[June 18, 2018] New paper published on the August 24, 2014 M6.0 South Napa Earthquake
“A new paper published by Nevada Geodetic Laboratory Graduate Student Meredith Kraner uses data from high‐precision continuous GPS stations to observe a 3 mm horizontal expansion of the Earth’s crust prior to and in the vicinity of the August 2014 M6.0 South Napa earthquake. The study is a collaboration with William Holt from Stony Brook University, and Adrian Borsa from Scripps Institution of Oceanography at UC San Diego. The analysis looks at eight years of continuous GPS data leading up to the earthquake and finds that this pattern of horizontal crustal extension repeats every summer. The effect releases pressure on faults in the West Napa fault system, making them more likely to slip during the summer months. We speculate that large seasonal variability in the amount of groundwater in the Sonoma and Napa Valley subbasins may contribute to the observed changes.
Read more in the paper, which has been published in the Journal of Geophysical Research, Solid Earth and is available online here: