Ground-Motion Predictions for Salton Trough Using Cross-Pollinated Earth Models

Patricia Persaud, & Rasheed Ajala

Published September 11, 2022, SCEC Contribution #11955, 2022 SCEC Annual Meeting Poster #215

Strategies for improving Earth models to better predict the seismic wavefield are an active research topic in earthquake hazard studies. Such models should include realistic representations of fault zones, sedimentary basins, and other small-scale geological structures that are often poorly imaged in regional velocity models but well resolved in local velocity models. The recently developed Earth model hybridization technique smoothly merges Earth models of any shape, is cost-effective, and shows promise in improving models used in deterministic earthquake hazard evaluation. Here, we augment the results of Ajala and Persaud (2021) by exploring other hybrid models for Salton Trough generated using 13 sets of merging parameters—taper widths and subvolumes—and summarize their effect on waveform predictions up to a minimum period of 2 s. Our results introduce the notion of compatibility as a consideration by showing that the same basin models embedded into two different regional models can produce notably different outcomes. In contrast to most of our hybrid Harvard models that produce better matching ground motions, only one of the hybrid models generated using the Southern California Earthquake Center model as a regional model gives a closer match to the waveforms. Similar results are obtained at higher frequencies; however, improvements due to hybridization are reduced. A potential explanation for these results may be the limited high spatial frequencies in the travel time tomography basin models and the >5–6 s wavefield-dominated adjoint regional models. Although the strongly tapered compatible hybrid models tend to produce better results, we find instances of improvements even with merging artifacts.

Key Words
Waveform Prediction, Ground Motions, Model Validation, Salton Trough, San Andreas Fault, Community Models

Citation
Persaud, P., & Ajala, R. (2022, 09). Ground-Motion Predictions for Salton Trough Using Cross-Pollinated Earth Models. Poster Presentation at 2022 SCEC Annual Meeting.

Related Projects & Working Groups
Ground Motions