Last Update: Jan 14, 2023.

Submitted by: Kristal Gerstein
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What cause an earthquake?

Earthquakes are the result of sudden movement along faults within the Earth. The movement releases stored-up 'elastic strain' energy in the form of seismic waves, which propagate through the Earth and cause the ground surface to shake.

Earthquake Magnitude ScaleMagnit�rthquake Effects5.5 to 6.0Slight damage to buildings and other structures.6.1 to 6.9May cause a lot of damage in very populated areas.7.0 to 7.9Major earthquake. Serious damage.8.0 or greaterGreat earthquake. Can totally destroy communities near the epicenter.

San Francisco General Hospital and Trauma Center Base isolation allows the building to withstand what structural engineers consider maximum earthquake-levels and remain elastic. The bearings used will even allow the building to re-center itself after an earthquake.

Magnitude is a measure of earthquake size and remains unchanged with distance from the earthquake. Intensity, however, describes the degree of shaking caused by an earthquake at a given place and decreases with distance from the earthquake epicentre.

Richter Scale

(That is, an earthquake measuring 5.0 releases 31 times more energy than an earthquake measuring 4.0.) In theory, the Richter scale has no upper limit, but, in practice, no earthquake has ever been registered on the scale above magnitude 8.6. (That was the Richter magnitude for the Chile earthquake of 1960.

Richter Scale

An earthquake is what happens when two blocks of the earth suddenly slip past one another. The surface where they slip is called the fault or fault plane.

Magnitude scales, like the moment magnitude, measure the size of the earthquake at its source. An earthquake has one magnitude. The magnitude does not depend on where the measurement is made. Often, several slightly different magnitudes are reported for an earthquake.

Magnitude scales, like the moment magnitude, measure the size of the earthquake at its source. An earthquake has one magnitude. The magnitude does not depend on where the measurement is made. Often, several slightly different magnitudes are reported for an earthquake.

Moment Magnitude, Richter Scale

Magnitude scales, like the moment magnitude, measure the size of the earthquake at its source. An earthquake has one magnitude. The magnitude does not depend on where the measurement is made. Often, several slightly different magnitudes are reported for an earthquake.

Moment Magnitude, Richter Scale

Magnitude scales, like the moment magnitude, measure the size of the earthquake at its source. An earthquake has one magnitude. The magnitude does not depend on where the measurement is made. Often, several slightly different magnitudes are reported for an earthquake.

Tsunami is a Japanese word that means "harbor wave." It is a large wave caused by movements in Earth's outer layer, or crust, which move ocean water. For example, an earthquake or a volcano in the ocean could cause a tsunami.

On September 28, 2004, a magnitude 6.0 earthquake occurred on the San Andreas fault near Parkfield. It ruptured the same segment that ruptured in 1966 and was the seventh earthquake on this stretch of the fault since 1857. Strong shaking was felt for about 10 seconds. What is Your Earthquake Risk?

Volcano Watch Geologists Reexamine Big Earthquake Of 1868

This great earthquake occurred in 1868 and had an estimated magnitude of 7.9. April 2 marks the anniversary of the largest earthquake to occur in the Hawaiian Islands in historic time. This great earthquake occurred in 1868 and had an estimated magnitude of 7.9.

Volcano Watch   Geologists Reexamine Big Earthquake Of 1868

San Francisco earthquake of 1989, also called Loma Prieta earthquake, major earthquake that struck the San Francisco Bay Area, California, U.S., on October 17, 1989, and caused 63 deaths, nearly 3,800 injuries, and an estimated $6 billion in property damage.

There are three main parts to an earthquake: the focus, or origin of the event; the seismic waves; and the fault along which the earthquake occurs.