SCEC Award Number 23170 View PDF
Proposal Category Collaborative Proposal (Integration and Theory)
Proposal Title Damage zone of the Coachella Valley segment of the San Andreas Fault: Evidence of a moment-dependent bifurcation in off fault energy dissipation processes?
Investigator(s)
Name Organization
William Griffith Ohio State University Thomas Rockwell San Diego State University
Other Participants
SCEC Priorities 3d, 3c, 3e SCEC Groups FARM, Geology, SDOT
Report Due Date 03/15/2024 Date Report Submitted 11/12/2024
Project Abstract
 i. We proposed to continue the research started under Award # 22116 by conducting a full suite of additional microstructural and geochemical analyses on the 45 samples collected during fieldwork in 2022.
ii. We described 23 oriented sections and placed them in the context of the overall transect across the San Andreas fault at Ferrum. This work collectively allows us to document composition and deformation mechanisms, study partitioning between shear and volumetric deformation, and discriminate between various damage zone formation mechanisms (e.g., Mitchell and Faulkner, 2009; Frost et al., 2008; Rowe and Griffith, 2015).
iii. XRD analysis were be performed on select non-oriented samples following methods described in Wechsler et al. (2011) to determine bulk rock chemistry and mineralogy, respectively. Results of XRD analysis aid in discrimination between alteration products related to weathering vs deformation processes.
iv. We have also a NSF-UKNERC proposal in August based on SCEC-funded research during the past three years.
v. This project supported the research leading to the MS thesis of Aidan Fullriede (MS, 2024). The complete methods, results, and discussion can be found in his publically available thesis, listed in the references of this report.
Intellectual Merit The project provides constraints on the structure of the southern San Andreas Fault at Ferrum, a location where shallow transient creep co-exists with M~7.4 earthquake ruptures. We characterized the structure and mineralogy, and we also identified structures that we argue are uniquely coseismic, providing a glimpse into the near-field physics of earthquake ruptures there, while also providing the basis for future mechanical studies of the fault materials.
Broader Impacts This grant supported research leading to the MS degree (2024) of Aidan Fullriede.
Exemplary Figure Figure 4
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