Virginia is a State of considerable seismic activity, although the earthquakes are rarely strong. Thirty-five shocks, intensity MM V or greater (Modified Mercalli Scale), are listed with epicenters within its borders. The locations of several of the older events are not precise; thus, the above count i subject to alteration. A detailed study of Virginia earthquakes by G. A. Bollinger and M. G. Hopper of the Virginia Polytechnic Institute and State University listed 137 shocks (71 from 1774 to 1899, 66 from 1900 to 1970). Many of these were felt with intensities below MM V.