Oregon-led team confirms 1838 and 1890 earthquakes occurred on San Andreas Fault

Ashley Streig shows wood chips found in sediment of a pre-1906 earthquake
Ashley Streig shows wood chips found in sediment of a pre-1906 earthquake

Doctoral student Ashley Streig experienced her first big earthquake in 1989, at age 11, when the Loma Prieta quake interrupted baseball's World Series and drove her family out of the house to camp outside. The experience ignited an interest in seismology.

This month, Streig's research, which took her into the field over several years, has resulted in a published study that documents the first geologic evidence that supports historical narratives for two earthquakes in the 68 years prior to San Francisco's devastating 1906 disaster.

Her study, co-authored with her UO adviser Ray Weldon, a professor of geological sciences, and a California colleague reports that the two earthquakes in 1838 and 1890 occurred on the San Andreas Fault. Streig's research indicates that those quakes, like the better-known one in 1906, were surface-rupturing events.

The study is detailed in a news release, "San Francisco's 1906 quake was third of a series on San Andreas Fault."

- by Jim Barlow, Office of Strategic Communications