Seismic Traveltime Tomography of Southern California Using Poisson‐Voronoi Cells and 20 Years of Data
Name
JGR Solid Earth - 2022 - Fang - Seismic Traveltime Tomography of Southern California Using Poisson‐Voronoi Cells and 20.pdf
Description
Published version
Size
5.58 MB
Format
Adobe PDF
Checksum (MD5)
3facb47eb0a69829da5a2a91390d6cdc
Author(s)
Fang, Hongjian
White, Malcolm CA
Lu, Yang
Ben‐Zion, Yehuda
Date Issued
April 26, 2022
Journal
Journal of Geophysical Research: Solid Earth
Publisher
American Geophysical Union
Version
Final published version
Abstract
We derive new, 3D, isotropic models of seismic compressional and shear wavespeeds, Vp and
Vs, respectively, their ratio, Vp/Vs, and a catalog of relocated earthquakes for Southern California from more
than 10 million P- and S-wave arrivals associated with over 0.3 million earthquakes that occurred between
2000 and 2020. We augment high-quality analyst-reviewed phase arrival picks from the Southern California
Earthquake Data Center with S-wave arrival picks obtained with an automated algorithm, and we derive new
wavespeed models via traveltime tomography formulated using Poisson-Voronoi cells (Fang et al., 2020, https://
doi.org/10.1785/0220190141). The results contribute to improved regional wavespeed models, particularly
the Vp/Vs model, and absolute event locations. The obtained models correlate well with regional geological
features and yield more accurate synthetic waveforms than other regional models do for waves with periods
shorter than 5 s in much of the modeled region. The derived event catalog exhibits tighter spatial clustering than
the standard regional catalog, thereby helping to characterize subsurface features of major faults. The regional
1D averaged Vp/Vs ratio shows high values at shallow depths, decreases to a minimum at about 10 km, then
increases again at greater depths below 15 km. Deep seismicity correlates well with regions of Vp/Vs ratio
lower than 1.75, which may indicate an increased brittle-to-ductile transition depth with an important influence
on crustal mechanics. The new wavespeed models and seismic catalog can be useful for various studies
including analyses of seismicity patterns and simulations of crustal deformation and ground motion.
MIT Department
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
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Persistent DSpace Link
DOI of Published Version
https://doi.org/10.1029/2021JB023307
