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Stress- and structure-induced anisotropy in Southern California from two-decades of shear-wave splitting measurements

Li, Zefeng and Peng, Zhigang (2017) Stress- and structure-induced anisotropy in Southern California from two-decades of shear-wave splitting measurements. Geophysical Research Letters, 44 (19). pp. 9607-9614. ISSN 0094-8276. https://resolver.caltech.edu/CaltechAUTHORS:20170918-155840650

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Abstract

We measure shear wave splitting (SWS) parameters (i.e., fast direction and delay time) using 330,000 local earthquakes recorded by more than 400 stations of the Southern California Seismic Network (1995–2014). The resulting 232,000 SWS measurements (90,000 high-quality ones) provide a uniform and comprehensive database of local SWS measurements in Southern California. The fast directions at many stations are consistent with regional maximum compressional stress σ_(Hmax). However, several regions show clear deviations from the σ_(Hmax) directions. These include linear sections along the San Andreas Fault and the Santa Ynez Fault, geological blocks NW to the Los Angeles Basin, regions around the San Jacinto Fault, the Peninsular Ranges near San Diego, and the Coso volcanic field. These complex patterns show that regional stresses and active faults cannot adequately explain the upper crustal anisotropy in Southern California. Other types of local structures, such as local rock types or tectonic features, also play significant roles.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1002/2017GL075163DOIArticle
http://onlinelibrary.wiley.com/doi/10.1002/2017GL075163/abstractPublisherArticle
ORCID:
AuthorORCID
Li, Zefeng0000-0003-4405-8872
Peng, Zhigang0000-0002-0019-9860
Additional Information:© 2017 American Geophysical Union. Received 1 AUG 2017; Accepted 10 SEP 2017; Accepted article online 18 SEP 2017; Published online 5 OCT 2017. This research was supported by the Southern California Earthquake Center (SCEC contribution 7917). SCEC is funded by NSF Cooperative Agreement EAR-1033462 and USGS Cooperative Agreement G12 AC20038. All figures are made with the Generic Mapping Tools by Wessel et al. (2013). We thank Egill Hauksson and Martha Savage for answering various questions regarding the seismic data and the MFAST/TESSA code. The used seismic data are from the Data Center of the Southern California Seismic Network operated by Caltech/USGS.
Group:Seismological Laboratory
Funders:
Funding AgencyGrant Number
Southern California Earthquake Center (SCEC)UNSPECIFIED
NSFEAR-1033462
USGSG12AC20038
Subject Keywords:Seismic anisotropy; Fault zone properties; Seismic waves
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Southern California Earthquake Center7917
Issue or Number:19
Record Number:CaltechAUTHORS:20170918-155840650
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20170918-155840650
Official Citation:Li, Z., & Peng, Z. (2017). Stress- and structure-induced anisotropy in Southern California from two decades of shear wave splitting measurements. Geophysical Research Letters, 44, 9607–9614
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:81548
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:19 Sep 2017 00:21
Last Modified:03 Oct 2019 18:44

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