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

Sniffer dogs in Japan helped rescuers Friday make a final sweep of a shopping mall wrecked by an explosion after a big earthquake, as the death toll from the tremor three days earlier hit 35.

From Barron's ● Jul. 31, 2026

The devastating earthquake that shook the country last month also slowed the progress.

From The Wall Street Journal ● Jul. 30, 2026

They slept between tables and chairs, where others congregated to watch news about the earthquake or wait in line for a warm meal.

From Barron's ● Jul. 30, 2026

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

They had just crossed the bridge from Magpie Island to the mainland when the earthquake hit.

From "Earthquake Terror" by Peg Kehret

"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

Tuesday hit Kumamoto prefecture, where a pair of earthquakes a decade ago killed more than 200 people.

From The Wall Street Journal ● Jul. 28, 2026

At least 5,398 people were killed in the June 24 earthquakes, with hundreds of buildings destroyed, particularly in the hardest-hit state of La Guaira in the country's coastal north.

From Barron's ● Jul. 23, 2026

Venezuela's interim president Delcy Rodriguez has pledged to deliver 4,000 homes by year's end to those displaced by the earthquakes, including an estimated 23,000 who are now homeless.

From Barron's ● Jul. 23, 2026

“I’ve felt no earthquakes and there’ll be no eruption,” was Truman’s emphatic reply.

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

Related Words

• shock
• temblor
• upheaval