Constant and Frequency-dependent Attenuation from Vertical Seismic Profiles in Fractured Granite and Thinly Layered Sediment

Author(s):  
C.D. Cantú Bendeck ◽  
R.A. Clark ◽  
A.D. Booth ◽  
W. Wills
Geophysics ◽  
1997 ◽  
Vol 62 (5) ◽  
pp. 1456-1464 ◽  
Author(s):  
M. S. Sams ◽  
J. P. Neep ◽  
M. H. Worthington ◽  
M. S. King

A series of experiments to determine the elastic properties of a sequence of saturated sedimentary rocks over as wide a frequency range as possible was carried out at the Imperial College borehole test site. These experiments fall into four categories: vertical seismic profiles (VSPs) within the frequency range 30–280 Hz, crosshole surveys (0.2–2.3 kHz), sonic logging (8–24 kHz), and laboratory measurements (300–900 kHz). The intrinsic attenuation and velocity of compressional and shear waves were measured whenever possible. Velocity dispersion is observed for both compressional and shear waves. The intrinsic attenuation of compressional waves is frequency dependent with a peak in the attenuation in the sonic frequency band. The data were modeled assuming the attenuation is caused by local fluid flow in pores of small aspect ratio. The modeling indicates that the intrinsic attenuation may be dominated by cracks with aspect ratios of around [Formula: see text] to [Formula: see text].


1996 ◽  
Vol 86 (2) ◽  
pp. 524-529
Author(s):  
Hayrullah Karabulut ◽  
John F. Ferguson

Abstract An extension of the boundary integral method for SH waves is given for transversely isotropic media. The accuracy of the method is demonstrated for a simple flat interface problem by comparison to the Cagniard-de Hoop solution. The method is further demonstrated for a case with interface topography for both surface and vertical seismic profiles. The new method is found to be both accurate and effective.


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