SCEC Award Number 20056 View PDF
Proposal Category Workshop Proposal
Proposal Title Science Workshop for the Cajon Pass Earthquake Gate Area
Investigator(s)
Name Organization
Nate Onderdonk California State University, Long Beach Julian Lozos California State University, Northridge Craig Nicholson University of California, Santa Barbara
Other Participants
SCEC Priorities 1a, 2e, 3a SCEC Groups SAFS, Geology, FARM
Report Due Date 03/15/2021 Date Report Submitted 10/05/2020
Project Abstract
 SCEC defines Earthquake Gate Areas (EGA) as “regions of fault complexity conjectured to inhibit propagating ruptures, owing to dynamic conditions setup by proximal fault geometry, local material properties, distributed deformation, and earthquake history." The four primary science questions related to EGAs are:
1. How do fault intersections affect the probability of through-going earthquake ruptures?
2. How does 3D fault geometry and stress variations modulate these through-going rupture probabilities?
3. How do prior ruptures affect future rupture paths and probabilities?
4. Does the current stress field reflect recent rupture history or is it more influenced by other factors?
The purpose of this workshop was to present and discuss ongoing research in the Cajon Pass EGA, to solicit and encourage additional studies and new investigators, and to establish science priorities for the remainder of SCEC5 and beyond. 2020 is the beginning of the fourth year of SCEC5, but only the third year of the Cajon Pass Earthquake Gate initiative. Numerous projects have been funded to address the Cajon Pass EGA science plan. This workshop brought various Cajon Pass investigators together to assess what progress had been made since the first Cajon Pass workshop in 2018, and what still remained to be done.
Intellectual Merit This workshop contributed to the overall SCEC goals by facilitating collaboration between SCEC scientists focused on better understanding the southern California fault system. The exchange of ideas and planning for future work will contribute to advancements in basic SCEC questions. For example, 1) recent and continued earthquake geology work will help answer "How are faults loaded across termporal and spatial scales?", 2) ongoing modeling is working to explain "How strong ground motions depend on the complexities and nonlinearities of dynamic earthquake systems?", and 3) the synthesis of geologic, geophysical and modeling studies are demonstrating "How system-specific studies can enhance the general understanding of earthquake predictability".
Broader Impacts This workshop promoted teaching, training, and learning at multiple institutions by providing the opportunity for graduate students (both PhD and MS) to present their research and to participate in discussions about their work and their peers'. Several of the presentations were made by traditionally under-represented groups in the geosciences, and numerous scientists that fall into this framework participated in the workshop. The result of this workshop and the associated projects, will benefit society in the form of increase understanding of earthquake hazards in the Cajon Pass area and the larger southern California region. The participation of scientists from various government agencies helped facilitate the dissemination of new results and interpretations to the broader public.
Exemplary Figure Figure 2. Rupture model for 1812 earthquake that bridges the gap between SAF and SJF, and triggers observed, characteristic normal slip on the intervening ‘passenger’ LCRF (Rodriguez Padilla et al., 2019). Color bars indicate amounts of right-slip on SAF & SJF, and normal-slip on LCRF, respectively.
Linked Publications

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