前ぜん震しん

noun

foreshock

Seismological term for a smaller earthquake that precedes a larger mainshock. Often contrasted with 余震 (aftershock).

See also: 余震

• 大おおきな地じ震しんの前まえに、小ちいさな前ぜん震しんが観かん測そくされた。

  A small foreshock was observed before the large earthquake.