CONTINENTAL PLATE INTERIORS ARE NOT TOTALLY

INACTIVE GEOLOGICALLY

SOME INTRAPLATE EARTHQUAKES, SUCH AS THOSE IN THE CENTRAL U.S. (NEW MADRID) SEISMIC ZONE OCCUR, PRESUMABLY BECAUSE SMALL MOTIONS WITHIN THE PLATE INTERIOR CAUSE MOTION ON FOSSIL FAULTS

ALTHOUGH THESE EARTHQUAKES ARE RARER THAN THOSE DUE TO THE RAPID MOTION AT PLATE BOUNDARIES, THEY CAN BE LARGE

(MAGNITUDE 7 EARTHQUAKES IN 1811 & 1812)