foreshock

Etymology
From.

Noun

 * 1)  A small earth tremor which precedes the mainshock in an earthquake sequence. Not all mainshocks have foreshocks.
 * 2) Any shock or disturbance that precedes an event

Translations

 * Chinese:
 * Mandarin:
 * Finnish: esijäristys
 * Greek:
 * Hungarian: előrengés
 * Irish: réamhchrith
 * Japanese:
 * Spanish: sismo inicial, sismo premonitor