CAREER: Developing a Multi-Parameter Seismic Model of North America

Jointly constraining and interpreting multiple seismic parameters enables geophysicists to better investigate physical properties of Earth materials. Such studies may allow scientists to infer distributions of temperature, water content, and deformation. This project aims to develop a multi-parameter seismic model for North America by using state-of-the-art full waveform inversion technology and high-quality waveform records collected by the USArray over the past decade.

This community-shared, multi-parameter seismic model will include 3-D variations in velocities, anisotropy, shear attenuation and the associated uncertainties. Jointly interpreting these parameters will enable the investigators to address important scientific problems related to depth-dependent anisotropy and water distribution within the mantle transition zone.

Solving these issues is important for our understanding of the physical characteristics of the lithosphere, asthenosphere and mantle transition zone. Furthermore, this CAREER project will support an early career PI and several Ph.D. graduate and undergraduate students. The PI will promote high-performance computation in Geophysics education, engage undergraduate students in research and participate in UTD STEM summer camps for high school students.

The Dallas area has large African, Hispanic and Asian American communities, the PI will attract high school students from these communities to participate this summer camp program. The developed multi-parameter seismic model will be shared online for public and research usages. Results from this project will be disseminated via peer-reviewed publications and presentations at national/international meetings.

This project will combine full waveform inversion and high-quality USArray records to construct a comprehensive seismic model for North America, which will enable the team to tackle the following scientific problems. (1) The 3-D azimuthal anisotropy structure in the developed comprehensive model will enable us to distinguish “frozen-in” lithospheric deformation and present-day asthenospheric flows. In addition, jointly interpreting radial and azimuthal anisotropy enables them to test the anisotropy cause hypothesis for the mid-lithosphere discontinuity; (2) Considering the high water solubilities of wadsleyite and ringwoodite, the mantle transition zone might act as a huge water reservoir inside the Earth.

Seismic attenuation has been considered as an important proxy for delineating the distribution of water. By jointly interpreting velocity and attenuation results taken from the developed comprehensive model, this project aims to answer the question: “Is the mantle transition zone underneath North America highly hydrated?” (3) Quantifying uncertainty and resolution is still challenging in full waveform inversion applications.

This project will develop algorithms to efficiently evaluate the posterior covariance and resolution matrix, which will be applied to quantify uncertainty of the developed, multi-parameter seismic model of North America. The PI will also promote interactions between students and experts from the energy industry through workshops and summer internships.

This project will enable the PI to train graduate and undergraduate students for seismology related research.

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.