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A Search for Temporal Variations in Station Terms in Southern California from 1984 to 2002

Lin, Guoqing and Shearer, Peter M. and Hauksson, Egill (2008) A Search for Temporal Variations in Station Terms in Southern California from 1984 to 2002. Bulletin of the Seismological Society of America, 98 (5). pp. 2118-2132. ISSN 0037-1106. doi:10.1785/0120070243.

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We use relative arrival times and locations for similar earthquake pairs that are found using a cross-correlation method to analyze the time dependence of P and S station terms in southern California from 1984 to 2002. We examine 494 similar event clusters recorded by Southern California Seismic Network (SCSN) stations and compute absolute arrival-time variations from the differential arrival-time residuals obtained following event relocation. We compute station terms from the robust means of the absolute arrival-time residuals from all events recorded by each station at 3-month intervals. We observe nine stations with abrupt offsets in timing of 20–70 msec, which are likely caused by equipment changes during our study period. Taking these changes into account could improve the relative location accuracy for some of the event clusters. For other stations, we generally do not see systematic temporal variations greater than about 10 msec. Analysis of residuals along individual ray paths does not reveal any clear localized regions of apparent velocity changes at depth. These results limit large-scale, long-lasting temporal variations in P and S velocities across southern California during this time period to less than about ±0.2%. However, there is an increased fraction of individual travel-time residuals exceeding 20 msec immediately following major earthquakes from source regions near the mainshock rupture.

Item Type:Article
Related URLs:
URLURL TypeDescription
Shearer, Peter M.0000-0002-2992-7630
Hauksson, Egill0000-0002-6834-5051
Additional Information:© 2008 Seismological Society of America. Manuscript received 1 October 2007. We thank Jeanne Hardebeck, David Schaff, and an anonymous reviewer for their detailed and constructive reviews. Funding for this research was provided by the National Earthquake Hazards Reduction Program (NEHRP) and USGS Grant Number 03HQPA0001. This research was also supported by the Southern California Earthquake Center (SCEC), which is funded by National Science Foundation (NSF) Cooperative Agreement Number EAR-0106924 and USGS Cooperative Agreement Number 02HQAG0008. The SCEC contribution number for this article is 1123.
Group:Seismological Laboratory
Funding AgencyGrant Number
National Earthquake Hazards Reduction Program (NEHRP)UNSPECIFIED
Southern California Earthquake Center (SCEC)UNSPECIFIED
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Other Numbering System NameOther Numbering System ID
Southern California Earthquake Center (SCEC)1123
Issue or Number:5
Record Number:CaltechAUTHORS:LINbssa08
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Official Citation:Guoqing Lin, Peter M. Shearer, and Egill Hauksson A Search for Temporal Variations in Station Terms in Southern California from 1984 to 2002 Bulletin of the Seismological Society of America October 2008 98:2118-2132; doi:10.1785/0120070243
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:11920
Deposited By: Archive Administrator
Deposited On:09 Oct 2008 22:52
Last Modified:08 Nov 2021 22:23

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