Robert Porritt has been granted an NSF Earth Sciences postdoctoral fellowship to carry out a research and education plan at the University of Southern California. He will study the internal structure of the North American Craton through seismic imaging methods. The project aims to delineate sub-horizontal layering in the continental lithosphere, which would indicate formation of the craton by successively stacking oceanic lithosphere. To accomplish this, receiver function, surface wave, and body wave imaging techniques will be brought together in a consistent joint inversion framework. The three methods have complementary sensitivities such that where one method is ambiguous; the other two provide unique constraints. Together, the joint inversion will constrain velocity structure and highlight internal layers. The project will start by imaging the Hudson's Bay region at the heart of the craton and then will expand to include the contiguous United States by utilizing the USArray of EarthScope.
The mechanism of creating long standing continental crust is an outstanding fundamental question in earth science. Seismic wavespeed models provide physical constraints necessary for placing geochemical observations, initiating geodynamic models, and can be compared with other geophysical observations. To facilitate this cross-disciplinary work, the models generated through this work will be readily available to the public and other researchers. The education arm of the fellowship contains elements at both the graduate and undergraduate level. Competitive proposals for interns will be submitted to the IRIS Internship and SCEC Internship programs to pair enthusiastic undergraduates with the project. Additional undergraduate outreach will include interaction with a USC field course in Morocco. The graduate level component is through the USArray short course, which brings together graduate students from across the globe to spread ideas and best practices for seismic data processing with the insurmountable dataset being generated by EarthScope and its USArray component.
