SCEC Award Number 18203 View PDF
Proposal Category Workshop Proposal
Proposal Title Integrated Science Workshop and Fieldtrip for the Cajon Pass Earthquake Gate Area
Investigator(s)
Name Organization
Julian Lozos California State University, Northridge Nate Onderdonk California State University, Long Beach Craig Nicholson University of California, Santa Barbara
Other Participants 35 field trip participants (TBD)
50 half-day meeting participants (TBD)
SCEC Priorities 1a, 2e, 3a SCEC Groups Geology, EFP, SAFS
Report Due Date 10/10/2018 Date Report Submitted 10/10/2018
Project Abstract
 The SCEC Earthquake Gate Area (EGA) Initiative is focused on the many factors that can conditionally halt or pass earthquake ruptures, and thus have control on the probability of large, multi-segment or multi-fault earthquakes. Cajon Pass was designated as the initial site for this focused EGA research because several major fault systems, including the San Andreas, northern San Jacinto and major reverse faults of the Transverse Ranges merge and intersect in this area. How these faults interact or modulate each other may strongly influence the propagation of earthquake ruptures through this region — a region with uniquely high seismic hazard potential to a number of critical lifelines and large urban populations. With these factors in mind, and given that an preliminary Cajon Pass EGA Science Plan had been developed already, the principal goals of the Cajon Pass EGA workshop were to: 1) help introduce the concepts of an earthquake gate and specifically the Cajon Pass EGA to a wider SCEC audience and to increase participation in Cajon Pass EGA research; 2) develop viable research strategies to help implement the major elements of the existing science plan; 3) help establish stronger coordination and collaborations between Cajon Pass EGA research activities; and 4) refine how the EGA science plan can help move forward SCEC’s research priorities during SCEC5.

Intellectual Merit The primary purpose of the workshop was to introduce, promote and advance the concepts and characteristics of Earthquake Gates, and specifically the features and research objectives of the Cajon Pass Earthquake Gate Area (EGA) Initiative to a wider SCEC audience. The Earthquake Gate concept and the Cajon Pass EGA Initiative have been designated as two primary research priorities in SCEC5. The combined field trip and workshop were able to advance our understanding of the current status, newly implemented funded EGA activities, and the promising areas for future investigations into Cajon Pass EGA Initiative research.
Broader Impacts As stated, there are many reasons why Cajon Pass was designated as the initial site for focused EGA research in southern California. The Cajon Pass area is the site where several major fault systems, including the San Andreas fault, northern San Jacinto fault and major reverse faults of the Transverse Ranges all merge and intersect, and it is how these faults interact or modulate each other that may strongly influence the propagation of earthquake ruptures through this region. Because of its location and potential controls on large earthquake ruptures associated with the San Andreas and San Jacinto faults, this region represents a uniquely high seismic hazard potential to a number of critical lifelines and large urban populations. Understanding this hazard and mitigating the risk will thus require a fundamental understanding of how the Cajon Pass EGA may influence this earthquake rupture behavior. The workshop and field trip were able to introduce the concepts of earthquake gates and the many important aspects of the Cajon Pass EGA Initiative and its research objectives to a wider SCEC audience that included many students and early-career scientists. Individuals from 35 different institutions, 10 States and six countries participated in the program.
Exemplary Figure Figure 2. Drone photo (courtesy of Art Sylvester) looking North across the San Andreas fault at Lost Lake showing the Lost Lake sag pond, fault scarps, and various terrace risers that were used as piercing lines for determination of slip-rate [Weldon and Sieh, 1985]. This photo exemplifies the potential for evaluating possible piercing points along the San Andreas fault and the difficulty of working in the complex topography and geology of Cajon Pass