https://apnews.com/ef3a2a7eccfc43189b8b8728bf0f8a2f

NAPA, Calif. (AP) — 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.