Evidence of Active Quaternary Deformation on the Great Valley Fault System near Winters, Northern California

Abstract The Great Valley fault system defines the tectonic boundary between Coast Ranges and Central in California, is active throughout Quaternary, has been source of several significant (M > 6) historic earthquakes, including 1983 M 6.5 Coalinga earthquake 1892 Vacaville–Winters sequence. However, locations geometries individual faults are poorly constrained, slip rates paleoearthquake chronology largely unknown. Here, we report geomorphic subsurface geophysical evidence surface-deforming displacement on a strand west Winters, California. Detailed mapping high-resolution seismic reflection tomography survey along an ∼800 m profile across Bigelow Hills document fault, which call West Winters system, with apparent east side-up surficial geologic units. These data together suggest that latest Quaternary. Together local reports from time, this raises possibility may have ruptured deformed surface during 6 Future earthquakes vertical structures could hazard implications, given region’s low relief presence major water conveyance infrastructure.