Non-double-couple mechanisms in weak transverse isotropy

Vaclav Vavrycuk

Summary

Shear faulting in anisotropic rocks produces non-double-couple (non-DC) mechanisms. The non-DC components can combine the isotropic (ISO) and compensated linear vector dipole (CLVD) components. The formulas for percentages of the ISO and CLVD are simplified under the assumption of weak transverse isotropy and they can be advantageously expressed in terms of the Thomsen’s weak anisotropy parameters. Shear faulting in crustal rocks with anisotropy strength of 10% can produce the ISO up to 10% and the CLVD up to 30%. Such values are significant and detectable in carefully determined focal mechanisms.

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In: Seismic Waves in Complex 3-D Structures, Report 16, pp. 225-246, Dep. Geophys., Charles Univ., Prague, 2006.
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