A High-Resolution 3D Vs Model of Alaska Revealed by Surface Waves

Date: 4/26/2019

Time: 06:00 PM

Room: Grand Ballroom

Alaska is tectonically complex, including subduction zones, the highest mountains in North America, and the cordilleran-cratonic boundary. Although the expression of these geological structures in the deeper crust and upper mantle remains relatively unclear, the deployment of the EarthScope Transportable Array (TA) provides a new data of exceptional quality that can be exploited to improve knowledge of earth structure beneath Alaska. Based on the seismic data collected by the TA and several other local and regional networks, we present a 3D Vs model of the crust and upper mantle using surface wave datasets constructed by joint inversion of Rayleigh wave phase and group dispersion measurements extracted from both ambient seismic noise and earthquake records. We apply a Bayesian Monte Carlo approach in the inversion procedure to these data to constrain the isotropic Vs structure of the crust and uppermost mantle. The posterior distribution that results yields probabilistic information about Vs structure, including the mean model and model uncertainty. The 3D model captures many structural features, including the major sedimentary basins, the subducting Pacific plate to a depth of about 150 km, the craton underlying the North Slope, and a large region of deformation surrounding the Alaska range in central Alaska. We test the model using receiver functions, which are highly complicated across much of Alaska, in order to provide insight into future model improvements in the near future.

Presenting Author: Lili Feng

Authors