Quake (natural phenomenon)

A quake is the result when the surface of a planet, moon or star begins to shake.

Types of quakes include:

Earthquake

See also: Earthquake

An earthquake is a phenomenon that results from the sudden release of stored energy in the Earth's crust that creates seismic waves. At the Earth's surface, earthquakes may manifest themselves by a shaking or displacement of the ground and sometimes cause tsunamis, which may lead to loss of life and destruction of property. An earthquake is caused by tectonic plates (sections of the Earth's crust) getting stuck and putting a strain on the ground. The strain becomes so great that rocks give way and fault lines occur.

Moonquake

A moonquake is the lunar equivalent of an earthquake (i.e., a quake on the Moon). They were first discovered by the Apollo astronauts. Moonquakes are much weaker than earthquakes.

Information about moonquakes comes from seismometers placed on the Moon by Apollo astronauts from 1969 through 1972. The instruments placed by the Apollo 12, 14, 15 and 16 functioned perfectly until they were switched off in 1977.

According to NASA, there are at least four different kinds of moonquakes:

• Deep moonquakes (~700 km below the surface, probably tidal in origin)
• Meteorite impact vibrations
• Thermal moonquakes (the frigid lunar crust expands when sunlight returns after the two week lunar night)
• Shallow moonquakes (20 or 30 kilometers below the surface)

The first three kinds of moonquakes mentioned above tend to be mild; however, shallow moonquakes can register up to 5.5 on the Richter scale. Between 1972 and 1977, twenty-eight shallow moonquakes were observed. On Earth, quakes of magnitude 4.5 and above can cause damage to buildings and other rigid structures.

Marsquake

A marsquake is a quake that occurs on the planet Mars. There is currently no explanation as to why marsquakes occur. Marsquakes occur because of movement of the plates.

Venusquake

A venusquake is a quake that occurs on the planet Venus.

A venusquake may have caused a new scarp and a landslide to form. An image of the landslides was taken in November 1990 during the first flight around Venus by the Magellan's spacecraft. Another image was taken on July 23, 1991 as the Magellan spacecraft revolved around Venus for the second time. Each image was twenty-four kilometers (14.4 miles) across and thirty-eight kilometers (twenty-three miles) long, and was centered at two degrees south latitude and seventy-four degrees east longitude. The pair of Magellan images shows a region in Aphrodite Terra, within a steeply sloping valley that is cut by many fractures (Faults).

Planetquake

Planetquake is the generic term for quakes occurring on terrestrial planets.

Sunquake

A sunquake is a quake that occurs on the Sun.

Seismic waves produced by sunquakes can shake the Sun to its very center, just as earthquakes can cause the entire Earth to shake. However, sunquakes involve much more energy than their terrestrial counterparts. An observed sunquake, which was produced by a perfectly ordinary solar flare, was equivalent to an earthquake of a magnitude 11.3 on the Richter scale. That is 89,000 times more energy than the devastating 1906 San Francisco earthquake, at a magnitude of 8 on the same scale. Scientists remain somewhat perplexed about how such a relatively modest flare could have the downward thrust and power to generate such powerful seismic waves.

Starquake

A starquake is an astrophysical phenomenon that occurs when the crust of a neutron star undergoes a sudden adjustment, analogous to an earthquake on Earth. This is thought to be the source of the giant gamma ray flares that are produced approximately once per decade from soft gamma repeaters. Starquakes are thought to be caused by huge stresses exerted on the surface of the neutron star produced by twists in the ultra-strong interior magnetic fields.

The largest recorded starquake occurred on the ultracompact stellar corpse (magnetar) SGR 1806-20. It released gamma rays equivalent to 10³⁶ kW in intensity. This starquake occurred 50,000 light years away. Had the event occurred within a distance of ten light years from Earth, the event could have potentially triggered a mass extinction on Earth.

See also

• Magnetar
• Neutron star
• Pulsar
• Soft gamma repeater