CHAPEL HILL, N.C., May 3 (UPI) — The southeastern United States isn’t known for its seismic activity, but the region does experience the odd earthquake.

A new study — published in the Journal of Geophysical Research: Solid Earth — offers an explanation for the phenomenon.

Most earthquakes occur near plate boundaries and major fault lines. The southeastern corner of the United States lies in the middle of the North American Plate, far from the seismically active margins.

However, new analysis suggests the plate’s interior continues to lose bits and pieces of its mantle. As fragments break off and sink toward Earth’s interior, the mantle is left thinner and more brittle — and more susceptible to the fault slipping that triggers earthquakes.  Source