CAREER: Modification of a Continent: Seismic Tomography and Imaging of the Northern American Lithosphere

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Changes in the continental lithosphere, the solid outer shell of the Earth, can greatly impact the surface environment of our planet, for example by controlling weather patterns and movement of water. Understanding how changes in the continents depend on processes at depth relies on detailed seismic images of the earth’s interior. With great seismic data coverage, North America is a perfect site for studying continental modification in diverse settings. Although it is one of the most extensively imaged continents, the details of the underlying processes of its evolution are still elusive, largely due to the discrepancies between existing seismic images. The goal of this project is to improve the seismic image resolution of the lithosphere of the North America from the surface to its root. The models will be developed using advanced seismic imaging techniques and complementary seismic data sets that can provide more complete information about the physical properties and features of the continental lithosphere. The results of this project will contribute to the understanding of how the North American continent is built, modified and destroyed. This project will tightly integrate research, education, and public outreach through an intensive “Spartan Shake” summer camp and research-based educational plan for under-represented undergraduate students and high-school science teachers. This project will also enhance the onsite science experience of the participants through analyzing, modeling, and visualizing the environmental seismic data collected by Raspberry Shake 3D seismometers deployed on the Michigan State University campus. This project aims at accurately imaging the lithosphere of North America by mapping 3D variations of both wave speeds and the internal interfaces, including sediment base, Moho, and the lithosphere and asthenosphere boundary. With the more robust seismological constraints of lithospheric structures, the following three key scientific goals can be achieved: (1) understand how the lateral gradients of lithospheric structure control the deformation of the plate margins through thinning, rifting, thickening, and foundering; (2) systematically investigate how asthenosphere interacts with lithosphere across different tectonic environments; (3) investigate the seismic signatures within sedimentary basins and the crust corresponding to underlying lithospheric and asthenospheric processes. Complementary seismic data sets, including ambient-noise-derived Empirical Green’s Functions, and regional and teleseismic data recorded by EarthScope Transportable Array, will be assimilated with different full waveform inversion techniques. This project will provide the first joint inversion of all these data sets under the full waveform inversion framework for more quantitative model comparison, assessment, and interpretation of continental evolution.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.