Ground motion is the movement of the earth's surface from

earthquakes An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in intensity, from ...

or explosions. Ground motion is produced by

seismic wave A seismic wave is a wave of acoustic energy that travels through the Earth. It can result from an earthquake, volcanic eruption, magma movement, a large landslide, and a large man-made explosion that produces low-frequency acoustic energy. S ...

s that are generated by sudden slip on a fault or sudden pressure at the explosive source and travel through the earth and along its surface. This can be due to natural events, such as

and

volcanic eruptions Several types of volcanic eruptions—during which lava, tephra (ash, lapilli, volcanic bombs and volcanic blocks), and assorted gases are expelled from a volcanic vent or fissure—have been distinguished by volcanologists. These are often ...

, or human activities, such as the detonation of

nuclear weapons A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission (fission bomb) or a combination of fission and fusion reactions (thermonuclear bomb), producing a nuclear explosion. Both bomb ...

. There are two main types of seismic waves: body waves and surface waves. Body waves travel through the interior of the earth, while surface waves travel along the earth's surface. Ground motion is typically caused by surface waves, which are the most destructive type of seismic waves. Ground motion is measured using a

seismometer A seismometer is an instrument that responds to ground noises and shaking such as caused by earthquakes, volcanic eruptions, and explosions. They are usually combined with a timing device and a recording device to form a seismograph. The outpu ...

, a device that detects and records the movement of the earth's surface. Seismometers are used by seismologists to study earthquakes and other types of ground motion. The recordings produced by a seismometer are known as seismograms, and they can be used to study the characteristics of the ground motion, such as its duration, amplitude, and frequency. Ground motion is typically measured in three components: west-to-east, south-to-north, and vertical. Recordings from multiple seismometers can be combined to form a detailed model of the ground motion. This is known as a seismograph, and it can be used to study the spatial and temporal characteristics of the ground motion. Seismographs can also be used to create maps of the ground motion, which can help scientists understand the distribution and intensity of the seismic waves.

References

{{Seismology-stub Seismology

See also

References