i Register
In some senses, foreshock is marked as figuratively. Watch for register when choosing this word.
noun
A small earth tremor which precedes the mainshock in an earthquake sequence.
Any shock or disturbance that precedes an event
The FY 1981 increases in defense — something of a "foreshock" to the rapid rise in defense spending over the next several years — were prompted by the fall of the Shah in Iran and the Soviet invasion of Afghanistan.