Q:

How do earthquakes occur?

A:

Quick Answer

Earthquakes occur when two blocks of earth suddenly slip past each other. This sudden release of energy causes the seismic waves that make the ground shake. The surface where they slip is known as the fault or fault plane.

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How do earthquakes occur?
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Full Answer

According to Universe Today, earthquakes occur as a result of tectonic plates colliding and volcanic eruption. To be considered an earthquake, a shock wave has to be of natural origin. Earthquakes occur when rock underground suddenly breaks along a fault. The spot underground where the rocks break is the focus of the earthquake. The place directly above the focus on top of the ground is the epicenter of the earthquake.

Major earthquakes are often preceded by more frequent minor shocks, known as foreshocks, as the rocks begin to move. Following the main shock, further movements, known as aftershocks, occur as the rock masses settle in their new positions. Aftershocks cause problems for rescue services because they can bring down buildings that were weakened by the primary earthquake.

Earthquake-like seismic waves can also be caused by explosions underground. These explosions are triggered in order to break rock while making tunnels for roads, railroads, subways or mines. These manmade explosions, however, don't cause very strong seismic waves.

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Related Questions

  • Q:

    Where do earthquakes occur most often?

    A:

    Earthquakes occur most often along the edges of oceanic and continental plates. Oceanic plates are the large pieces of the Earth's crust that are located beneath the oceans. Continental plates hold the Earth's large land masses.

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  • Q:

    How many earthquakes occur each year?

    A:

    According to the United States Geological Survey, several million earthquakes occur worldwide each year. It is difficult to refine this estimation to an exact number because many earthquakes go undetected, either because they occur in locations that are uninhabited or barely inhabited, or they are too small in magnitude to be detected by seismographs or other forms of detection.

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  • Q:

    Why do earthquakes occur in California?

    A:

    California has a relatively high number of earthquakes due to its position on both the Pacific and North American Plates. These plates are in constant motion, and earthquakes occur when their sides slip against one another suddenly.

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  • Q:

    How many earthquakes occur every year?

    A:

    As of 2014, estimates suggest that over 500,000 earthquakes occur each year, and 100,000 of these are strong enough to be felt by humans. Since 1900, there has been a global average of 18 major earthquakes, and one giant earthquake, each year.

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