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Thursday, May 15, 2014

Study: Watering California's Farm Industry Is Causing Earthquakes

Posted By on Thu, May 15, 2014 at 2:02 PM

click to enlarge We've got the shakes - WIKIMEDIA COMMONS
  • Wikimedia Commons
  • We've got the shakes

Forget fracking. A spike in earthquakes in California in recent years may be caused by the state's bountiful agricultural industry.

There's been a steady increase in seismic activity over the past 30 years in an area near Monterey County, but scientists noticed something else, something a little curious: the temblors were often seasonal -- and they got worse in dry years.

It could be in the water. Aquifers underneath the fertile Central Valley are being pumped to quench thirsty almond groves, peach orchards and other crops that provide 25 percent (!) of America's food. Water is heavy -- and pumping it out of the ground, thereby reducing the weight on the fault, might be what is making quiet faults active, according to the Los Angeles Times.

The Central Valley is supposed to be dry land, and it's productive farmland, thanks only to irrigation. Indeed, one-sixth of all irrigated farmland in the United States is in the Central Valley, the US Geological Survey said in a recent report. This steady stream of water allows farmers to keep producing crops like almonds, which require lots of water (but can then be sold to buyers overseas for lots of money).

It's a combination of groundwater pumping and importing water from places like the Sierras that irrigates the Valley. Scientists at UC Berkeley and other universities were put on the trail of linking groundwater pumping to earthquakes by noticing that mountains near the Valley were growing taller more quickly than other mountains -- about by 3 millimeters a year.

The Central Valley's aquifer has been pumped steadily for the past 150 years. The hypothesis is simple: less water means less weight on faults and tectonic plates and less weight makes them more active, and the researchers pointed to an increase in shakes in an area called Parkfield as evidence of the theory at work.

A scientist with the US Geological Survey called the theory "very plausible," the LA Times noted.

There's a fair amount of hoopla in certain coastal areas of the state over fracking, the practice of unleashing petroleum deposits by shooting a high pressure mixture of water and unknown materials (it's a secret!) into the ground. Gov. Jerry Brown has signed off on allowing more fracking in California, despite evidence across the country that fracking makes areas seismically unsafe.

So imagine this: an area with a low groundwater table, pumped out because of a drought that's simultaneously being fracked, that also happens to be near a major active fault (of which there are a few in California). What could go wrong? Looks like we may find out.

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About The Author

Chris Roberts

Chris Roberts has spent most of his adult life working in San Francisco news media, which is to say he's still a teenager in Middle American years. He has covered marijuana, drug policy, and politics for SF Weekly since 2009.


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