Data from the 71 stations (30 PASEIS, 41 other) shown on the station map are being used to locate seismic events in Pennsylvania. Data from the PASEIS stations are telemetered to the IRIS Data Managment Center (DMC) for archiving and open distribution under the PE network code. Data from the other networks are also openly available from the IRIS DMC.
Near real-time data from the 71 stations are fed into an EarthWorm system at Penn State for automatic event detection and location. To improve the automatic locations, the arrival times of seismic phases (P & S) are repicked by hand and then used with the HYPOINVERSE code within Seisan to obtain a refined location. The same velocity model, modified from Katz (1955), is used for event location in EarthWorm and HYPOINVERSE. Recent refined event locations are posted on this website. The entire catalog may be downloaded here. The HYPOINVERSE output files are also available and can be downloaded here. The description of these files can be found in the Seisan documentation. Location uncertainties shown on the event page are for an error ellipse computed using a 68% confidence bound and one degree of freedom, and should be considered minimum estimates. Event magnitudes are determined using the local magnitude equation for the eastern U.S. from Kim (1998).
The sources of the events posted to this website are not analyzed. Possible seismic sources include natural earthquakes, mining blasts, and induced seismicity. The United States Geological Survey and the Lamont Doherty Cooperative Seismographic Network do not routinely post mine blast information on their websites. Therefore, event information posted on the PASEIS website can be cross-referenced with the Lamont Doherty Cooperative Seismographic Network website to give an indication of which events could be mine blasts.
Event notifications are provided via email. If you would like to receive automatic email notifications every time a new event is located, please register using the link below. This email will contain the same information found on the event page.