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 seismic

earthquake

/ ûrth′kwāk′ /

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 .)

Notes

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 Words From

• pre·earthquake 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

To plumb deeper structure all the way down to Earth’s core, SinoProbe II will rely on several thousand “passive” seismometers across China, listening for earthquakes near and far.

From Science Magazine

The primary upset was viewed as a political earthquake at the time as Crowley was then the fourth highest-ranking congressional Democrat, serving as the chair of the Democratic Caucus.

From Salon

The ground trembled so violently some people thought there was an earthquake.

From BBC

"This could also apply to new terrain that forms after earthquakes or landslides where you have more or less the same situation, a mineral or rock-based substrate."

From Science Daily

The dam is now undergoing a retrofit that will raise its crest by 10 feet and fortify the dam for earthquake safety.

From Los Angeles Times

Related Words

• shock
• temblor
• upheaval