SCEC Award Number 25198 View PDF
Proposal Category Individual Research Project (Single Investigator / Institution)
Proposal Title Investigating Along-Fault Variation of Shallow Inelastic Damage of the San Andreas Fault
Investigator(s)
Name Organization
Folarin Kolawole Columbia University
SCEC Milestones A3-6 SCEC Groups FARM, CEM
Report Due Date 03/15/2026 Date Report Submitted 10/04/2026
Project Abstract
 A recurring question in modern seismic hazards of active plate boundary systems is on the along-strike variability of long-term inelastic damage along their principal fault zones, and how this variability influences shallow fault zone rheology, yield strength of fault blocks, and near-field coseismic ground shaking. Along the San Andreas Fault (SAF), decades of field geological mapping and seismological characterization have advanced the understanding of many important segments of the plate boundary, yet there remains a knowledge gap on the detailed relative variation in the shallow rheology along-strike of the fault zone as viewed through the lens of coupled field geology and shallow geophysical imaging. Our proposed project aims to bridge this gap by leveraging on published field geological and/or geophysical characterization of exposures of the principal slip zone of the Mohave segment of the SAF (MSAF), by conducting shallow (<100-m deep) high resolution seismic survey experiments across sites that are yet to be seismically imaged but are geologically characterized and utilize both techniques in segments that lack both forms of characterization. We will estimate the on- and off-fault shear modulus of the slip zone at each site and eventually, compare how fault damage structure maps onto the shear rigidity estimates to assess the first-order along-fault variability in the rheology of the SAF. We anticipate that the results of this project will provide realistic fault zone rheology constraints that can improve SCEC's computational dynamic rupture simulations to accurately capture the expected near-fault coseismic ground shaking effects along the MSAF.
SCEC Community Models Used Community Fault Model (CFM)
Usage Description We utilized the Community Fault Model (CFM) to guide the field mapping of damage zones of the San Andreas Fault within the region of focus of our study.
Intellectual Merit We have identified and mapped the detailed deformation patterns in granitic country rocks proximal to- and distal to the modern SAF trace at Lake Elizabeth. The results demonstrate that the pulverized nature of the granites diminishes with distance from the modern SAF trace. A well-developed but inactive SAF-parallel fault core at distance from the modern fault trace documents earlier deformation in the SAF wall rocks. We also document heterogeneity of fault rock lithologies within the pulverized granites. Overall, the observations are relevant for understanding long-term off-fault deformation in granitic wall rocks of active continental transform faults such as the SAF.
Broader Impacts The project supported the undergraduate thesis research of Columbia undergraduate student Maya Madajewicz by providing funds for a field season in the Elizabeth Lake area of Southern California in Winter 2026. The student is currently analyzing the datasets and will be writing the results up into her bachelor’s thesis as well as a short journal article for future submission. Through this project and the training, she is receiving, Maya has been motivated to continue her career to PhD level. Thus, the project is helping to maintain a pipeline for the retention of talented undergraduate women in academic research.
Project Participants The individuals that are involved in the project include: 1) Columbia University students: Maya Madajewicz (undergraduate student) and Meritxell Colet (PhD student), 2) Kelian Dascher-Cousineau (collaborator, Utah State University), and 3) Rufus Catchings (collaborator, USGS).
Exemplary Figure Figure 1. Field photograph taken during the geological field mapping work along the Lake Hughes - Elizabeth Lake sections of the MSAF. (a – b) Maya Madajewicz (undergraduate student) and Meritxell Colet (PhD student) mapping the deformation of the SAF wall rocks. (c - d) Exposure of a 1-1.5 m wide SAF-parallel fault core at ~600 m NW of the Q-Fault surface trace of the SAF.
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