Velocity and attenuation inversion in downhole arrays via a hybrid optimization algorithm

Domniki Asimaki, & Jamison H. Steidl

Published 2005, SCEC Contribution #877

A seismic waveform inversion algorithm is proposed for the estimation of elastic soil properties using low amplitude, downhole array recordings. Based on a global optimization scheme in the wavelet domain, complemented by a local least-square fit operator in the frequency domain, the hybrid scheme can efficiently identify the optimal solution vicinity in the stochastic search space, whereas the best fit model detection is substantially accelerated through the local deterministic inversion. Results are presented for selected aftershocks of the Mw 7.0 Sanriku-Minami earthquake in Japan, recorded by the Kik-Net Strong Motion Network, and show that while the algorithm provides robust estimates of the impedance structure, the near surficial attenuation is overestimated due to scattering effects. Using the inverted profiles, the nonlinear site response is estimated and compared with the recorded time-histories of the mainshock.

Citation
Asimaki, D., & Steidl, J. H. (2005). Velocity and attenuation inversion in downhole arrays via a hybrid optimization algorithm. Poster Presentation at 11th International Association for Computer Methods and Advances in Geomechanics Conference.