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Update and Future Plans for the International SCEC/USGS Community Stress Drop Validation Study

Description: 

We present the results to date of the Statewide California Earthquake Center/U. S. Geological Survey Community Stress Drop Validation study. The Community study has engaged a wide international group since its conception in 2021, focused on using a common dataset of the 2019 Ridgecrest, California earthquake sequence. The aim of the collaboration is to improve the quality of stress drop and earthquake source parameter estimates and their uncertainties, to enable more reliable ground motion forecasting, and towards a better understanding of earthquake source physics.

To date, we have received 56 unique community submissions, consisting of spectral corner frequencies (or source durations), moment magnitudes, and spectral stress drops. Initial analysis reveals significant scatter of spectral stress drops spanning over six orders of magnitude. Averaging submissions for a prioritized subset of 56 events results in a minimal standard deviation between spectral stress drops, indicating overall consistency. Lack of correlation between methods for magnitudes less than ~2.5 indicates that obtaining reliable spectral stress drop values for events this small is difficult, at least within the frequency range of the data. We use submitted moments to study the relationship between seismic moment and both catalog local and moment magnitude to develop a consistent magnitude scale for comparison. Considering the trends in magnitude and depth for each set of submissions demonstrates consistent trade-offs. We examine the spatial and temporal distribution of averaged, de-trended values to investigate relationships with the M7.1 mainshock rupture.

The results to date will be published in the coming Special Issue of the SSA Bulletin. The next stage of the community endeavor will likely include an experiment involving synthetic data. We welcome new members to the study, wishing to observe, learn or more actively participate. Visit https://www.scec.org/research/stress-drop-validation for more information.

Session: Advances in Reliable Earthquake Source Parameter Estimation [Poster]

Type: Poster

Date: 4/16/2025

Presentation Time: 08:00 AM (local time)

Presenting Author: Rachel

Student Presenter: No

Invited Presentation: No

Poster Number: 22

Authors