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

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

"Many deaths feared after strong earthquake wreaks havoc in southern Japan" says the paper in a separate headline, next to a birds-eye shot of a partially fallen bridge.

From BBC ● Jul. 29, 2026

Inside, I feel the earthquake start to rumble, the pressure building, the explosion coming.

From "Wayward Creatures" by Dayna Lorentz

In 2016, a pair of earthquakes killed 277 people and injured 2,800 others.

From BBC ● Jul. 29, 2026

Two earthquakes in April 2016 struck Kumamoto 28 hours apart.

From The Wall Street Journal ● Jul. 28, 2026

"The earthquakes have disrupted lives, damaged critical infrastructure, and created new challenges for Venezuela's recovery," said Susana Cordeiro Guerra, World Bank Vice President for Latin America and the Caribbean.

From Barron's ● Jul. 23, 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

"You can count on that. This is a big fault zone for earthquakes."

From "A Short History of Nearly Everything" by Bill Bryson

Related Words

• shock
• temblor
• upheaval