Using Dynamic Rupture Simulations to Explore Fault Segmentation and Rupture Length on the Sierra Madre Fault Zone

The Sierra Madre Fault Zone (SMFZ) is a 125 km-long, north to northeast-dipping thrust fault which arcs along the southern edge of the San Gabriel and Santa Susana Mountains in Los Angeles and San Bernardino counties, southern California. Based on its length alone, it is capable of producing a ~M7.7 earthquake, but its discontinuous geometry may lead to it rupturing in multiple smaller (~M6-M7) events (such as the M6.6 1971 San Fernando earthquake). Given the SMFZ?s location through the densely-populated San Fernando, San Gabriel, and San Bernardino valleys, even a smaller earthquake on this fault would have major implications for human safety and infrastructure stability. We will conduct 3D dynamic rupture simulations on the SMFZ, which we will parameterize with four major segments (from east to west: the Cucamonga Fault, the eastern and western Sierra Madre Fault, and the San Fernando Fault), to assess plausible rupture behaviors and ground motion distributions for this fault system. We will use SCEC CFM fault geometry, SCEC CVM surrounding rheology, and SCEC CSM regional stress orientations to ensure that our model setup is grounded in observation and that our results are realistic.