A combination of a lesser degree of anisotropy and a more detailed layer configuration will possibly also yield a satisfactory curve fit. The results for different events agree well, warranting an inversion for a depth-velocity profile of southern California down to a depth of around 250 km. It was not possible to fit the data with a smoothly varying depth-velocity model by inverting for Rayleigh and Love wave phase velocities simultaneously. A combination of a lesser degree of anisotropy and a more detailed layer configuration could possibly also yield a satisfactory fit. Also, further research needs to be done to verify the reliability of the Love wave results.
Subcrustal anisotropy is likely to depend on frozen-in orientation of minerals.
In this case, with SH velocities being faster than SV velocities, this interpretation would point to the past or present existence of horizontal flow in the upper mantle in the southern California area. In conclusion, with the reservations concerning the reliability of the Love wave phase velocity results and the independent isotropic inversion, we find that these results provide some interesting information about the velocity structure of the upper 250 km under southern California. These preliminary results indicate that further research should be done when more data becomes available, and possibly using a more sophisticated inversion procedure. References Brune, J.N. and Dorman, J., 1963. Seismic waves and Earth structure in the Canadian shield.