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Related to foreshock: tsunami, aftershock
A minor tremor of the earth that precedes a larger earthquake originating at approximately the same location.
(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
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.