The Brawley Seismic Zone: Geologic, Seismic, and Dynamic Constraints on Possible Through-going Rupture Scenarios

Drew Tulanowski, Christodoulos Kyriakopoulos, Aron J. Meltzner, Thomas K. Rockwell, & David D. Oglesby

Published 2015, SCEC Contribution #7077

Seismicity in the Brawley Seismic Zone and the indistinguishable timing of large paleoseismic ruptures of the Imperial and southernmost San Andreas faults suggest that there is a possibility of through-going fault structures connecting the Imperial fault to the southern San Andreas fault. Using the Waveform Relocated Earthquake Catalog for Southern California from 1981 to 2011 (Hauksson et al., 2012), one can outline two general paths that a through-going fault might take if present. Using the 3D finite element method (Barall, 2009) and realistic fault geometry, we test if an earthquake rupturing on the Imperial Fault can travel along one or more of these possible through-going faults and allow slip to propagate to the San Andreas. We test the sensitivity of rupture propagation to nucleation location, determine which of the potential through-going structures is the more likely rupture path, and what the partitioning of slip might be in this system. In addition, the seismicity indicates a series of left-lateral cross fault structures that run through the Brawley Seismic Zone, possibly intersecting and connecting our two through-going fault structures. Future experiments will incorporate these cross faults and test how they play a role in this area. The results may have implications for seismic hazard not just in the Imperial Valley, but also throughout Southern California.

Citation
Tulanowski, D., Kyriakopoulos, C., Meltzner, A. J., Rockwell, T. K., & Oglesby, D. D. (2015). The Brawley Seismic Zone: Geologic, Seismic, and Dynamic Constraints on Possible Through-going Rupture Scenarios. Poster Presentation at 2015 SCEC Annual Meeting.