Research focuses on global, numerical convection models with realistic plate boundaries, rheological and thermo-chemical contrasts, and improved constraints from seismology. The force partitioning in the mantle affects intraplate and plate boundary seismo-tectonics, and studying the mantle system by mechanical modeling holds the key to understanding plate motions and geologically recorded tectonic events. Efforts are divided into two research projects which are interrelated and have strong educational components. Project one uses circulation computations for an inversion of seismology data to evaluate the range of viscosity variations that are required by observables and laboratory results on the creep behavior of rocks (viscous tomography). Project two incorporates faulted margins into a global model (slabs, keels, and plates). Slabs drive and control the speed of the plates, and a more realistic inclusion of plate boundaries into global models is needed. It is evaluated to what degree slabs and trench motions vs. the tectosphere: asthenosphere contrast control global dynamics such as geopotential fields and seismic coupling. The unifying theme of research and educational efforts is the use of global flow models and structure derived from seismology and mineral physics. The goal is to arrive at a new kind of mantle circulation model that elucidates the roles of the asthenosphere in shaping plate tectonics and organizing deep Earth structure. The educational efforts in this project focus on course material for a new numerical methods class and two solid earth software modules for exploring mantle flow and tomography, both openly developed and freely shared. The goal is to allow learning through experimentation with modified research tools. Those tools are customizable so that they are useful for both general undergrad and graduate classes. Efforts strengthen the quantitative skills of students needed to tackle interconnected problems; useful for grad students to solve outstanding questions in mantle dynamics, and for non-specialists who need to make informed choices during planetary environmental challenges. Work contributes to a more transparent representation of disciplinary research results where traditional means of scientific communication are becoming unduly limiting. By providing both fundamental training in quantitative analysis and examples for novel seismological and geodynamical model sharing, the robustness of extra-disciplinary constraints are easier to evaluate. This is crucial if we are to accelerate progress on complex problems in plate tectonics and earth science in general.
This project supported research on the dynamics of plate tectonics. In particular, we explored how subducting slabs drive and deform lithospheric plates, and how this oceanic plate system interacts with the strong interiors of the continents which are thought to beunderlain by deep keels. Studying such processes provides clues on how continuously recycled oceanic plates interact and shape the more persistent continental ones. We were able to document the relative strength of the slab and keel components of mantle convection that are stirring the mantle, and what this implies for the long-term thermal evolution of Earth. The six year project partially supported 30 peer-reviewed publications. Moreover, three PhD students (one still in our program), one MSc student, and a post-doc were trained thanks to grant support. Out of those six junior scientists, three are female, and two have already gone on to professorships or academic post-doctoral appointments. On the educational side, the project also supported the development of a new type of Earth systems modeling graduate class with extensive lecture notes and accompanying computer exercises. Those are openly shared online as a textbook style resource. Moreover, the grant funded the establishment of a comprehensive software research and teaching framework that serves to make research tools more readily available to practitioners outside the discipline, and for undergraduate and graduate teaching. Results from these efforts have served to further disseminate research tools and results to the wider community, and several external groups have adopted our software for their research. as documented by a number of independent publications. Throughout our work, we have created numerous visualizations and other material which are shared openly online and were featured in a number of venues, including Discover Magazine online. These virtual resources complement our personal outreach efforts, such as a guided tour at the Los Angeles County Museum of Art.
