earthquake

American  

[urth-kwayk] / 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

He and his family lost their home in an earthquake in 2015, and became displaced for months.

From BBC ● Oct. 6, 2026

Highway maintenance, railroad scheduling and earthquake detection were among the civilian activities affected.

From The Wall Street Journal ● Oct. 4, 2026

If the stress levels rise at different times instead, an earthquake rupture may be more likely to stop at the junction.

From Science Daily ● Oct. 2, 2026

The family arrived “right before the Northridge earthquake, so that was our welcome to L.A.,” he says, adding that his family was living nearby in Van Nuys.

From Los Angeles Times ● Oct. 2, 2026

If Ridge was right, if an earthquake was on its way, shouldn’t they tell someone?

From "The First State of Being" by Erin Entrada Kelly

The park service said earthquakes during the 2018 Kīlauea volcano eruption and summit collapse had damaged the cliffs near the arch.

From BBC ● Oct. 2, 2026

Nobody knows where the Shakespeare nickname came from, but city officials designated the bridge as L.A.’s Historic-Cultural Monument No. 126 in 1974 and retrofitted it in the 1990s to better withstand earthquakes.

From Los Angeles Times ● Oct. 2, 2026

The team then incorporated a 1,000-year record of past earthquakes assembled from several types of evidence.

From Science Daily ● Oct. 2, 2026

Goldfinger has been investigating the possibility of linked earthquakes for decades, and the roots of the new research stretch back to an ocean expedition in 1999.

From Science Daily ● Sep. 24, 2026

To Crandell, the earthquakes appeared too far away for concern; to Malone, it seemed like Crandell was looking at bad data.

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

Related Words

• shock
• temblor
• upheaval