SCEC Award Number 11165 View PDF
Proposal Category Collaborative Proposal (Integration and Theory)
Proposal Title Collaborative research: Rupture propagation and slip at complex fault intersections: The San Andreas-San Jacinto-Cucamonga fault intersection in Cajon Pass
Investigator(s)
Name Organization
David Oglesby University of California, Riverside James Dolan University of Southern California
Other Participants
SCEC Priorities A9, A10, B1 SCEC Groups FARM, Seismology
Report Due Date 02/29/2012 Date Report Submitted N/A
Project Abstract
 One of the most important goals in seismology is to provide realistic ground motion estimates for future earthquakes—preferably in a probabilistic sense that accounts for the possibility of multiple earthquake scenarios. In regions such as Southern California, where there is a network of complex interacting and intersecting faults, a key question is the likelihood of fault-to-fault rupture propagation, which would in principle lead to larger earthquakes than slip on single fault segments. The geometry of fault intersections also has a profound influence on the slip pattern and rupture timing, and thus on the details of ground motion. While paleoseismological evidence can help place limits on possible rupture lengths, currently dynamic earthquake models are the only way that we can place physics-based constraints on all aspects of rupture behavior at fault intersections. In 2011, David Oglesby (UCR), James Dolan (USC), and SCEC Intern Bryan Gulotta (Haverford College) began a project to use the SCEC Community Fault Model (CFM) to construct realistic 3D models of Southern California fault systems, and then perform dynamic rupture model calculations for scenario earthquakes. Our 2011 project is the starting point of a multi-year research program; in this first year, we have been working on an interface between the SCEC CFM and a 3D dynamic finite element code (Barall, 2009). Our first test case is the intersection of the San Andreas, San Jacinto, and Cucamonga faults near Cajon Pass, north of San Bernardino, California (Figure 1). While we have not completed this project, we have made very good progress, and work will be ongoing throughout 2012. The results of this work will have an immediate impact on estimation of fault-to-fault rupture probabilities amongst these three major faults, as well as scenario ground motions for seismic hazard analysis and Next-Generation Attenuation Relations; in the longer term it may lead to better real-time forecasting of rupture behavior, damage, and emergency response.
Intellectual Merit This work will pertain directly to a number of SCEC’s short-term goals, including A9 (Assess predictability of rupture extent and direction on major faults), A10 (Develop statistical descriptions of heterogeneities (e.g., in stress, strain, geometry, and material properties), and understand their origin and implications for seismic hazard by observing and modeling single earthquake ruptures and multiple earthquake cycles, and B1 (Develop kinematic and dynamic rupture representations consistent with seismic, geodetic, and geologic observations.
Broader Impacts The proposed work will have strong implications for seismic hazard and ground motion estimation in Southern California. This was the project of a SCEC intern, Bryan Gulotta.
Exemplary Figure Figure 3. Fault geometry (a) and finite element mesh from CUBIT (b) for intersection of San Andreas, San Jacinto, and Cucamonga faults in Cajon Pass.