Terme préférentiel

Foreshock

Description

Relatively smaller earthquake that precedes the largest earthquake (which is termed the mainshock) in an earthquake sequence. Foreshocks usually originate at or near the focus of the mainshock and may precede the latter by seconds to weeks. Not all mainshocks have foreshocks. See also aftershock.
Small earthquakes preceding the main earthquake in a series of events located in the same area. Not all mainshocks have foreshocks.

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