SCEC Award Number 25266 View PDF
Proposal Category Collaborative Research Project (Multiple Investigators / Institutions)
Proposal Title Determination of Shallow Crustal Structure in Northern California, the Bay Area, and Community Model Validation Using Rayleigh Wave Ellipticity, Receiver Functions, and Gravity
Investigator(s)
Name Organization
Fan-Chi Lin University of Utah Taka'aki Taira University of California, Berkeley
SCEC Milestones A1-1, A2-1, A3-6 SCEC Groups Seismology, CEM, GM
Report Due Date 03/15/2026 Date Report Submitted 05/08/2026
Project Abstract
 This proposed research is a continuation of PI Lin and Taira’s ongoing SCEC project entitled “Determination of Shallow Crustal Structure in Northern California and Community Model Validation Using Ambient-noise-derived Rayleigh Wave Ellipticity and Receiver Functions”, award number 24098. The goal of this study is to expand the previous analysis with broadband permanent network seismometers to strong-motion permanent network seismometers and other available temporary seismic array stations in northern California, the Bay Area in particular, targeting to improve the Community Seismic Velocity Model. We aim to make measurements of the ambient noise Rayleigh wave ellipticity (i.e., Rayleigh wave H/V) and teleseismic receiver function (RF) initial peak delay times, both of which have been proven to be quite sensitive to shallow sedimentary structure. We expect to have a significant increase in the data coverage by incorporating new strong motion and temporary array seismometers, especially in the densely populated San Francisco Bay Area and in Central Valley, where the velocity structure associated with the thick sediment remains poorly constrained. The seismic measurements will be directly compared with CVM predictions to validate the model. We will also compare our seismic measurements with the existing gravity measurements to investigate if an empirical relationship can be established. Since gravity is generally easier to survey with dense spatial sampling, establishing a seismic-gravity relationship could potentially improve the 3D regional velocity model where seismic measurements are limited.
SCEC Community Models Used Community Velocity Model (CVM)
Usage Description We validate the San Francisco Bay Area (SFBA) CVM using our seismic observations. We also compare our inverted models with the SFBA CVM.
Intellectual Merit We demonstrate that the SFBA CVM can be validated using Rayleigh-wave H/V ratios derived from multi-component ambient noise cross-correlations. We also show that incorporating these H/V measurements can improve shallow crustal models. These new models can be used to improve earthquake ground motion prediction.
Broader Impacts Improving the shallow crustal model can lead to more accurate ground-motion predictions and contribute to improved seismic hazard assessments in the San Francisco Bay Area. This project also provided valuable training for postdoc HyeJeong Kim and student Chi-Hsuan Wang in ambient noise cross-correlation, surface-wave analysis, and 1D MCMC inversion.
Project Participants Fan-Chi Lin, University of Utah (PI)
HyeJeong Kim, University of Utah (post-doc)
Chi-Hsuan Wang, University of Utah (visiting student)
Taka'aki Taira, Berkeley Seismo Lab (co-PI)
Exemplary Figure Figure 5. Comparison of inverted models and the SFBA CVM. (a–b) Inverted 1D Vs models at depths of 1 and 2 km; station symbols indicate the network (NP, NC, or BK). (c–d) SFBA CVM at depths of 1 and 2 km. Note that color scales differ between subplots. Credit: Fan-Chi Lin.
Linked Publications

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