Earthquakes in Pennsylvania
Pennsylvania experiences a relatively low level of earthquake activity compared to active states such as Alaska and California. Not only do earthquakes occur in our Commonwealth, but parts or all of Pennsylvania has been subject to the effects of earthquakes located outside our borders.
You can view earthquake epicenter data as part of the DCNR Interactive map.
The Survey has an epicenter (location) map and catalog of all recorded seismic events from 1724 to 2003 in and near Pennsylvania: Map 69, Earthquake Catalog and Epicenter Map of Pennsylvania. A simplified version of this map provides a quick overview of earthquake epicenters in and near Pennsylvania.
In 1998, the largest earthquake ever recorded in Pennsylvania, known as the Pymatuning Earthquake, occurred in the region of Pymatuning Lake in northwestern Pennsylvania.
A swarm of small earthquakes occurred near Dillsburg, York County from 2008 until early 2011.
Our Educational Series 10 publication, Earthquake Hazard in Pennsylvania, provides an extended discussion on the nature, occurrence, history, and hazards of earthquakes in the Commonwealth.
If you feel an earthquake, you can report your experience to the U. S. Geological Survey at “Did You Feel It?
The Pennsylvania Geological Survey has a seismograph established at its Middletown location. This seismograph is capable of recording the largest earthquakes in the world. Two records from this station are:
- Seismogram of the August 12, 2010, 7.1 magnitude (M) earthquake in Ecuador.
- Seismogram of the July 16, 2010, 3.6 magnitude (M) earthquake in Maryland.
- Seismogram of the January 12, 2010, 7.0 magnitude (M) earthquake in Haiti.
- Seismogram of the April 21, 2006, 7.6 magnitude (M) earthquake in eastern Siberia.
- Seismogram of the October 7, 2005, 7.6 magnitude (M) earthquake in Pakistan. Though not as powerful as the March 28, 2005 earthquake in Sumatra, it was the deadliest earthquake in 2005 with nearly 90,000 people killed.
- Seismogram of the December 26, 2004, 9.0 M earthquake in the Indian Ocean off the coast of Sumatra. This was the largest earthquake in the world since the 1964 Alaska earthquake. The second large Sumatra earthquake on March 28, 2005 was a 8.7 M, the second largest since 1964.
More information from other web sites
From the USGS
From the Lamont-Doherty Cooperative Seismic Network
From Pennsylvania Universities