The Pennsylvania State Seismic Network (PASEIS) and Seismicity Within the Commonwealth of Pennsylvania

Abstract The Pennsylvania State Seismic Network (PASEIS), established to monitor both natural and induced seismic events within the Commonwealth of Pennsylvania, began in 2005 with a limited number of stations and expanded to its current configuration of more than 30 stations in 2016. PASEIS data are recorded continuously and made openly available in near real time under the PE network code via the EarthScope Data Management Center. At Penn State, the data are ingested into the Earthworm software package for automated seismic event detection, location, and magnitude estimation. Earthworm results are reviewed and revised by a seismic analyst and posted to the PASEIS website (see Data and Resources). Between November 2016 and December 2024, 1305 seismic events were detected and located (47 earthquakes, 4 mine collapse events, and 1254 mine and quarry blasting events). During that time interval, no induced events related to hydraulic fracturing or wastewater disposal were detected. The average event magnitude is ML 1.7 for blasts, and analysis of the Gutenberg–Richter relationship suggests magnitude of completeness is ∼1.5 with a b-value of 0.8 for the earthquakes, although limited data makes statistical analysis problematic. The average horizontal epicentral location uncertainty for all events is 1.2 km. By providing open-access data from a statewide network, PASEIS is leading to a greater understanding of seismicity and tectonic stresses within and surrounding Pennsylvania, and thus seismic hazards.