Collaborative Research: Heterogeneities of the Alaska Megathrust: From the Overriding Plate to the Subducting Slab

Subduction, where one tectonic plate moves beneath another, can lead to large magnitude earthquakes. The Alaska Peninsula has a history of such events, making it an ideal location to explore the relationship between different geological features and these earthquakes. This project will use high-quality data from community seismic experiments to better understand the structure of the Earth's plates in this region. This will in turn allow testing hypotheses related to how structures in the overriding plate may influence earthquake processes. This research not only benefits Alaska but contributes to a global understanding of earthquake processes, ultimately helping to better prepare for and mitigate earthquake hazards at subduction zones. The broader impacts include training opportunities for graduate and undergraduate students at minority-serving institutions and support for a postdoctoral scholar. The proposed project focuses on seismic imaging of the Alaska-Aleutian subduction zone, specifically the Alaska Peninsula, to investigate the relationships between the structure of the subduction zone and megathrust earthquake properties. The study aims to enhance the understanding of factors influencing megathrust earthquakes. Utilizing data from the Alaska Amphibious Community Seismic Experiment, EarthScope Transportable Array, and USGS Alaska Earthquake Center, the research will jointly employ scattered wave and body wave tomography to obtain high-resolution constraints on the structure of the plate interface, overriding and subducting plates. The overarching goal is to test hypotheses regarding the roles of pre-existing structures in the overriding crust in megathrust earthquake processes. The canonical view of the seismogenic megathrust as a planar fault with variably locked asperities remains a useful framework, but questions persist about the specific roles of these features in seismogenesis. The research will address these uncertainties by analyzing the depth and seismic structure of the plate interface, as well as variations along dip and strike directions. Additionally, the seismic structures of the overriding and subducting plates will be examined to determine their roles in slip behaviors. By integrating scattered waves and body-wave tomography, the project aims to identify correlations between different structural features and interseismic/coseismic slips. The ultimate goal is to enhance the fundamental understanding of how geological structures influence seismic behavior, not only in Alaska but also in subduction zones worldwide, aligning with community initiatives such as Subduction Zones in 4-Dimensions (SZ4D). This project is jointly funded by the Marine Geology and Geophysics program in the Division of Ocean Sciences, the Established Program to Stimulate Competitive Research (EPSCoR), and the Geophysics program in the Division of Earth Sciences. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.