Focal mechanisms produced by shear faulting in weakly transversely isotropic crustal rocks

Vaclav Vavrycuk


Shear faulting in anisotropic rocks produces non-double couple (non-DC) mechanisms. The non-DC mechanisms can comprise 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 can be expressed advantageously in terms of Thomsen's anisotropy parameters. Shear faulting in crustal rocks with anisotropy strength of 10% can produce an ISO of up to 10% and a CLVD of up to 30%. Such values are significant and detectable in carefully determined focal mechanisms.

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Geophysics, 71 (2006), No.5, D145-D151.
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