SCEC Award Number 26018 View PDF
Proposal Category Community Workshop
Proposal Title 2026 SCEC Workshop Proposal: Community Stress Drop Validation Project
Investigator(s)
Name Organization
Annemarie Baltay United States Geological Survey Rachel Abercrombie Boston University
SCEC Milestones C1,2,3-1, D1-1 SCEC Groups Seismology, FARM, SDOT
Report Due Date 09/19/2026 Date Report Submitted 09/10/2026
Project Abstract
 The Community Stress Drop Project is focused on understanding the nature and causes of discrepancies in earthquake spectral stress drop, as well as where random and physical variability arises, and effectively disseminating these results towards more effective collaboration with key users of earthquake stress drop. The importance and timeliness of this work is evidenced by the large, global attendance (> 100 people from 7 continents) at virtual workshops, regular attendance at informal zoom meetings, and engagement at smaller in-person workshops. Stage 1 of the Community Project began in 2021 with the Ridgecrest Study in which we distributed a common dataset to be analyzed by the community. The team spearheaded and guest edited a successful BSSA special issue on the topic with 46 included papers. The Community Stress Drop Validation Study was recently approved and funded by SCEC as a new Technical Activity Group in July 2026. This Phase II highlights three scientific objectives to 1) improve ground motion modeling; 2) benchmark new methods and datasets of spectral stress drop; and, 3) inform earthquake physics. This workshop, on August 20, 2026 held in person at the USGS Moffett Field, kicked off Phase II and focused on analyzing initial point-source synthetic data towards developing more complex synthetic datasets for verification, and determining a new empirical focus region for study.
Intellectual Merit The Community Stress Drop Project is focused on understanding the nature and causes of discrepancies in earthquake spectral stress drop. Spectral stress drop is a key parameter for understanding earthquake source physics as well as for ground motion modeling, and thus upholds SCEC priorities. One focus of the current workshop was to develop, analyze and iterate on synthetic datasets, but those that specifically are useful to the stress drop community, and consider how those types of synthetic data relate to other ongoing SCEC ground motion or rupture simulations.
Broader Impacts Through our broad global community, we have actively supported early career participants, always having students and postdocs engaged with the analysis and discussion aspects of the project as first authors. We have also worked towards effectively disseminating these results towards more effective collaboration with key users of earthquake stress drop. Out of 39 participants at this workshop, 11 were students and several were from outside of the direct field, which augmented the discussion topics in a positive way.
Project Participants At this workshop, there were 39 participants, with 7 online, one of whom was calling in from Korea. 11 participants were students and several others were early career. We distributed synthetic data, and 18 individuals, from students to emeritus, responded and analyzed the data, some of whom did not even attend the workshop. There was a strong desire from workshop participants and community members to keep the community engaged with these exercises and new empirical data.
Exemplary Figure Figure 2. Example earthquakes for the four sets of synthetic, point-source, stochastic spectral data. Each column is one dataset, generated by Annemarie Baltay (left column), Dino Bindi (second column), Chen Ji (third column) and Peter Shearer (right column). (Top row) Displacement spectra for an M4.78 earthquake and (middle row) M2.55, and (bottom row) the ratio between the two, with station distance in color. Note that for all but the Baltay data, there is no site-to-site variability and the ratios of the two earthquakes plot on top of each other for all stations.
Linked Publications

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