Earthquake 1

Earthquake

A vibration of the Earth produced by the rapid release of energy.

Focus

The source at depth from which energy radiates as seismic waves in all directions; site of initial rupture.

Epicenter

The surface location above the source (focus) of an earthquake.

Seismic waves

Elastic energy that radiates in all directions from the focus of an earthquake.

Elastic Rebound

The process that causes earthquakes, involving the storage of elastic energy and its sudden release.

Fault creep

Gradual fault movement that releases elastic energy so little is stored; results in small earthquakes.

Stick-slip fault

A fault that locks and stores elastic energy for long periods; its release produces large, dangerous earthquakes.

Fault scarp

A cliff produced by vertical offset along a fault.

Foreshocks

Small earthquakes that occur days to years before a major earthquake.

Aftershocks

Smaller earthquakes that occur for days after the main earthquake.

Rate of Movement

The measure of fault movement listed as movement per year, regardless of the frequency of actual movement.

Elastic energy

The potential energy stored in a material that can be released when the material returns to its original shape.

Volcanic eruption

A trigger for earthquakes caused by the release of magma, gases, or pyroclastic material.

Nuclear blast

An artificial trigger for earthquakes caused by the detonation of a nuclear weapon.

Strain release

The process by which accumulated elastic energy is released during an earthquake.

Vertical offset

Movement along a fault that produces a noticeable vertical displacement on the surface.

Horizontal offset

Movement along a fault that produces lateral displacement of structures without vertical displacement.

Fault

A crack in the Earth's crust along which movement has occurred.

Tectonic forces

Forces generated by the motion of the Earth's tectonic plates, often causing rock deformation.

Seismic activity

The frequency, type, and size of earthquakes experienced over a period of time in a specific area.

Monitoring earthquakes

The observation and analysis of seismic activity to predict potential earthquake events.

Elastic limit

The maximum extent to which a material can be deformed and still return to its original shape.

Seismic hazard

The risk associated with earthquakes, considering potential damage and casualties.

Cycle of earthquakes

The repeating process of elastic rebound and fault movement until the next earthquake occurs.

Energy release

The sudden liberation of stored energy during an earthquake, resulting in seismic waves.

Deep faults

Faults that do not express surface displacement, typically because they are located deep underground.

Earthquake duration

The length of time an earthquake lasts, typically from seconds to minutes.

San Andreas Fault

A major fault line in California known for its significant seismic activity and movement of about 3 cm per year.