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Seismic Imaging of the Eastern Alaska Range Crustal Structure

Description: 

The Denali fault is an active right-lateral continental strike-slip fault that transects the North American Cordillera from northern British Columbia to the Bering Sea shelf. The structural evolution of the Denali fault as a major continental fault system that has accommodated hundreds of kilometers of displacement implies that the fault is a significant geophysical feature. However, the complex and diverse geology surrounding the fault, and variability in geologic and geophysical data resolution, cause the perceived geophysical signature of the fault to be spatially variable. Here, we explore the geologic evolution of the eastern Alaska Range and the central portion of the Denali fault by integrating new understanding of the geologic framework with new seismic images of the crustal structure. Our new seismic images utilize all available data (1999-2022) from both temporary and permanent broadband seismometers available from the IRIS DMC. These data include the recently deployed ICED array (Z5 network) that targeted the eastern Alaska Range and adjacent section of the Denali Fault that had previously been under-resolved by the TA and other temporary deployments. We combine new ambient noise based tomography inferring the shear wave velocities, P receiver functions to define the Moho topography, and a new machine learning based catalog of seismicity together to infer the structural heterogeneity of the crust around the Denali fault. Complimentary geophysical information from this section of the fault corroborates geologic observations indicating that the Denali fault is a primary lithospheric-scale boundary, with some sections that clearly indicate a step across the Moho.

Session: Cordilleran Strike-Slip Faults as Seismogenic and Seismological Features - I

Type: Oral

Date: 5/2/2024

Presentation Time: 05:15 PM (local time)

Presenting Author: Meghan

Student Presenter: No

Invited Presentation: 

Authors