what is a earthquake?

Answer 1

Shifting of tectonic plates cause faultlines in the earths crust to move or open up and this causes the ground to shake violently...Earthquake.

Answer 2

.An earthquake is cause by the movement of tectonic plates that ride on the earth's magma below. There are two main ways plates may collide. The first is laterally. This involves the plates 'sliding' past each other. At times they snag and as they continue to move an enormous amount of tension is built up until the rock fails, releasing the plates with a jolt. Now you have your earthquake. The fault line in such a situation where two plates are moving along one another laterally is called a STRIKE-SLIP fault. Examples of this are the San Andreas and Howard fault lines in California.

The second common fault line is called a subduction fault. This occurs when two tectonic plates have a head on collision, and one plate slides under the other. This also causes earthquakes, but is different from the strike-slip fault in that it also causes volcanoes due to the huge amount of heat from the friction of this 'collision'. The Pacific (ocean) Ring of Fire is called that due to subduction of the plates and the underwater volcanoes (ie Hawaii) and on land volcanoes (ie Mount Fuji, Japan) that are created.

Answer 3

All recorded earthquakes in British Columbia and in the offshore have occurred either within the Juan de Fuca or the North American plates. None have occurred along the junction where the two plates are actually in contact. Thus most recorded earthquakes represent the response of bedrock to stress accumulation within the plates.

The apparent inactivity within the zone of contact between the Juan de Fuca and North American plates suggests that either the two plates are locked together and are accumulating strain or that the contact zone is well lubricated and the plates are moving smoothly past each other. Stress accumulation that may occur between two locked plates can result in a potentially very destructive type of earthquake, called a megathrust earthquake.

Although no megathrust earthquakes have occurred in B.C.'s recorded history, scientific evidence is accumulating in favour of this possibility

Answer 4

The natural movement (due to the pressure of magma that comes up from the inner core) between plates in the earth is called an EARTHQUAKE. If it happens ins land its called an Earthquake and if it is happen in ocean its called Tsunami

Answer 5

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 tsunamis, which may lead to loss of life and destruction of property.

Earthquakes may occur naturally or as a result of human activities. In its most generic sense, the word earthquake is used to describe any seismic event—whether a natural phenomenon or an event caused by humans—that generates seismic waves.

Naturally occurring earthquakes
Most naturally occurring earthquakes are related to the tectonic nature of the Earth. Such earthquakes are called tectonic earthquakes. The Earth's lithosphere is a patchwork of plates in slow but constant motion caused by the heat in the Earth's mantle and Planetary core. Plate boundaries grind past each other, creating frictional stress. When the frictional stress exceeds a critical value, called local strength, a sudden failure occurs. The boundary of tectonic plates along which failure occurs is called the fault plane. When the failure at the fault plane results in a violent displacement of the Earth's crust, the elastic strain energy is released and seismic waves are radiated, thus causing an earthquake. This process of strain, stress, and failure is referred to as the Elastic-rebound theory. It is estimated that only 10 percent or less of an earthquake's total energy is radiated as seismic energy. Most of the earthquake's energy is used to power the earthquake fracture growth and is converted into heat. Therefore, earthquakes lower the Earth's available potential energy, though these losses are negligible.[1]

Earthquakes occurring at boundaries of tectonic plates are called interplate earthquakes, while the less frequent events that occur in the interior of the lithospheric plates are called intraplate earthquakes.

The majority of tectonic earthquakes originate at depths not exceeding a few tens of kilometers. In subduction zones, where older and colder oceanic crust descends beneath another tectonic plate, earthquakes may occur at much greater depths (up to hundreds of kilometers). These seismically active areas of subduction are known as Wadati-Benioff zones. Deep focus earthquakes are another phenomenon associated with a subducting slab. These are earthquakes that occur at a depth at which the subducted lithosphere should no longer be brittle, due to the high temperature and pressure. A possible mechanism for the generation of deep focus earthquakes is faulting caused by olivine undergoing a phase transition into a spinel structure.[2]

Earthquakes may also occur in volcanic regions and are caused by the movement of magma in volcanoes. Such quakes can be an early warning of volcanic eruptions.

A recently proposed theory suggests that some earthquakes may occur in a sort of earthquake storm, where one earthquake will trigger a series of earthquakes each triggered by the previous shifts on the fault lines, similar to aftershocks, but occurring years later, and with some of the later earthquakes as damaging as the early ones. Such a pattern was observed in the sequence of about a dozen earthquakes that struck the North Anatolian Fault in Turkey in the 20th Century, the half dozen large earthquakes in New Madrid in 1811-1812, and has been inferred for older anomalous clusters of large earthquakes in the Middle East and in the Mojave Desert.

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Answer 6

an earthquake is a suddent movement of the earth due to the tectonic plaques influenced by the magma currents. is say sudden because the tectonic plaques moves constantly but not fast. if he movement is on the land is called earthquake if is under water is called EARTHQUAKE but generates high waves called tsunami. the center of an earthquake is called epicentre (epicentrum). there is a scale that measures the intensity of it (richter) and another one mercalli.