Anthropogenic Seismicity Rates and Operational Parameters at the Salton Sea Geothermal Field

Emily E. Brodsky, & Lia J. Lajoie

Published August 2, 2013, SCEC Contribution #1752

Geothermal power is a growing energy source; however, efforts to increase production are tempered by concern over induced earthquakes. Although increased seismicity commonly accompanies geothermal production, induced earthquake rate cannot currently be forecast based on known volumes of fluid injection or any other operational parameter. Here we show that at the flash facilities in the Salton Sea Geothermal Field, the total volume of fluid extracted or injected tracks the long-term evolution of seismicity. However, for recent years net fluid volume (extracted-injected) is better correlated with seismicity. After correcting for the variable aftershock rate, we model the background earthquake rate with a linear combination of injection and net production rate that allows us to track the secular evolution of the field. The number of earthquakes per fluid volume injected decreases gradually over time. This new analysis of induced seismicity provides a template for future evaluation of hazard directly based on measureable, controllable operational quantities.

Citation
Brodsky, E. E., & Lajoie, L. J. (2013). Anthropogenic Seismicity Rates and Operational Parameters at the Salton Sea Geothermal Field. Science, 341, 543-546. doi: 10.1126/science.1239213.