BOOTSTRAPPING SHEAR-WAVE SPLITTING ERRORS

We have developed a bootstrap method to estimate errors associated wit h inverting SKS waveforms for shear-wave splitting parameters. Althoug h presented for shear-wave splitting inversions, this method is suitab le for any waveform inversion procedure. The bootstrap error estimatio n method consists of multiple inversions of simulated data that imitat e the original data with differing noise sequences. The results of the bootstrap inversions are used to directly calculate variances and cov ariances for all model parameters. We employ a bootstrap error estimat ion technique to nonlinear inversion for shear-wave splitting paramete rs. Since seismic data have correlated errors, the bootstrap method wa s modified for stationary bandlimited time series. This modified boots trap method was applied to shear-wave splitting measurements from over 60 pairs of horizontal seismograms. The method is stable under a larg e range of noise conditions. By using this bootstrap method, we can di stinguish among data with no apparent splitting, data with splitting, and noisy data.