Seismic hazard assessment at the Fallon, Nevada, Frontier Observatory for Research in Geothermal Energy site

Enhanced geothermal systems (EGS) technology aims to engineer a productive geothermal reservoir in regions of hot, but low permeability, rocks. In any EGS operation, the rock mass requires stimulation by high pressure injection of fluids, which has the potential to induce seismicity. To address the seismic hazard specifically, a probabilistic seismic hazard assessment (PSHA) is often required and is generally part of an induced seismicity mitigation plan (ISMP). A specific PSHA for the proposed Fallon, Nev., FORGE site is outlined below that relies solely on hypothetical stimulation scenarios and analog sites to assess the hazard of induced seismicity in the absence of local microseismicity. Partially due to the lack of existing seismicity at the site and partially to arrive at conservative estimates of the hazard, the PSHA is calculated for a range of b-values. Results indicate that the conservative estimates of seismic hazard at locations having significant, sensitive infrastructure near the proposed site are very low.