earthquake

[urth-kweyk]

noun

1. a series of vibrations induced in the earth's crust by the abrupt rupture and rebound of rocks in which elastic strain has been slowly accumulating.

   Synonyms: temblor, seism, shock, tremor, quake

2. something that is severely disruptive; upheaval.

earthquake

/ ˈɜːθˌkweɪk /

noun

1. a sudden release of energy in the earth's crust or upper mantle, usually caused by movement along a fault plane or by volcanic activity and resulting in the generation of seismic waves which can be destructive

earthquake

1. A sudden movement of the Earth's lithosphere (its crust and upper mantle). Earthquakes are caused by the release of built-up stress within rocks along geologic faults or by the movement of magma in volcanic areas. They are usually followed by aftershocks.

2. See Note at fault

earthquake

1. A tremor of the surface of the Earth, sometimes severe and devastating, which results from shock waves generated by the movement of rock masses deep within the Earth, particularly near boundaries of tectonic plates. (See fault, Richter scale, and seismology.)

Earthquakes are particularly likely where such plates are sliding past each other, as in the San Andreas Fault.

Earthquakes cannot be accurately predicted, although the likelihood of a region's suffering an earthquake can be estimated.

Other Word Forms

• preearthquake adjective

Word History and Origins

Origin of earthquake¹

1300–50; Middle English erthequake ( earth, quake ), replacing Old English eorthdyne ( din ¹ )

A Closer Look

Fractures in Earth's crust, or lithosphere, where sections of rock have slipped past each other are called faults.Earthquakes are caused by the sudden release of accumulated strain along these faults, releasing energy in the form of low-frequency sound waves called seismic waves. Although thousands of earthquakes occur each year, most are too weak to be detected except by seismographs, instruments that detect and record vibrations and movements in the Earth. The point where the earthquake originates is the seismic focus, and directly above it on Earth's surface is the earthquake's epicenter. Three kinds of waves accompany earthquakes. Primary (P) waves have a push-pull type of vibration. Secondary (S) waves have a side-to-side type of vibration. Both P and S waves travel deep into Earth, reflecting off the surfaces of its various layers. S waves cannot travel through the liquid outer core. Surface (L) waves—named after the nineteenth-century British mathematician A.E.H. Love—travel along Earth's surface, causing most of the damage of an earthquake. The total amount of energy released by an earthquake is measured on the Richter scale. Each increase by 1 corresponds to a tenfold increase in strength. Earthquakes above 7 on the Richter scale are considered severe. The famous earthquake that flattened San Francisco in 1906 had a magnitude of 7.8.

Example Sentences

Local authorities have also flagged the region as being at lower risk of earthquakes compared to other potential sites in Japan.

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The study, published Nov. 19 in Science Advances and supported by National Science Foundation grants, introduces a new factor that could reshape how scientists interpret fault behavior linked to major earthquakes.

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The BGS said about 300 naturally occurring earthquakes happen in the UK every year, but only about 30 are of significant power to be felt by people.

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At least five people have been killed, including one child, and more than 450 injured after a 5.5 magnitude earthquake hit Bangladesh.

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The "swarm" of tens of thousands of earthquakes near the Greek island of Santorini earlier this year was triggered by molten rock pumping through an underground channel over three months, scientists have discovered.

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Related Words

• shock 
• temblor 
• upheaval