Full Waveform Tomography for the upper South Island region, New Zealand

Abstract

In this paper, we apply Full Waveform Tomography (FWT) based on the Adjoint-Wavefield (AW) method to iteratively invert an existing 3-D geophysical velocity model for the upper South Island region, New Zealand. Through the AW method, gradients of model parameters (compressional and shear wave velocities) were computed by implementing the cross-adjoint of forward and backward wave fields. We used L-BFGS/ line search algorithms to obtain a model update. For real data analysis, misfit measurements based on data from broadband stations were utilized. The misfit measure is a frequency-dependent multi-taper travel-time difference at periods from 10 - 40 s. After the iterative inversion, the simulated seismograms computed using our final velocity model shows good agreement to the observed data.