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Basin Structure Estimation by Waveform Modeling: Forward and Inverse Methods

Ji, Chen and Helmberger, Don V. and Wald, David J. (2000) Basin Structure Estimation by Waveform Modeling: Forward and Inverse Methods. Bulletin of the Seismological Society of America, 90 (4). pp. 964-976. ISSN 0037-1106. doi:10.1785/0119990080.

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We introduce a technique for using broadband seismograms recorded from earthquakes at local and regional distances to refine basin structure. For the region outside the basin, we assume a one-dimensional (1D) crustal model and analytical techniques (GRT) to propagate the energy from sources to the basin edge where the motions are then interfaced with a (2D) finite-difference algorithm (Wen and Helmberger, 1996). We parameterize the basin section by isovelocity layers with linear dipping segments between control points. The control point depths are allowed to vary to improve the modeling of waveform data of stations inside the basin. The comparison between data and synthetics is qualified by a fitness function defined by two factors; the timing shift required for best alignment and the correlation coefficient. The procedure was applied to a strong-motion waveform profile across the extended Los Angeles Basin produced by the 1992 Landers, California earthquake to refine the velocity structure using sensitivity testing and forward modeling. Only the correlation coefficient and amplitude were used because absolute timing was unknown. The procedure was extended to a direct waveform inversion by employing a conjugate gradient approach, which uses numerical derivatives. Numerical tests using the new inversion process with synthetic data demonstrate that it is possible to recover a detailed basin structure, if a sufficient amount of high-quality data exists.

Item Type:Article
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Ji, Chen0000-0002-0350-5704
Additional Information:© 2000 by the Seismological Society of America. Manuscript received 15 June 1999. We thank Lianxing Wen for his help in using the interfacing code. This study was supported by a SCEC contract funded by NSF EAR 8920136 and by the USGS 99HQGR0038. This is Contribution Number 8629 of the Division of Geological and Planetary Sciences, California Institute of Technology.
Funding AgencyGrant Number
Southern California Earthquake Center (SCEC)UNSPECIFIED
NSF Cooperative AgreementEAR 8920136
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Caltech Division of Geological and Planetary Sciences8629
Issue or Number:4
Record Number:CaltechAUTHORS:20121211-135304099
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:35916
Deposited By: Tony Diaz
Deposited On:12 Dec 2012 22:34
Last Modified:09 Nov 2021 23:18

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