foreshock
nounEtymology From fore- + shock.
1
Geography, Geology, Natural sciences, Seismology A small earth tremor which precedes the mainshock in an earthquake sequence.
2
Figuratively 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.1991, D. Roderick Kiewiet, Mathew D. McCubbins, The Logic of Delegation - Page 88: