

Short-lived volcanoes

Volcanoes that erupt briefly before becoming dormant, such as many cinder cones.

Dome collapse

The event where a volcanic dome becomes unstable and collapses often leading to explosive activity.