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An experiment in the retrieval of depth and source mechanism of large earthquakes using very long-period Rayleigh wave data

Barbara Romanowicz and Philippe Guillemant
An experiment in the retrieval of depth and source mechanism of large earthquakes using very long-period Rayleigh wave data
Bulletin of the Seismological Society of America (April 1984) 74 (2): 417-437

Abstract

Moment tensor formalism. After illustrating the sensitivity to depth of the eigenfunctions in the period range of 160 to 350 sec, we give several examples of application of the two-step inversion procedure proposed earlier for shorter period Rayleigh wave data (Romanowicz, 1982). We find that for earthquakes below a depth of about 50 km, we are able to resolve depth even when a spherically symmetric average Earth model is used for propagation corrections. This is particularly interesting in the case of large subduction zone earthquakes for which an estimate of the vertical extent of faulting can thus be obtained, independently of aftershock studies, in a very fast and simple manner which does not involve any synthetic seismogram calculations or lateral heterogeneity modeling. For shallower earthquakes, especially those with one steeply dipping nodal plane, the resolution of depth is less precise. Taking lateral heterogeneity into account by using available regionalized phase velocities improves the results marginally. We anticipate that accounting more accurately for the low-order harmonics in the worldwide phase velocity distribution should prove most helpful, since these interfere the most with the theoretical radiation patterns of earthquakes. The determination of depth depends more critically on the source process time, which has to be accounted for especially for horizontally propagating faults.


ISSN: 0037-1106
EISSN: 1943-3573
Coden: BSSAAP
Serial Title: Bulletin of the Seismological Society of America
Serial Volume: 74
Serial Issue: 2
Title: An experiment in the retrieval of depth and source mechanism of large earthquakes using very long-period Rayleigh wave data
Affiliation: Inst. phys. globe, lab. d'etud. geophys. struct. profondes, Paris, France
Pages: 417-437
Published: 198404
Text Language: English
Publisher: Seismological Society of America, Berkeley, CA, United States
References: 34
Accession Number: 1984-049069
Categories: Seismology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: Inst. Phys. Globe; Contrib. No. 717
Illustration Description: illus. incl. 8 tables
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 1984
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