Volcanoes and Earthquakes - Key Terms

Flashcards covering key vocabulary from the lecture transcript.

Crust

The surface of the planet, divided into tectonic plates.

Oceanic crust

Denser and heavier type of crust.

Continental crust

Less dense type of crust.

Magma

Molten rock.

Earthquake

A sudden and violent shaking of the ground, sometimes causing great destruction, as a result of movements within the earth's crust or volcanic action.

Volcanic eruption

A rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface.

Plate margin

Where tectonic plates meet.

Natural hazard

A natural event such as a flood, earthquake, or hurricane that causes great damage or loss of life.

Plate tectonics

The theory that Earth's outer shell is divided into several plates that glide over the mantle, the rocky inner layer above the core.

Destructive margin

A margin where an oceanic plate moves towards a continental plate; the denser oceanic plate is subducted beneath the continental plate.

Conservative margin

A margin where two plates slide past each other; pressure builds up and is released as an earthquake when the plates suddenly jolt free.

Constructive margin

A margin where two plates move apart from each other; magma from the mantle rises to fill this gap and a volcanic eruption occurs.

Shield volcano

A broad, domed volcano with gently sloping sides, characteristic of the eruption of fluid, basaltic lava.