Healdsburg Fault

The Healdsburg Fault is a seismically active geological feature associated with the Santa Rosa Plain and the Alexander Valley, in Sonoma County, California, United States.

The maximum credible earthquake expected to be generated from the Healdsburg Fault is estimated to be about 7.5 on the Richter scale.

[1] The last major event in Sonoma County were the 1969 Santa Rosa earthquakes, a magnitude 5.6 and 5.7 doublet that occurred on this fault.

[2] The Rodgers Creek Fault passes through Sonoma Mountain and its north end terminates within Santa Rosa.

The upper soil surface above the Santa Rosa Plain is composed of Plio-Pleistocene alluvial fan deposits.