High Resolution Imaging of the Mantle of North America with 3D Wavefield Imaging

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Technical DescriptionThis project will analyze data from the Earthscope Transportable Array (TA) using a novel three-dimensional, seismic wave imaging method called plane wave migration. This method has produced what is arguably the highest resolution image produced from the TA to date. It accomplishes this with a technology derived from the seismic reflection method, which is the primary technology used in oil and gas exploration. The project will use this technology to address three main scientific questions. (1) What is the geometry of the Farallon Plate that North America has been overriding for at least 100 million years? (2) Are dipping interfaces in the upper mantle we have imaged in previous work markers of mantle flow processes? (3) What do these high resolution images tell us about the nature of the region of Earth?s mantle called the transition zone that lies between two global discontinuities at depths of 410 and 660 km? The project will address these questions through four approaches. (1) 3D visualization using tools commonly available for interpretation seismic reflection data in the oil and gas industry. (2) Application of forward modeling methods to appraise the reliability of our imaging results and to test more detailed hypotheses that will arise form approach (1). (3) Comparison of our results with different approaches produced by other scientists. (4) Further technical developments of the imaging technology that will be applied in the project.Broader significance and importanceThe USArray element of Earthscope was built to provide the data to provide a new understanding of the processes that have shaped the North American continent. Seismic imaging technologies were the main approach to addressing this large issue. This project is important for providing the highest resolution images yet obtained with these data and relating them in true geometry to related work by others. This has the potential to dramatically change our perspectives on many elements of North American geology by being able to see what was previously not possible. This has broad impacts for the oil and gas industry as fundamental work that can impact understanding of geologic processes that shape North American geology. We also plan to produce a number of data products that can be used for science education at all levels.