Seismic attenuation in Faroe Islands basalts

Shaw, F. and Worthington, M. H. and White, R. S. and Andersen, M. S. and Petersen, U. K. and Group, Seifaba (2008) Seismic attenuation in Faroe Islands basalts. Geophysical Prospecting, 56 (1). pp. 5-20. DOI 2478.2007.00665.x


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We analysed vertical seismic profiling (VSP) data from two boreholes at Glyvursnes and Vestmanna on the island of Streymoy, Faroe Islands, to determine the magnitude and causes of seismic attenuation in sequences of basalt flows. The work is part of SeiFaBa, a major project integrating data from vertical and offset VSP, surface seismic surveys, core samples and wireline log data from the two boreholes. Values of effective seismic quality factor (Q) obtained at Glyvursnes and Vestmanna are sufficiently low to significantly degrade the quality of a surface reflection seismic image. This observation is consistent with results from other VSP experiments in the North Atlantic region. We demonstrate that the most likely cause of the low values of effective Q at Glyvursnes and Vestmanna is a combination of 1D scattering and intrinsic attenuation due to seismic wave-induced fluid flow within pores and microcracks. Tests involving 3D elastic wave numerical modelling with a hypothetical basalt model based on field observations, indicate that little scattering attenuation is caused by lateral variations in basalt structure.

Item Type: Article
Uncontrolled Keywords: 2007 AREP IA55 2008 P
Subjects: 02 - Geodynamics, Geophysics and Tectonics
Divisions: 02 - Geodynamics, Geophysics and Tectonics
Journal or Publication Title: Geophysical Prospecting
Volume: 56
Page Range: pp. 5-20
Identification Number: 2478.2007.00665.x
Depositing User: Sarah Humbert
Date Deposited: 16 Feb 2009 13:03
Last Modified: 23 Jul 2013 10:08

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