SCEC Award Number 25246 View PDF
Proposal Category Community Workshop
Proposal Title Earthquake rupture and creep in shallow earth materials
Investigator(s)
Name Organization
William Griffith Ohio State University Katherine Scharer United States Geological Survey Alexis Ault Utah State University
SCEC Milestones A1-3, A2-2, B1-1, B3-3, C2-1, D1-1 SCEC Groups Geology, Geodesy, FARM
Report Due Date 12/13/2025 Date Report Submitted 02/05/2026
Project Abstract
 We led a two-day, in-person workshop with scientists from across the full spectrum of Statewide California Earthquake Center (SCEC) disciplines to explore earthquake rupture and creep in shallow earth materials, and to discuss technologies and strategies for studying these processes through future observations and implementing them in modeling efforts. The workshop included a one-day field trip to visit three sites along the Southern San Andreas Fault (SSAF) at the Salt Creek paleoseismic site, Ferrum, and the Mecca Hills, CA (Fig. 1), followed by one day of presentations and moderated discussions in Palm Springs, with emphasis placed on involvement of early career researchers.

Shallow on- and off-fault earth materials are part of the geotechnical layer that can influence deformation throughout the earthquake cycle and strong ground motion. Key workshop topics were (1) geodetic and geomorphic observations of shallow crustal deformation associated with earthquake rupture and interseismic creep, (2) geological processes associated with this deformation, (3) the properties of the geotechnical layer that cause uncertainties in modeling seismic site response and the interpretation of surface deformation observations, and (4) strategies for future instrumentation and observations needed to resolve uncertainties, as well as identifying key study areas outside of southern California in the statewide center.
SCEC Community Models Used Community Rheology Model (CRM), Community Fault Model (CFM), Community Velocity Model (CVM), Community Geodetic Model (CGM)
Usage Description Discussions focused primarily on the Community Rheology Model, specifically what shallow earth properties should be represented and how.
Intellectual Merit Direct observations of earthquakes and creep on active faults are limited to Earth’s surface through the geotechnical layer, a shallow (tens to hundreds of meters thick) zone of rock, sediment, and soil that is generally weaker than the crystalline bedrock below. Geodetic and geologic observations illustrate a spectrum of faulting processes that occur in the geotechnical layer. What mechanical, fluid-mediated, and strain rate-dependent processes control these behaviors? How are these processes preserved as permanent deformation in fault zone structure? These questions are critical to interpreting geodetic observations of deformation, paleoseismic records of earthquake history, and for predicting future hazards.
Broader Impacts Over half of the workshop participants were early career researchers, including scientists that are new to the SCEC community. An outcome of this workshop is the identification of synergies between researchers across career stages and disciplines that have the potential to catalyze future SCEC-related research. Importantly, we have already proposed a Technical Activity Group focused on identifying the key multidisciplinary problems in the geotechnical layer to guide future SCEC-related earthquake science. Outcomes will also be presented by the organizers at the 2026 SCEC Annual Meeting.
Project Participants This was a two part workshop, including a 1 day field trip and a 1 day science meeting. The field trip was led by Alexis Ault, Tom Rockwell, Ashley Griffith, and Kate Scharer. The science meeting was led by Ashley Griffith, Alexis Ault, and Kate Scharer. There were 37 meeting participants. All are listed in the project report.
Exemplary Figure There are no figures in this workshop report.
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