The basement is the harder and usually older layer of igneous and metamorphic rocks that underlie the main sedimentary rock sequences (softer and usually younger) of a region and extend downward to the base of the crust.

Bedrock
The bedrock is the relatively hard, solid rock that commonly underlies softer rock, sediment, or soil; a subset of the basement.

A dipping planar (flat) zone of earthquakes that is produced by the interaction of a downgoing oceanic crustal plate with a continental plate. These earthquakes can be produced by slip along the subduction thrust fault or by slip on faults within the downgoing plate as a result of bending and extension as the plate is pulled into the mantle. Also known as the Wadati-Benioff zone.

A blind thrust fault is a thrust fault that does not rupture all the way up to the surface so there is no evidence of it on the ground. It is "buried" under the uppermost layers of rock in the crust.

A body wave is a seismic wave that moves through the interior of the earth, as opposed to surface waves that travel near the earth's surface. P and S waves are body waves. Each type of wave shakes the ground in different ways.

P wave
A P wave, or compressional wave, is a seismic body wave that shakes the ground back and forth in the same direction and the opposite direction as the direction the wave is moving.

S wave
An S wave, or shear wave, is a seismic body wave that shakes the ground back and forth perpendicular to the direction the wave is moving.

The brittle-ductile boundary is the depth in the crust where the crust changes from being brittle (tending to break) above, to being ductile (tending to bend) below. This coincides with the boundary between the lithosphere and the asthenosphere. Most earthquakes occur in the brittle portion of the crust above the brittle-ductile boundary.