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Dynamic rupture scenarios in the Brawley seismic zone, Salton Trough, southern California.

Christodoulos Kyriakopoulos, David D. Oglesby, Thomas K. Rockwell, Aron J. Meltzner, Michael Barall, John M. Fletcher, & Drew Tulanowski

Published February 19, 2019, SCEC Contribution #8889

In this paper we investigate the dynamic behavior of a system of interconnected faults in the Brawley Seismic Zone (BSZ) in southern California. The system of faults includes the southern San Andreas fault (SSAF), the Imperial fault (IF), and a set of cross-faults in the BSZ that may serve as connecting structures between the two larger faults. Geological and seismic evidence implies that the SSAF and IF may have buried extensions that link them together in a large-scale stepover, with the cross-faults in the BSZ cutting between them. Such a configuration poses the question of whether through-going rupture across the stepover is possible in this region, leading to large, plate-boundary scale earthquakes. We investigate potential earthquakes in this region through 3D dynamic finite element spontaneous rupture modeling. We find that under multiple assumptions about fault stress and fault geometry, through going rupture is possible, both from North to South and South to North. Participations of the cross-faults is facilitated by two factors: absence of rupture on one of the main two faults, and a contrast in pre-stress between the main faults and the cross-faults leading to a slower propagation speed on the main faults. The pattern of rupture propagation and slip is strongly affected by fault-to-fault dynamic stress interactions during the rupture process. The results may have implications for both potential earthquakes in this region, as well as for understanding the dynamics of geometrically complex/branched faults in general.

Kyriakopoulos, C., Oglesby, D. D., Rockwell, T. K., Meltzner, A. J., Barall, M., Fletcher, J. M., & Tulanowski, D. (2019). Dynamic rupture scenarios in the Brawley seismic zone, Salton Trough, southern California.. Journal of Geophysical Research, Solid Earth,.

Related Projects & Working Groups
Fault and Rupture Mechanics (FARM)