Natural Disasters: Volcanoes

This set of vocabulary flashcards covers the fundamental concepts of volcanology, including types of volcanoes, eruption styles, lava composition, and geothermal features based on the lecture notes.

Volcano

A weak spot in the crust where molten material, or magma, comes to the surface.

Magma

Molten material under the Earth’s surface.

Lava

Molten material above the Earth’s surface.

Ring of Fire

A major belt of volcanoes that rims the Pacific Ocean.

Magma chamber

A pocket beneath a volcano where magma collects.

Hot Spots

An area where material from deep within the mantle rises and then melts, forming magma; the volcano forms above it as magma erupts through the crust.

Viscosity

A measure of a fluid’s resistance to flow, which determines how easily a liquid flows.

Silica ($SiO_2$)

One of the two main factors, along with temperature, that determines the viscosity of magma.

Mafic Lava

Lava that is dark in color with low silica content, is less viscous, and results in quiet eruptions.

Felsic Lava

Lava that is light in color with high silica content, is very viscous, and results in explosive eruptions.

Quiet Eruptions

Volcanic eruptions that produce lava flows.

Explosive Eruptions

Volcanic eruptions that produce pyroclastic flows, lava bombs, and volcanic ash.

Shield Volcano

A volcano with wide, gentle slopes (typically 20 times wider than high) formed by low-viscosity lava at divergent plate boundaries, such as the Hawaiian Islands.

Composite Volcano (Stratovolcano)

A steep, cone-shaped towering structure rising more than $10,000 \, \text{ft}$, created by alternating layers of viscous lava and ash at convergent plate boundaries.

Cinder Cone

A small, steep, cone-shaped volcano (rarely exceeding $1,000 \, \text{ft}$) that produces ash, cinders, and bombs through explosive eruptions.

Calderas

Huge holes left by the collapse of a volcanic mountain, formed when magma is erupted and the mountain collapses inward.

Fissures

A fracture or crack in rock where there is distinct separation and lava erupts.

Active (Live) Volcano

A volcano that is erupting or has shown signs that it may erupt in the near future.

Dormant (Sleeping) Volcano

A volcano that does not show signs of erupting in the near future, but stay has the possibility to erupt.

Extinct (Dead) Volcano

A volcano that is unlikely to erupt again.

Geothermal Activity

A renewable type of energy taken from Earth’s core where magma beneath the surface heats underground water.

Geysers

Features formed when rising hot water and steam become trapped in a narrow crack, building pressure until the mixture sprays above the surface.

Hot Springs

Formed when magma or rock heated by magma underground rises to the surface and collects in a natural pool.