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Comparison of earthquake and microtremor ground motions in El Centro, California

Udwadia, F. E. and Trifunac, M. D. (1973) Comparison of earthquake and microtremor ground motions in El Centro, California. Bulletin of the Seismological Society of America, 63 (4). pp. 1227-1253. ISSN 0037-1106.

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Strong earthquake ground shaking has been investigated by the study of 15 events recorded in El Centro, California. The strong-motion records analyzed show that no simple features (e.g., local site conditions) govern the details of local ground shaking. Any effects of local subsoil conditions at this site appear to be overshadowed by the source mechanism and the transmission path, there being no distinctly identifiable site periodicities. Microtremor measurements have been taken in the area surrounding the strong-motion site. The objective was an investigation of possible correlations with strong ground motions and the analysis of site-response characteristics. Basic difficulties in ascertaining local site conditions through such low-amplitude ground motions are illustrated. It has been found that in this area microtremor and earthquake processes are widely different in character, there being little to no correlation between the ground's response to earthquakes and to microtremor excitations. Microtremors have been found to be nonstationary over periods of about a day or so, introducing further uncertainties into inferences from such measurements.

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Additional Information:Copyright © 1973, by the Seismological Society of America. Manuscript received November 6, 1972. We thank Professors D. E. Hudson, G. W. Housner, P. C. Jennings, and Dr. A. G. Brady for many valuable discussions and for critical reading of the manuscript. Mr. Richard Dielman rendered very valuable assistance during the field tests. This research was supported in part by grants from the National Science Foundation.
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Issue or Number:4
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:48925
Deposited By: George Porter
Deposited On:26 Aug 2014 20:35
Last Modified:03 Oct 2019 07:09

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