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earthquake vs. aftershock

earthquake

[urth-kweyk] / ˈɜrθˌkweɪk /

noun

a series of vibrations induced in the earth's crust by the abrupt rupture and rebound of rocks in which elastic strain has been slowly accumulating.

Synonyms:

temblor, seism, shock, tremor, quake
something that is severely disruptive; upheaval.

aftershock

[af-ter-shok, ahf-] / ˈæf tərˌʃɒk, ˈɑf- /

noun

a small earthquake or tremor that follows a major earthquake.
the effect, result, or repercussion of an event; aftermath; consequence.

The aftershock of the bankruptcy was felt throughout the financial community.