foreshock

foreshock [fawr-shok, fohr-] Word Origin noun Geology.

1. 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.

Origin of foreshock First recorded in 1900–05; fore- + shock1 British Dictionary definitions for foreshock foreshock noun

1. a relatively small earthquake heralding the arrival of a much larger one. Some large earthquakes are preceded by a series of foreshocksCompare aftershock