A maximum rupture model for the southern San Andreas and San Jacinto Faults California, derived from paleoseismic earthquake ages: observations and limitations

Katherine M. Scharer, & Doug Yule

Under Review June 11, 2020, SCEC Contribution #10105

Paleoseismic rupture histories provide spatio-temporal models of earthquake moment release needed to test numerical models and lengthen the limited instrumental catalogue. We develop a model of the fewest and thus largest magnitude earthquakes permitted by paleoseismic data for the last 1500 years on the southern San Andreas and San Jacinto faults, California USA. The largest geometric complexity appears to regulate the system: only two ruptures break the San Gorgonio Pass region, followed by episodes of contemporaneous ruptures that could bridge the northern San Jacinto fault and the San Andreas fault. When tested against independent data on slip per event, the model produces comparable values indicating the end-member model does not under-predict rupture rates. Rupture of >85% of the fault length in the historic period (18001857) and the subsequent quiescence is similar to epochs of activity in the prehistoric model, suggesting that regional clustering of seismicity could be a robust trait of the system.

Citation
Scharer, K. M., & Yule, D. (2020). A maximum rupture model for the southern San Andreas and San Jacinto Faults California, derived from paleoseismic earthquake ages: observations and limitations. Geophysical Research Letters, (under review).