SCEC Award Number 16084 View PDF
Proposal Category Collaborative Proposal (Data Gathering and Products)
Proposal Title CERRO PRIETO-SAN JACINTO FAULT ZONE: MISSING SLIP DISCOVERED NEAR US-MEXICO BORDER
Investigator(s)
Name Organization
Phillip Hogan Fugro Consultants, Inc. Thomas Rockwell San Diego State University Scott Lindvall Lettis Consultants International, Inc.
Other Participants Mark Zellman (GIS), Jason Holmberg (Graphics)
SCEC Priorities 2a, 4a, 4b SCEC Groups WGCEP, FARM, Geology
Report Due Date 03/15/2017 Date Report Submitted 03/20/2017
Project Abstract
 We have compiled existing data, drafted trench logs to publication quality, and performed analysis of data including correlation of stratigraphy to nearby trench sites. Based on upward terminations of faults and liquefaction features in the Mexicali trenches, we have identified four events, and are evaluating evidence for a possible fifth event. These trenches document the northern extension of the Cerro Prieto fault, which apparently, steps slip to the southern extension of the Superstition Mountain fault across a broad zone of distributed faulting and liquefaction. Evidence for similar distributed faulting, ground failure, and liquefaction blows was observed across the Colorado Delta Domain during the 2010 El Mayor-Cucapah Mw 7.2 rupture (Fletcher et al., 2014).
Intellectual Merit Distributed faulting and liquefaction appears to have affected a broad region in a stepover zone between the northern extension of the Cerro Prieto fault and the southern extension of the Superstition Mountain fault. We have identified four events defined by upward terminations of faults and liquefaction features, and are evaluating evidence for a possible fifth event. Three of these events have displacement associated with them, which argues that they represent earthquakes on this fault strand. Slip rates on the CPSJ connector remain uncertain given the lack of measured offsets in the AEP trenches. However, we plan to publish the results of the current investigation in a peer-reviewed journal, and use this as a springboard for targeting future trench sites north and south of the international border that hold the potential for constraining slip rates and the associated seismic hazard posed by this important fault zone.
Broader Impacts This investigation is meaningful because it could help solve the slip deficit across the Salton Trough at the latitude of the US Mexican Border. Additionally, this study further demonstrates the distributed nature of faulting in this region, and the potential for fault and rupture interaction. More importantly, the results could help improve public safety, particularly in the greater metropolitan Mexicali area and border zone region.
Exemplary Figure Figure 8. Schematic log of one trench wall exposure from the power plant study.