USA:

Wastewater Wells, Geothermal Power Triggering Earthquakes (NPR)

Credit: Alyson Hurt / NPR

The continental U.S. experiences small earthquakes every day. But over the past few years, their numbers have been increasing. Geoscientists say the new epidemic of quakes is related to industrial wastewater being pumped into underground storage wells.

Now there's new research that reveals two trigger mechanisms that may be setting off these wastewater quakes — other, larger earthquakes (some as far away as Indonesia), and the activity at geothermal power plants.

In this week's issue of the journal Science, geoscientist Emily Brodsky at the University of California, Santa Cruz, reports that the production of geothermal energy is a trigger mechanism for mini-quakes.


The power plant in question, near Southern California's Salton Sea, extracts hot water from beneath Earth's surface and turns it to steam to make electricity, then returns most of it underground. "What we found," Brodsky says, "is that the earthquake rate correlates quite strongly with the extraction of water from the field" underground.

On average, extracting half a billion gallons of water per month resulted in one detectable earthquake every 11 days.

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