SCEC Award Number 14077 View PDF
Proposal Category Collaborative Proposal (Integration and Theory)
Proposal Title Constraining critical fault structures and mechanics in the Imperial Valley, California using InSAR observed surface deformation
Investigator(s)
Name Organization
Elizabeth Madden University of Massachusetts Amherst Michele Cooke University of Massachusetts Amherst Mariana Eneva Imageair
Other Participants 1 Graduate Student
SCEC Priorities 4a, 4b, 4c SCEC Groups FARM, USR, SDOT
Report Due Date 10/31/2015 Date Report Submitted 11/17/2015
Project Abstract
 This project refined 3D fault geometries in the Imperial Valley, California using multicyle and interseismic mechanical models. Three structural interpretations of the Imperial Valley fault system are complete, representing increasing structural complexity. Mapped splay faults on the northern and southern ends of the Imperial Valley Fault improve fit to observed slip rates, though the multicycle model rates remain low, possibly due to incorrect strike of the Cerro Prie- to Fault in the CFM, which should transfer greater slip to the Imperial Fault. A short version of the Laguna Salada Fault from CFM5 performs better than both a longer structure that extends through recent seismicity and an alternative geometry that matches the complex surface fault- ing mapped following the El Mayor-Cucapah earthquake. The interseismic model has slip rates determined from the multicycle model along the refined model geometries. PI Madden men- tored Research Assistant Laura Fattaruso to complete these models, together with PI Cooke. The final model-ready mesh of the preferred fault structures will be contributed to the CFM and estimates of the tectonic stressing rate field will be contributed to the CSM.
Intellectual Merit The southern San Andreas Fault has a 59 % chance of hosting a M 6.7 or larger earthquake over the next 30 years [WGCEP, 2008]. The San Jacinto and Imperial faults have the next highest seismic hazard in California, with respective probabilities of 31 % and 27 % [WGCEP, 2008]. The proximity of these faults to one another within the Imperial Valley introduces the possibility that they could rupture together in a single, large earthquake, threatening the safety of those living in Los Angeles, Imperial, Riverside and San Bernardino counties. However, the 3D active fault structures in the Imperial Valley are not known well enough to evaluate the po- tential for such a multifault event. This work provides critical information required for determin- ing and mitigating seismic hazard in the region.
Broader Impacts Postdoctoral Researcher Betsy Madden mentored Research Assistant Laura Fattaruso on the modeling aspects of this project, which was a valuable experience for both. This allowed Mad- den to gain advising experience critical to advancing her geoscience career. The project also happens to be the result of collaboration between 4 women, who are traditionally underrepre- sented at the PI level in the geosciences. It is also a collaboration between academic research at the University of Massachusetts and research by the private company ImageAir, Inc.
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