earthquake

American  

[urth-kweyk] / ˈɜrθˌkweɪk /

noun

earthquakes plural

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.

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earthquake British  

/ 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

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earthquake Scientific  

/ 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

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earthquake Cultural  

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.)

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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.

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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

Derived Forms

• preearthquake
  adjective

Inflected Forms

Nouns

• earthquakes
  plural

Etymology

Origin of earthquake

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

Compare meaning

How does earthquake compare to similar and commonly confused words? Explore the most common comparisons:

• earthquake vs. aftershock
• temblor vs. earthquake

Explanation

If you're visiting your friend in California and her house starts to shake, you might be experiencing an earthquake, which is the shaking of the surface of the earth that happens when there's movement deep underground. Earthquake is one of those words that means exactly what it sounds like: the earth is quaking. Earthquakes happen along "fault lines," the places where the big plates of the earth meet and rub up against each other during volcanic activities. We also use earthquake metaphorically, to talk about something that causes a violent upheaval.

Example Sentences

See Examples For:

earthquake earthquakes

The JMA measured the earthquake magnitude at 7.1 and the US Geological Survey later placed it at 6.8.

From BBC ● Jul. 29, 2026

A magnitude 4.2 earthquake was reported Tuesday at 7:40 p.m., eight miles from Healdsburg, Calif., according to the U.S.

From Los Angeles Times ● Jul. 29, 2026

A major earthquake that severely damaged a shopping mall and a factory in Japan killed at least 13 people, officials said Wednesday, as rescuers desperately tried to reach survivors feared trapped in the wreckage.

From Barron's ● Jul. 29, 2026

Investors are also closely watching any disruption to business operations following a major earthquake in the southern Japanese prefecture of Kumamoto.

From The Wall Street Journal ● Jul. 29, 2026

The backup generators that had kicked in after the earthquake sputtered out.

From "Meltdown" by Deirdre Langeland

"For the next week or so, especially the next two to three days, we would like people to watch out for potential earthquakes with a maximum seismic intensity of 7," a JMA official said.

From BBC ● Jul. 29, 2026

A month after the earthquakes, search efforts continue for victims whose remains might be buried underneath rubble, but operations have evolved to focus on post-earthquake humanitarian aid and rebuilding.

From Barron's ● Jul. 23, 2026

One of the phenomena examined in “Out of Time” is why more Pompeiians didn’t flee during or after the foreshadowing earthquakes, and that’s a fascinating area of study all its own.

From The Wall Street Journal ● Jul. 21, 2026

The morning of Alfonzo’s debut, his sister and stepmother, who had been missing since two powerful earthquakes devastated Venezuela last month, were found dead.

From Los Angeles Times ● Jul. 20, 2026

Were these small eruptions and intermittent earthquakes the whole of Mount St. Helens’s show?

From "Mountain of Fire" by Rebecca E. F. Barone

Related Words

• shock
• temblor
• upheaval