SCEC Award Number 18169 View PDF
Proposal Category Collaborative Proposal (Integration and Theory)
Proposal Title Multi-fault rupture scenarios in the Brawley Seismic Zone: the effects of cross-faults and material heterogeneity on rupture initiation and termination
Investigator(s)
Name Organization
Christodoulos Kyriakopoulos University of California, Riverside David Oglesby University of California, Riverside Thomas Rockwell San Diego State University Aron Meltzner Nanyang Technological University (Singapore)
Other Participants
SCEC Priorities 4a, 1e, 1d SCEC Groups FARM, SAFS, Seismology
Report Due Date 04/30/2020 Date Report Submitted 07/20/2020
Project Abstract
 In the most recent and previously SCEC funded work, we performed dynamic rupture simulations of multi-fault systems that include the simultaneous activation of large structures such as the Southern San Andreas (SSAF) and the Imperial (IF) faults, but also a network of nearly perpendicular cross-faults (CF). We investigated scenarios of earthquakes nucleating on the main structures (SSAF and IF) and also cases with earthquake nucleation on the cross faults. In the first case our focus is on the possibility of large ruptures to propagate through the Brawley Seismic Zone while in the second case we are specifically interested on medium size (swarm type) earthquakes and their ability to trigger a major event on the SSAF. In our recent work (this SCEC grant) we focused on the effects that stress and material heterogeneities have on the two above cases. We found that the initial stress conditions can determine on which segment of the bifurcation the rupture will propagate (regardless of geometric continuity) and that the presence of layering did not affected previously investigated CF-SSAF triggering scenarios .
Intellectual Merit This research project explores the rupture dynamics and interaction of a multi-fault system that includes the Southern San Andreas (south of Coachella), the Imperial Fault, and the cross-faults in the Brawley Seismic Zone.
Broader Impacts This project and previously funded SCEC projects on the same topic have become the basis for a new education and outreach program based on Virtual Reality (VR).
The VR activity gives the possibility to non-experts ("the public") to visualize the complex system of faults in California as well as dynamic rupture experiments in a totally new perspective. The VR activity is used at both UC Riverside and the University of Memphis outreach programs.
Exemplary Figure Figure 4.

Final slip distribution for models with heterogeneous initial stress. A) Model N2S-RST-d20km; B) model N2S-RST-d15km; C) model S2N-RST-d20km; D) model S2N-RST-d15km. The black arrows indicate the north and east directions. The red continuous line highlights the Salton Sea shoreline while the yellow line indicates the US-Mexico border. View is approximately west towards east.