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Instrumental intensity distribution for the Hector Mine, California, and the Chi-Chi, Taiwan, earthquakes; comparison of two methods

Vladimir Sokolov and David J. Wald
Instrumental intensity distribution for the Hector Mine, California, and the Chi-Chi, Taiwan, earthquakes; comparison of two methods
Bulletin of the Seismological Society of America (August 2002) 92 (6): 2145-2162

Abstract

We compare two methods of seismic-intensity estimation from groundmotion records for the two recent strong earthquakes: the 1999 (M 7.1) Hector Mine, California, and the 1999 (M 7.6) Chi-Chi, Taiwan. The first technique utilizes the peak ground acceleration (PGA) and velocity (PGV), and it is used for rapid generation of the instrumental intensity map in California. The other method is based on the revised relationships between intensity and Fourier amplitude spectrum (FAS). The results of using the methods are compared with independently observed data and between the estimations from the records. For the case of the Hector Mine earthquake, the calculated intensities in general agree with the observed values. For the case of the Chi-Chi earthquake, the areas of maximum calculated intensity correspond to the areas of the greatest damage and highest number of fatalities. However, the FAS method produces higher-intensity values than those of the peak amplitude method. The specific features of ground-motion excitation during the large, shallow, thrust earthquake may be considered a reason for the discrepancy. The use of PGA and PGV is simple; however, the use of FAS provides a natural consideration of site amplification by means of generalized or site-specific spectral ratios. Because the calculation of seismic-intensity maps requires rapid processing of data from a large network, it is very practical to generate a "first-order" map from the recorded peak motions. Then, a "second-order" map may be compiled using an amplitude-spectra method on the basis of available records and numerical modeling of the site-dependent spectra for the regions of sparse station spacing.


ISSN: 0037-1106
EISSN: 1943-3573
Coden: BSSAAP
Serial Title: Bulletin of the Seismological Society of America
Serial Volume: 92
Serial Issue: 6
Title: Instrumental intensity distribution for the Hector Mine, California, and the Chi-Chi, Taiwan, earthquakes; comparison of two methods
Affiliation: Karlsruhe University, Geophysical Institute, Karlsruhe, Federal Republic of Germany
Pages: 2145-2162
Published: 200208
Text Language: English
Publisher: Seismological Society of America, Berkeley, CA, United States
References: 59
Accession Number: 2003-010743
Categories: Seismology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 3 tables, geol. sketch maps
N33°00'00" - N35°00'00", W118°00'00" - W115°00'00"
N23°00'00" - N25°00'00", E120°00'00" - E121°30'00"
Secondary Affiliation: U. S. Geological Survey, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute.
Update Code: 200304
Program Name: USGSOPNon-USGS publications with USGS authors
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