Remote Triggering Inside Versus Outside Geothermal Fields

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Remote triggering by large earthquakes at regional distances has been globally observed and intensely studied since the 1992 Mw 7.3 Landers earthquake in California. However, most of the previous studies were conducted at spatial scales of hundreds of kilometers and did not differentiate the actual operational geothermal fields with anthropogenic setting and their adjacent fault zones with natural setting. A two-year project is proposed for detailed analyses of the remotely triggered seismicity to examine hypothesis that geothermal fields respond differently from their vicinity to remote earthquakes due to the stress-state changes that are associated with the anthropogenic activity inside the geothermal field. The expected results will improve knowledge of the effect of pore fluid pressure on earthquake initiation and interaction and contribute to models of remotely triggered and induced seismicity, which will be important for evaluating the potential of future seismic hazards in geothermal fields due to remote earthquakes and human activity. In this proposed work, three operational geothermal fields under active tectonic settings in California corresponding to three large distant earthquakes are selected. The focus of this research is to compare different behaviors between each geothermal field (~10x10 km^2) and their adjacent fault zones (~100x100 km^2) that are split into several subareas. The results will address the following questions: (1) How does seismicity rate change inside and outside the geothermal fields responding to each remote earthquake? (2) How different are the stress fields inside and outside the geothermal fields? (3) How do shallow and deep earthquakes respond to remote triggering? (4) Is there any correlation between the net production rate and the seismicity rate inside the geothermal field? (5) What is the difference in the seismic velocity structure and in situ Vp/Vs inside and outside the geothermal fields?