SEISMIC HAZARD: CREEP AND PALEOEARTHQUAKES ON BAY AREA FAULTS

The San Andreas Fault system comprises five major branches in northern California. Many sections of these faults creep or slip slowly near the surface releasing some of their energy as creep. Decades of creep observations let us model how much energy is being stored elastically on these fault sections. Geological evidence for the timing of prehistoric earthquakes provides insight as to which of these faults have yet reached strain levels comparable to those released in past large (M≥6.7) earthquakes. Four urban creeping faults appear to be strained sufficiently for failure: the Green Valley, Rodgers Creek, Hayward and Northern Calaveras.

Jim Lienkaemper has been a research geophysicist/geologist at the U.S. Geological Survey in Menlo Park for the past 37 years, primarily specialized in investigation of active faulting in the San Andreas Fault system in California. He has focused on observation and modeling of fault creep, afterslip and the documentation of geological evidence of paleoearthquakes on creeping fault sections.