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Seismic Response of Nenana Basin, Central Alaska, From 3D Seismic Wavefield Simulations of Local and Regional Earthquakes

The geometry and low wavespeeds of sedimentary basins trap seismic waves, leading to amplification and long-duration shaking. This seismic response of a sedimentary basin can be relevant both for understanding active tectonics and for assessing seismic hazards relevant to society. Using 3D seismic wavefield simulations, we can explore complex seismic wavefield propagation in the basins, wiggle by wiggle and frame by frame. Nenana basin in central Alaska is a promising region for studying basin wave propagation because its basement surface has been estimated from detailed active-source imaging and because there are about 15 broadband seismic stations in the region, enabling comparisons between simulations results (synthetics) and observations (data). We have created three Nenana basin region models in different mesh sizes: 1) the Berg et al. (2020) 3D tomographic model, 2) the Berg model with an embedded basin model, 3) a simplified model of an elliptical basin embedded in a background layered (1D) model. By comparing and analyzing the seismic simulation results in both time and frequency domain from these models, together with the real data collected in this region, we can investigate the detailed mechanism of basin amplification for a variety of different incoming waves and frequencies. We have also compared the basin seismic response from realistic models with recordings from seismic stations in the region, and, using these differences, we have generated sensitivity kernels that could potentially be used for a future tomographic inversion that accounts for regional and basin structures.

Session: Numerical Modeling in Seismology: Developments and Applications

Type: Oral

Room: 209C

Date: 4/20/2023

Presentation Time: 04:45 PM (local time)

Presenting Author: Yuan Tian

Student Presenter: No

Additional Authors