Synthetic 2D Elastic Full-Waveform Inversion Study of the Ecuadorian Subduction Zone

Date: 4/25/2019

Time: 06:00 PM

Room: Grand Ballroom

Imagiang the subduction zone interface at depth at a kilometer scale is still a huge challenge. Full waveform inversion (FWI) is widely used in the industry for exploration purposes but seismological applications are still rare. We perform synthetic tests to outline the capability of FWI to image structures in the scale of kilometers from earthquake data in a regional subduction zone setting. We utilize a realistic model of the P- and S-wave velocities (Vp and Vs) from the Ecuadorian subduction zone at 0°N and apply 2D-elastic FWI to synthetically modeled waveform data for vertical and horizontal receivers. Perturbations of the original model within the subducted plate with a size of 2 km x 2 km in vS and 4 km x 4 km in vP can be reconstructed in high quality down to approximately 70 km depth. A main frequency of 1 Hz is sufficient to achieve this resolution. In further tests we study the dependency of the results on the location of the sources and the accuracy of the estimated source orientation. The quality of the resulting models does not suffer if the orientation of the sources is not perfectly known but artifacts near the source positions arise. Results where sources are located within the subducted plate are comparable to when the sources are located underneath however the convergence of the inversion is sped up. We find that the inversion of the Vs model prior to the inversion of the Vp model is necessary to guarantee a good reconstruction of both models.

Presenting Author: Andreas Rietbrock

Authors