Study ties earthquake activity to So. Calif. geothermal power plant

Researchers say they've found a strong correlation between seismic activity and operations at a California geothermal power production facility. Scientists at the University of California, Santa Cruz, said that was the result of an analysis of earthquakes in the area around the Salton Sea Geothermal Field in southern California. "We show that the earthquake rate in the Salton Sea tracks a combination of the volume of fluid removed from the ground for power generation and the volume of wastewater injected," lead study author Emily Brodsky said. "The seismicity is clearly tracking the changes in fluid volume in the ground." Brodsky and coauthor Lia Lajoie studied earthquake records for the region from 1981 through 2012, comparing earthquake activity with production data for the geothermal power plant, including records of fluid injection and extraction. The Salton Sea power plant is a "flash-steam facility" which pulls hot water out of the ground, flashes it to steam to run electricity-generating turbines, and recaptures as much water as possible for injection back into the ground. "The findings show that we might be able to predict the earthquakes generated by human activities," said Brodsky, a professor of Earth and planetary sciences. "To do this, we need to take a large view of the system and consider both the water coming in and out of the ground." The location of the Salton Sea geothermal field at the southern end of the San Andreas fault is cause for concern due to the possibility of inducing a damaging earthquake, she said. "It's hard to draw a direct line from the geothermal field to effects on the San Andreas fault, but it seems plausible that they could interact."