Risk of Seismicity from Potential Direct-Use Operations in the Appalachian Basin Geothermal Play Fairway Project

Abstract

A collaborative effort between Cornell University, Southern Methodist University, and West Virginia University has been sponsored by the US Department Of Energy to perform a Geothermal Play Fairway Analysis of the low temperature direct use potential for portions of the Appalachian sedimentary basin in New York, Pennsylvania and West Virginia - abbreviated here as GPFA-AB. One risk factor - of several analyzed for the GPFA-AB - is whether a candidate location is near an active fault, and thereby potentially susceptible to induced seismicity from geothermal operations. Existing fault maps do not share the GPFA-AB boundaries or scale. Hence, their use leads to problems of uneven coverage, varying interpretation of faults vs. lineaments, and different mapping scales. For more uniformity across the GPFA-AB region, we use an analysis of gravity and magnetic fields. Multiscale-edge Poisson wavelet analyses of potential fields ("worms") have a physical interpretation as the locations of lateral boundaries in a source distribution that exactly generates the observed field. Not all worms are faults, and of faults, only a subset might be active. Also, worms are only sensitive to steeply dipping structures. To identify some active structures, we plot worms and intra-plate earthquakes from the NEIC, and EarthScope TA catalogs. Worms within a small distance of epicenters are tracked spatially. To within errors in location, this is a sufficient condition to identify structures that might be active faults - which we categorize with higher risk than other structures. Plotting worms within World Stress Map σ1 directions yields an alternative approach to identifying activatable structures. Here, we use worms to identify structures with strikes favorably oriented for failure by Byerlee's law. While this is a necessary criterion for fault activation it is not a sufficient one - because we lack detailed information about stress magnitudes throughout the GPFA-AB region. Details from both approaches and their resulting GPFA-AB risk maps will be presented at the meeting.