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.

something that is severely disruptive; upheaval.

noun

convulsion , fault , macroseism , microseism , movement , quake , quaker , seimicity , seism , seismism , shake , shock , slip , temblor , trembler * , undulation , upheaval , tremblor , aftershock , earthshock , earth tremor , foreshock , seismology , trembler , tremor