A new fifth parameter for transverse isotropy II: partial derivatives

Abstract

Kawakatsu etal. and Kawakatsu introduced a new fifth parameter, η κ , to describe transverse isotropy (TI). Considering that η κ characterizes the incidence angle dependence of body wave phase velocities for TI models, its relevance for body wave seismology is obvious. Here, we derive expressions for partial derivatives (sensitivity kernels) of surface wave phase velocity and normal mode eigenfrequency for the new set of five parameters. The partial derivative for η κ is about twice as large as that for the conventional η, indicating that η κ should be more readily resolved. While partial derivatives for S velocities are not so changed, those for P velocities are significantly modified; the sensitivity for anisotropic P velocities is greatly reduced. In contrary to the suggestion by Dziewonski & Anderson and Anderson & Dziewonski, there is not much control on the anisotropic P velocities. On the other hand, the significance of η κ for long-period seismology has become clear.