Russo, R. M., H. Li, B. M. Gomer, A. Montilla, C. R. Bina, and W. P. Richardson, Variability of seismic attenuation in the source region of the July 9, 1997, Cariaco, Venezuela, earthquake, Tectonophysics, submitted, 2000.
Abstract. We measured Q for 733 earthquake-to-station paths in northeastern Venezuela, making use of 181 well-located crustal aftershocks of the July 9, 1997, Cariaco earthquake. Q was determined via the drop in slope with frequency of the log of the spectral ratio of S to P waves from the events. We find that crustal Q in the study region varies significantly as a function both of source-station distance and backazimuth, indicating that Q increases generally with depth in the crust, and that it is a strong function of local and regional geology. We find that Q in the schists of the costal Paria-Trinidad terrane is generally 300-600, Q is 150-250 in deformed strata of the Venezuelan foreland fold and thrust belt, and Q is low, 100-150, in the eastern Gulf of Cariaco and Cariaco Lagoon. Low Q in this small sedimentary basin probably reflects the lack of compaction and induration of these sediments.
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