SCEC Award Number 21059 View PDF
Proposal Category Individual Proposal (Data Gathering and Products)
Proposal Title Updating CVM-S 4.26 in Salton Trough Using Explosion Waveforms
Name Organization
Patricia Persaud Louisiana State University
Other Participants Rasheed Ajala (PhD Student), Alan Juarez (PhD Student; no-cost collaborator)
SCEC Priorities 4a, 3a, 2b SCEC Groups GM, SAFS, CXM
Report Due Date 03/15/2022 Date Report Submitted 01/01/2024
Project Abstract
The current proposal seeks to finalize our work in the SCEC5 research cycle by utilizing the Salton Seismic Imaging Project (SSIP) active source waveforms in full waveform inversion to update the current best Earth model in Salton Trough. The project will benefit from tools developed in our previous SCEC-funded projects and fully automated full-waveform inversion software available in the seismology community. Ajala & Persaud (2021) showed that embedding 3D travel time basin models for the Imperial Valley (Persaud et al., 2016) and Coachella Valley (Ajala et al., 2019) developed using SSIP active source data improves the waveform prediction ability of SCEC community models at low frequency. Here, we extend previous results by exploring other hybrid models generated using 13 sets of embedding parameters – and summarize their effect on waveform predictions up to a minimum period of 2 s. To evaluate our models, we check ground-motion predictions from the hybrid models against the pure regional models. We compare all model predictions to 3-component ground displacement records from five moderate magnitude earthquakes filtered in 2-30 s, 3-30 s, and 6-30 s bands with signal-to-noise ratio ≥ 3.
Intellectual Merit Our algorithm and basin-scale models used to improve the SCEC CVMs have been made available to the UCVM developers for use by the research community. The algorithm and all models including the hybrid models are also available in two publications (Ajala & Persaud, 2021; Ajala & Persaud, 2022). In addition, our detailed explorations of two standard SCEC Community Models and the influence of topography, geotechnical layer, and attenuation on wavefield predictions are available in Ajala, Persaud & Juarez (2022). Insights from these initial efforts have motivated our future research to further improve the hybrid models using SSIP data.
Broader Impacts This project involved one PhD student and an early-career faculty. The results from this research have been used in several presentations and lectures given by the PI. The algorithm and methodology provide a low-cost way to improve earthquake ground motion estimates and produce integrated Statewide Community Models for geological, geodynamic and earthquake studies. Our algorithm and the Salton Trough study will benefit other high seismic hazard regions particularly those located above sedimentary basins.
Exemplary Figure Figure 3 - S wave velocity maps at 2 km depth from the hybrid cvmh models with data (black) and synthetic (red) 6-30 s seismograms at some stations for events 5 and 3 (black stars). N-S components are shown for the hybrid and pure cvmh. The top-right label shows the percentage misfit change relative to the original SCEC CVM model for the three frequency bands (2-30 s, 3-30 s, and 6-30 s). Blending maps used to generate the models are shown in Fig. 2.