Benioff zone:

A narrow zone, defined by earthquake foci, that is tens of kilometers thick dipping from the surface under the Earth's crust to depths of up to 700 kilometers. (Also Wadati-Benioff zone.)

Blind thrust:

A deep crustal thrust-fault with no or only indirect surface expression such as a fold structure.

Body wave:

A seismic wave that can travel through the interior of the earth. P-waves and S-waves are body waves.

Body-wave magnitude:

Magnitude of an earthquake as estimated from the amplitude of body waves.

Capable fault:

A fault along which it is mechanically feasible for sudden slip to occur.

Characteristic earthquake:

An earthquake with a size and generating mechanism typical for a particular fault source.

Coda:

The concluding train of seismic waves that follows the principal waves from an earthquake.

Consolidated:

Tightly packed. Composed of particles that are not easily separated.

Continental Drift:

The theory, first advanced by Alfred Wegener, that Earth's continents were originally one land mass. Pieces of the land mass split off and migrated to form the continents.

Continental shelf:

Part of the continental margin between the coast and the continental slope.

Core:

The innermost layers of the Earth. The inner core is solid and has a radius of about 1300 kilometres. (The radius of the Earth is about 6371 kilometres.) The outer core is fluid and is about 2300 kilometres thick. S-waves cannot travel through the outer core.

Crust:

See Earth's Crust.