Summary

The Community Stress Drop Validation Study aims to understand and reduce uncertainties in estimated spectral stress drop and related source parameters, strengthening their use in empirical ground motion models and earthquake source representations in simulations. In Phase I, the community researchers evaluated existing approaches by estimating stress drop for the 2019 Ridgecrest earthquake sequence. Phase II of the study is designed to address problems exposed in Phase I applying evolving methods to synthetic data and a new empirical data set for the San Francisco Bay Area with an additional focus on seismic moments and magnitudes and site amplification and attenuation. The aim of this in-person workshop is to develop the design for the planned synthetic tests and begin analysis of the first synthetic data, together with selection of the optimal Bay Area empirical dataset. The format will be primarily discussion based.

To evaluate how effectively different methods can separate source, site, and path effects, identifying the effects of heterogeneity in each part, will require multiple, carefully designed synthetic experiments.. As a first step, we will distribute a small dataset of simple synthetic earthquake Fourier amplitude spectra for a community-scale test. Initial trials using these synthetics demonstrate that earthquake stress drop can be successfully inverted, producing interesting and informative trends while remaining easy to analyze because the data are complete and uniformly sampled.

All workshop attendees, and any additional interested participants, are invited (and encouraged!) to take part in this initial community effort. We will provide a small synthetic dataset of record spectra on approximately July 20, and we ask participants to return preliminary results for stress drop, magnitude, and/or site terms by August 14. These results will be discussed at the workshop, where we will also develop plans for the next, larger phase of the synthetic experiment.

The workshop also aims to define the range and scope of the Bay Area empirical dataset. By incorporating feedback from researchers with broader scientific interests, we will ensure that our focus area aligns with and contributes to other SCEC and USGS research goals. We will further discuss future directions and leadership for additional thrusts of the proposed TAG, including efforts on seismic moment and magnitude, as well as modeling site attenuation and amplification.

An in-person poster session will enable participants to showcase and discuss ongoing work on stress drop and related topics. Participants are encouraged to bring a new or previously presented poster on any relevant theme. There will be plenty of time for networking and breakout discussions.

Who Should Apply. We welcome applications from, and aim to achieve a balanced representation of, participants from observational seismologists and engineers, rupture modelers, and lab-based geophysicists. We welcome those who have or want to analyze stress drop, and those who want to learn more about it, or are interested in supporting or leadership roles in the project. We also seek a balance across career stages, including graduate students, early-career researchers, and established investigators, to promote cross-generational exchange and collaboration. An in-person poster session will enable participants to showcase and discuss ongoing work on stress drop and related topics. Participants are encouraged to bring a new or previously presented poster on any relevant theme.

Travel Support

Applicants should complete the travel support section carefully as part of the application process. Students, early‑career researchers, and participants without institutional funding are especially encouraged to apply for travel support. Subject to available funding, SCEC travel support may include lodging arrangements on the campus at Moffett Field, and/or reimbursement of travel and meal expenses, up to available funding limits. Local travelers are encouraged to pursue carpooling. Please contact the organizers directly if you would like to attend but can only do so remotely. 

To foster discussion and interaction, the workshop is expected to convene approximately 50 participants, who will be selected based on their statement of interest and the potential contribution to the workshop objectives.