SPS Award for Outstanding Undergraduate Research
On the Relative Significance of Lithospheric Weakening Mechanisms for Sustained Plate Tectonics
Sophia Sánchez-Maes's world line originates in the New Mexico borderlands. A scientific realist working in mathematical relativity, her current theoretical research probes whether spacetime might have an exotic topology. She is employed by NASA's Jet Propulsion Laboratory, where she works to find and characterize worlds beyond our solar system. In her continuing geological work in conjunction with mentor Jun Korenaga, she showed that water is a necessary but insufficient condition for plate tectonics; making surface oceans a potential geologic observable for exo-earths. She has also served as principal investigator on a NASA Space grant investigating stellar activity, and written code for the Mars Rover. For her work, she has been designated an NSF Young Scholar, received the international Guiseppe Sciacca early-career prize for research, presented her findings to President Barack Obama, and was awarded the National Jefferson Award for greatest public service by an individual 25 or under. A member of Timothy Dwight college at Yale University, she is candidate for double major in physics (int.) and astrophysics. She will pursue a Ph.D. and continue into a career in physics as a researcher. She writes for the scientific magazine and is president of the Yale Society of Physics Students. She makes habit of reading short stories, writing science fiction, and keeping written correspondence.
Plate tectonics requires the bending of strong plates at subduction zones, which is difficult to achieve without a secondary weakening mechanism. Two classes of weakening mechanisms have been proposed for the generation of ongoing plate tectonics, distinguished by whether or not they require water. Here we show that the energy budget of global subduction zones offers a simple yet decisive test on their relative significance. Theoretical studies of mantle convection suggest bending dissipation to occupy only 10-20 % of total dissipation in the mantle, and our results indicate that the hydrous mechanism in the shallow part of plates is essential to satisfy the requirement. Thus, surface oceans are required for the long-term operation of plate tectonics on terrestrial worlds. Establishing this necessary and observable condition for sustained plate tectonics carries important implications for planetary habitability at large.