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Stress Orientations Obtained from Earthquake Focal Mechanisms: What Are Appropriate Uncertainty Estimates?

Hardebeck, Jeanne L. and Hauksson, Egill (2001) Stress Orientations Obtained from Earthquake Focal Mechanisms: What Are Appropriate Uncertainty Estimates? Bulletin of the Seismological Society of America, 91 (2). pp. 250-262. ISSN 0037-1106. https://resolver.caltech.edu/CaltechAUTHORS:20130220-112736703

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Abstract

Crustal stress orientations provide important information about the mechanics of regional deformation. Numerous methods exist for inverting earthquake focal mechanisms for stress orientation, and the more widely used methods usually obtain similar results for similar data sets. However, error estimates are highly variable, complicating the interpretation of results. The southern California stress field, for example, contains much statistically significant spatial and temporal variability according to the error estimates of one method (Michael, 1984, 1987b), but very little according to those of another (Gephart and Forsyth, 1984). To resolve whether the southern California stress field is generally homogeneous or heterogeneous, we must determine which of the error estimates best reflects the true inversion uncertainty. To do this, we tested both methods on a suite of synthetic focal mechanism data sets containing random errors. The method of Gephart and Forsyth (1984) usually provides more accurate estimates of stress orientation, especially for high-quality data sets, but its confidence regions are in most cases too large. The method of Michael (1984, 1987b) is more accurate for very noisy data sets and provides a more appropriate estimate of uncertainty, implying that the stress field in southern California is probably heterogeneous.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1785/0120000032DOIArticle
http://bssa.geoscienceworld.org/content/91/2/250PublisherArticle
ORCID:
AuthorORCID
Hauksson, Egill0000-0002-6834-5051
Additional Information:© 2001 Seismological Society of America. Manuscript received 9 March 2000. We thank Andrew Michael and John Gephart for valuable discussions and for providing their inversion codes, and Max Wyss and an anonymous reviewer for their helpful comments on the manuscript. This research was supported by the Southern California Earthquake Center (SCEC). SCEC is funded by NSF Cooperative Agreement EAR-8920136 and USGS Cooperative Agreements 14-08-0001-A0899 and 1434-HQ-97AG01718. The SCEC Contribution Number for this paper is 504. Contribution Number 8706, Caltech Division of Geological and Planetary Sciences.
Group:Seismological Laboratory
Funders:
Funding AgencyGrant Number
Southern California Earthquake Center (SCEC)UNSPECIFIED
NSFEAR-8920136
USGS14-08-0001-A0899
USGS1434-HQ-97AG01718
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Southern California Earthquake Center (SCEC)504
Caltech Division of Geological and Planetary Sciences8706
Issue or Number:2
Record Number:CaltechAUTHORS:20130220-112736703
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20130220-112736703
Official Citation:Jeanne L. Hardebeck and Egill Hauksson Stress Orientations Obtained from Earthquake Focal Mechanisms: What Are Appropriate Uncertainty Estimates? Bulletin of the Seismological Society of America, April 2001, v. 91, p. 250-262, doi:10.1785/0120000032
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:37017
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:20 Feb 2013 21:11
Last Modified:03 Oct 2019 04:43

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