Seismicity in Pennsylvania: Evidence for Anthropogenic Events?

Abstract:

The deployment and operation of the USArray Transportable Array (TA) and the PASEIS (XY) seismic networks in Pennsylvania during 2013 and 2014 provide a unique opportunity for investigating the seismicity of Pennsylvania. These networks, along with several permanent stations in Pennsylvania, resulted in a total of 104 seismometers in and around Pennsylvania that have been used in this study.

Event locations were first obtained with Antelope Environmental Monitoring Software using P-wave arrival times. Arrival times were hand picked using a 1-5 Hz bandpass filter to within 0.1 seconds. Events were then relocated using a velocity model developed for Pennsylvania and the HYPOELLIPSE location code.

In this study, 1593 seismic events occurred between February 2013 and December 2014 in Pennsylvania. These events ranged between magnitude (ML) 1.04 and 2.89 with an average MLof 1.90. Locations of the events occur across the state in many areas where no seismicity has been previously reported. Preliminary results indicate that most of these events are related to mining activity. Additional work using cross-correlation techniques is underway to examine a number of event clusters for evidence of hydraulic fracturing or wastewater injection sources.