Research suggests the magnitude 6.0 earthquake that rocked California wine country in 2014 may have been caused by an expansion of Earth's crust because of seasonally receding groundwater under the Napa and Sonoma valleys. The vineyard-filled valleys flank the West Napa Fault, which produced the quake that killed one person, injured several hundred and caused more than $500 million in losses. "We think it's more of a localized effect, something related to the groundwater system. Co-authors were William E. Holt of Stony Brook University and Adrian A. Borsa of the Scripps Institution of Oceanography at the University of California, San Diego. The early morning Napa quake on Aug. 24, was the largest to hit the San Francisco Bay Area since the magnitude 6.9 Loma Prieta earthquake of Oct. 17, 1989.

Source: ABC News June 13, 2018 22:52 UTC