Snow and rain tug on earthquake faults in California | Science News


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Snow and rain tug on earthquake faults in California

Seasonal changes in water weight can set off small tremors

7:00am, July 3, 2017
Sierra Nevada mountains

ON THE REBOUND  Weighed down with water during wet winters, California’s northern mountain ranges — like the Sierra Nevada, shown — rebound during dry summers. This seasonal flexing leads to an uptick in small quakes along some faults, new research finds.

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Winter weather brings seismic tremors. A new study reveals how water buildup and runoff throughout the year can increase stress along faults in California, triggering small earthquakes.

“This kind of observation is extremely important to constrain our models of earthquakes,” says Jean-Philippe Avouac, a geologist at Caltech who was not involved in the study. Improved models could ultimately help scientists better forecast seismic activity.

Snow and rain compress mountain ranges in Northern California several millimeters during wet winter months. But with the weight of the water gone during the dry summers, the landscape lifts back up. This seasonal squeeze and release of the terrain puts stress on nearby faults, which can set off more small earthquakes.

Researchers compared observations of ground movement from 661 GPS stations in California with the state’s earthquake record from 2006 to 2014. The

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