A measurable movement of the earth's crust. These release energy stored by the accumulation of stress along faults from tectonic activity.

Any force exerted on an object

A contact force that acts to squeeze or crush an object or substance.

Forces that act to pull an object apart. These forces act in line with each other.

Forces acting in opposite directions on different parts of the same object or substance. Opposing forces are not aligned so that matter within the object tends to slip in layers, like spreading a deck of cards.

upward force that a fluid exerts on an object in the fluid. The magnitude of the this force is equal to the weight of the displaced fluid.

The margin between two tectonic plates that are moving away from each other. These boundaries are the locations of sea-floor spreading and rift valleys.

The margin between two tectonic plates that are moving toward each other. these boundaries are often locations of subduction and mountain building.

The margin between two tectonic plates that are sliding in opposite directions parallel to the margin. These occur near faults that usually form across divergent boundaries in oceanic crust. On land, seismologists refer to them as strike-slip faults.

Any change in the shape of a solid due to stresses exerted on the material.

A crack in a rock that shows no indication of motion on either side of the crack. ____ in rock usually occur in groups and are related to the direction of the stress that formed them.

A joint or crack in rock where the rock on both sides of the crack has moved relative to each other. These may range in size from microscopic to many kilometers long.

The compass direction of the horizontal plane of the surface of a fault face or rock stratum.

The angle of slope of a fault face or stratum, measured from the horizontal plane.

A dip-slip fault in which the upper body of rock drops relative to the lower body of rock.

The first earthquake wave that reaches a seismic station from an earthquake. These are the fastest seismic waves. They pass through all parts of the earth's interior and tend to be the least destructive.

The second earthquake wave that reaches a seismic station from an earthquake.

A wave that occurs at the surface of the ocean, in comparison to an internal wave. These are formed by friction of wind blowing over the water.

The _______ is the location on the earth's surface directly above an earthquakes focus.

A scale that rates the magnitude of the intensity of an earthquake

The size or intensity of some measurable quantity. In seismology, it is a measure of an earthquakes energy. In astronomy, it is a measure of a stars brightness.

A measure of the concentration of energy or the effects of the energy released.

A far-reaching, devastating water wave caused by seismic activity.