Pymatuning Earthquake

The largest recorded Pennsylvania earthquake occured about 15 miles from Sharon, Northwestern Pennsylvania September 25, 1998. The earthquake measured 5.2 on the Richter scale and was felt over approximatley 200,000 square kilometers in the northern United States and southern Canada. The earthquake is commonly called the Pymatuning earthquake because the proximity of the epicenters to the Pymatuning Reservoir. The area of the earthquake is surrounded by glacial till and valley fill, which during the earthquake experienced more shaking than the adjacent bedrock. The glacial fill helped to create the large area over which the earthquake was felt. Here are the large scale and small scale Mercalli Intensity maps of the Pymatuning earthquake. Information gathered from USGS website.

Large scale intensity map

Small scale intensity map

Link to the bulletin from USGS 1998 of the Pymatuning earthquake