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Shear wave structure of a transect of the Los Angeles basin from multimode surface waves and H/V spectral ratio analysis

Perton, Mathieu and Spica, Zack J. and Clayton, Robert W. and Beroza, Gregory C. (2020) Shear wave structure of a transect of the Los Angeles basin from multimode surface waves and H/V spectral ratio analysis. Geophysical Journal International, 220 (1). pp. 415-427. ISSN 0956-540X. https://resolver.caltech.edu/CaltechAUTHORS:20200130-154313815

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Abstract

We use broad-band stations of the ‘Los Angeles Syncline Seismic Interferometry Experiment’ (LASSIE) to perform a joint inversion of the Horizontal to Vertical spectral ratios (H/V) and multimode dispersion curves (phase and group velocity) for both Rayleigh and Love waves at each station of a dense line of sensors. The H/V of the autocorrelated signal at a seismic station is proportional to the ratio of the imaginary parts of the Green’s function. The presence of low-frequency peaks (∼0.2 Hz) in H/V allows us to constrain the structure of the basin with high confidence to a depth of 6 km. The velocity models we obtain are broadly consistent with the SCEC CVM-H community model and agree well with known geological features. Because our approach differs substantially from previous modelling of crustal velocities in southern California, this research validates both the utility of the diffuse field H/V measurements for deep structural characterization and the predictive value of the CVM-H community velocity model in the Los Angeles region. We also analyse a lower frequency peak (∼0.03 Hz) in H/V and suggest it could be the signature of the Moho. Finally, we show that the independent comparison of the H and V components with their corresponding theoretical counterparts gives information about the degree of diffusivity of the ambient seismic field.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1093/gji/ggz458DOIArticle
ORCID:
AuthorORCID
Perton, Mathieu0000-0001-5141-5255
Spica, Zack J.0000-0002-9259-1973
Clayton, Robert W.0000-0003-3323-3508
Beroza, Gregory C.0000-0002-8667-1838
Additional Information:© 2019 The Author(s). Published by Oxford University Press on behalf of The Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model). Accepted 2019 October 8. Received 2019 September 23; in original form 2019 May 16. Published: 10 October 2019. We thank Jorjón Castillo Castellanos for providing us the Green’s functions computed by Yiran Ma. This research was supported by the Southern California Earthquake Center (Contribution No. 9096). SCEC is funded by NSF Cooperative Agreement EAR-1600087 & USGS Cooperative Agreement G17AC00047. Zack Spica thanks the long-term visiting program of the Earthquake Research Institute. We thank the partners of the LASSIE survey: Nodalseismic (Dan Hollis and Mitchell Barklage), USGS (Elizabeth Cochran), UCLA (Paul Davis) and CalPoly Pomona (J. Polet). The authors are grateful for the editorial work of Andrea Morelli and thorough reviews from Michael Asten and another anonymous referee.
Group:Seismological Laboratory
Funders:
Funding AgencyGrant Number
Southern California Earthquake Center (SCEC)UNSPECIFIED
NSFEAR-1600087
USGSG17AC00047
Subject Keywords:Tomography; Seismic noise; Site effect; Surface waves and free oscillations
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Southern California Earthquake Center9096
Issue or Number:1
Record Number:CaltechAUTHORS:20200130-154313815
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20200130-154313815
Official Citation:Mathieu Perton, Zack J Spica, Robert W Clayton, Gregory C Beroza, Shear wave structure of a transect of the Los Angeles basin from multimode surface waves and H/V spectral ratio analysis, Geophysical Journal International, Volume 220, Issue 1, January 2020, Pages 415–427, https://doi.org/10.1093/gji/ggz458
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:101016
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:30 Jan 2020 23:50
Last Modified:30 Jan 2020 23:50

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