CLASSIFYING ANSS CATALOG EARTHQUAKES AS NATURAL, POTENTIALLY INDUCED, OR LIKELY INDUCED IN THE FAYETTEVILLE SHALE DEVELOPMENT AREA OF NORTH-CENTRAL ARKANSAS

North-central Arkansas has seen an increase in unconventional resource development and seismicity within the Fayetteville Shale development area (FSDA) since 2009. The FSDA is historically seismically active, and the increase in seismic activity is likely a combination of both natural and induced earthquakes. A feasibility study evaluated 296 FSDA earthquakes in the Advanced National Seismic System (ANSS) catalog from 2012 through 2016, classifying the events as natural, potentially induced, or likely induced. The induced earthquakes are associated with hydraulic fracturing of production (HFP) wells and the injection of fluids in saltwater disposal (SWD) wells. For the HFP well evaluation, a questionnaire was developed to help classify the earthquakes. In addition, a matched filter analysis provided evidence to raise some HFP event classifications from potentially to likely induced. Based on this method, a catalog of FSDA earthquakes was created that classified each earthquake as natural, potentially induced, or likely induced. This catalog can be used for the hazard calculation in future U.S. National Seismic Hazard Map updates. Based on the results of this study, this method will be used to evaluate the remaining ANSS catalog earthquakes in the FSDA from 2009 to present and with suitable modification, could be used to process and classify ANSS catalog earthquakes occurring within other designated zones of suspected induced seismicity in the Central and Eastern United States (CEUS).