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Related to foreshocks: Seismic waves, Aftershocks


A minor tremor of the earth that precedes a larger earthquake originating at approximately the same location.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.


(Geological Science) a relatively small earthquake heralding the arrival of a much larger one. Some large earthquakes are preceded by a series of foreshocks. Compare aftershock
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014


(ˈfɔrˌʃɒk, ˈfoʊr-)

a relatively small earthquake that precedes a greater one by a few days or weeks and originates at or near the focus of the larger earthquake.
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.foreshock - a tremor preceding an earthquake
earth tremor, microseism, tremor - a small earthquake
Based on WordNet 3.0, Farlex clipart collection. © 2003-2012 Princeton University, Farlex Inc.
References in periodicals archive ?
There have been foreshocks of this seismic change, in areas like employer brand, employee value proposition (EVP) and employee engagement, and there are those who make the argument that employee experience is a synonym of engagement, but clumping these things together misses a couple of key elements of what makes employee experience so powerful.
"Here we use a new, highly complete earthquake catalog to show that most mainshock earthquakes in southern California are preceded by elevated seismicity rates -- foreshocks -- in the days and weeks leading up to the event," said the study.
Earthquake clusters are different from short-term 'swarms.' Clusters of foreshocks and aftershocks can span several months before and after a big earthquake.
The expanded earthquake catalog reveals previously undetected foreshocks that precede major earthquakes as well as the evolution of swarms of earthquakes.
However, the group does note that in some cases, random behavior by animals might be connected to foreshocks or the initial stage of an already underway quake.
(2011) stated that just the main earthquakes must be considered in the recurrence analysis of earthquakes and all dependent events such as foreshocks and aftershocks must be excluded from the catalog before starting any calculations.
What remains unknown, and disconcerting, is whether the high number of aftershocks were just that, or "foreshocks" preceding another large quake.
Despite intensive analysis of factors such as increases in radon gas concentrations, changes in electromagnetic activity, foreshocks and even unusual animal behavior, researchers have been unable to uncover reliable precursors to these events.
Damage is widespread due to a series of earthquake including two foreshocks on 14 April and the magnitude 7.3 main quake on 16 April.
Galvanized by the Wall Street bailouts following the 2008 financial crisis, Tea Party activists challenged the GOP establishment and triggered the foreshocks of the Trump earthquake.