Temporal variation in the magnitude-frequency distribution during the Guy-Greenbrier earthquake sequence

The recent increase in earthquake activity in the central U.S. has led to concerns about the hazard posed by induced earthquakes. Understanding earthquake phenomena and monitoring in all settings can be improved by the detection of small events; however, the catalog of induced earthquakes is incomplete for small events due to the sparse instrumentation. This is particularly true in settings of low background seismicity, like the central U.S. We apply single-station template matching to detect small earthquakes during the Guy-Greenbrier sequence in central Arkansas and find over 100 times more earthquakes than are registered in the Advanced National Seismic System catalog between July 2010 and October 2011. A complete catalog over nearly 4 units of magnitude enables us to analyze the magnitude-frequency distribution of induced earthquakes. We find that earthquakes deviated from the Gutenberg-Richter statistics during the operation of nearby injection wells but returned to Gutenberg-Richter statistics after the wells were shut in.