GLOBAL AND REGIONAL SURFACE-WAVE INVERSIONS - A SPHERICAL-SPLINE PARAMETERIZATION

A surface-wave phase-velocity inversion scheme based upon a compactly supported cubic B-spline basis on a triangular grid of knots with appr oximately equal inter-knot spacing is implemented to perform global, r egional and variable resolution inversions. Numerical results show tha t the inverted phase-velocity maps based upon this method are similar to those obtained using a global spherical-harmonic representation. No nlinear inversions incorporating ray refraction are feasible based upo n the spherical-spline model parameterization and the resulting maps a re only slightly different from those based upon the great-circle appr oximation. A multiresolution analysis is introduced to obtain finer re solution in regions with good ray coverage and lower resolution in reg ions with poor coverage.