Searching for the Difference in Attenuation between the Fast and Slow Shear Waves
Measurements of shear-wave splitting parameters (fast polarization direction PHI and splitting time DT) have become a powerful and routine technique to study the deformation field of the earth's interior. While it is evident that velocity anisotropy can lead to significant arrival-time difference between the fast and slow shear waves, the question of whether the two waves have observable difference in attenuation has rarely been addressed. In principle, such a difference in attenuation is likely to be observed, especially from local shear-waves recorded in areas with fluid-filled cracks; relative to the fast wave, the slow wave may experience higher attenuation. Successful detection and characterization of the difference in attenuation may provide additional constraints on the properties of the anisotropic media. We have developed and tested a grid-searching procedure to search for the optimal PHI, DT, and the relative attenuation factor (as quantified by t* which is travel-time over Q) between the fast and slow shear waves that give rise to the maximum cross correlation coefficient between the corrected fast and slow waves. The procedure can be used for both SKS/SKKS phases and shear-waves originated from local earthquakes. Details about the procedure and its applications on seismic data recorded at a number of locations will be presented.
S. S. Gao et al., "Searching for the Difference in Attenuation between the Fast and Slow Shear Waves,", vol. 85, no. 47 American Geophysical Union (AGU), Dec 2004.
AGU Fall Meeting (2004: Dec. 13-17, San Francisco, CA)
Geosciences and Geological and Petroleum Engineering
Keywords and Phrases
Seismology; Body Waves; Lithosphere
Article - Conference proceedings
© 2004 American Geophysical Union (AGU), All rights reserved.