SCEC Award Number 22034 View PDF
Proposal Category Individual Proposal (Integration and Theory)
Proposal Title Coda-based Moment Magnitude and Stress Drop Measurements for the 2019 Ridgecrest Earthquake Sequence
Investigator(s)
Name Organization
Taka'aki Taira University of California, Berkeley Douglas Dreger University of California, Berkeley
Other Participants Kevin Mayeda (Air Force Technical Applications Center)
William Walter (Lawrence Livermore National Laboratory)
Rengin Gök (Lawrence Livermore National Laboratory)
Jorge Roman-Nieves (Air Force Technical Applications Center)
SCEC Priorities 1d, 1e, 3b SCEC Groups Seismology, FARM, GM
Report Due Date 03/15/2023 Date Report Submitted 12/04/2023
Project Abstract
 This project focuses on evaluating the stress drops of Ridgecrest earthquakes by using the coda envelope spectral ratio introduced by Mayeda et al. (2007) and Walter et al. (2017) to measure the moment magnitude (Mw), corner frequency, and stress drop through the recently developed Coda Calibration Tool (CCT) (Barno, 2017), and we performed rigorous comparisons of source parameters obtained from finite-source modeling with empirical Green’s function (eGf) (Dreger, 1997) to understand the effect of model assumptions and the selection thresholds of eGf events on stress drop measurements. We also included published works of the Ridgecrest stress drops (Bindi et al., 2021; Trugman, 2020) for our comparative analysis of resultant stress drop values.
Intellectual Merit We used four different methods: 1) Coda Calibration Tool (CCT), 2) finite-fault (FF) modeling, 3) Generalized Inversion Technique (GIT) from Dino Bindi, and 4) FSSE (Frequency Domain S-Wave Stress Estimation) from Chen Ji and Ralph Archuleta to compare source parameters obtained for Ridgecrest aftershocks with a wide range of magnitude (3.5 < M < 5.0). We find excellent agreement between all four approaches for common events
Broader Impacts This project was closely performed with the SCEC Community Stress Drop Validation Study group (Baltay et al, 2021) and we were participated in their regular virtual “zoom” meetings and we also presented our work in the virtual stress drop workshop. All our results are sheared with other colleagues through this community effort.
Exemplary Figure Figure 10 of the Technical Report. Figure caption (from the report): Source parameter comparison from four different approaches.