- 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.
- something that is severely disruptive; upheaval.
Origin of earthquake
Synonyms for earthquake
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
- 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 destructiveRelated adjective: seismic
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Online Etymology Dictionary, © 2010 Douglas Harper
- 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. See Note at fault.
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.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
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.
The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.