SCEC Award Number 25134 View PDF
Proposal Category Community Workshop
Proposal Title Community Stress Drop Validation Project 2025 Workshops
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 02/19/2026 Date Report Submitted 03/12/2026
Project Abstract
 The Community Stress Drop Validation Study has built a global community of researchers focused on understanding the physical controls and methodological reasons for similarity or differences in stress drops and other source characterization parameters, to enable more reliable use by the earthquake science community. Over the past four years, over 20 research groups have submitted stress drop estimates from the 2019 Ridgecrest Sequence common dataset, and many more have participated in analysis, workshops and community building, including the recent 2024 in-person early career workshop, with hands-on demonstration of different methods for estimating stress drops. The group has also spearheaded a BSSA special issue on Improving Measurements of Earthquake Source Parameters. So far, we have demonstrated and quantified the uncertainties in methodological biases in stress drop estimates, and their possible magnitude and depth dependencies. The next step is for the community to investigate and test improved approaches and address the remaining unanswered questions. In 2025, we plan to use a synthetic dataset, in coordination with other SCEC researchers. We will attempt to make a connection between the input stress drop used to generate these simulations, and the spectral stress drops that this group estimates. We will also investigate alternative ways to measure and characterize the frequency content of earthquake radiation that could potentially complement or improve on the traditional spectral stress drop approaches. To that end, we propose two workshops in 2025: one in-person at the SCEC Annual Meeting in Fall 2025, and a virtual workshop in January 2026, as in other years.
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 to (1) advance understanding of earthquake source physics and rupture processes, and (2) improve ground motion modeling and hazard assessment. We have brought together a global community to understand where random and physical variability arises in various stress drop methods, and have been very successful at generating dialog and comparing results, including through the recent BSSA special issue.
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. We always try to accommodate different global schedules in our workshops and meet ups, as witnessed by the afternoon recap session for people joining from eastern time zones.
Project Participants At this workshop, 132 participants attended, from 27 countries. Many of these folks have been deeply involved with the Community Stress Drop project, including students, postdocs and early career through emeritus researchers. At this particular workshop, we featured talks from five early career researchers including three postdocs: Gian Maria Boscchini (Ruhr University Bochum), Sara Beth Cebry (USGS) and Hilary Chang (Columbia); and two early career researchers: Mariano Supino (INGV) and Keisuke Yoshida (Tohoku University), all from around the globe.
Exemplary Figure Cover Figure: (a) Corner frequency and (b) study recalculated spectral Δσ averaged in discrete moment bins from many of the 56 submitted results from the first round of the Community Study, to show systematic offsets and trends in larger studies. Note that there are distinctly different trends and offsets between different methods and submissions. The dashed lines in panel (a) show constant stress drop trends for P and S waves. From Abercrombie, Baltay et al. (2025).
Linked Publications

Add missing publication or edit citation shown. Enter the SCEC project ID to link publication.