Subduction zones are among the most important tectonic features on the Earth's surface and represent prime sites for earthquakes, volcanoes, and tsunami hazards. Subduction is also vitally important for understanding the Earth's interior; Earth's long-term evolution is driven by the dynamics of the mantle, and the recycling of oceanic plates back into the mantle through subduction is a major driver for mantle processes. Understanding how slabs sink from the surface to the base of the mantle - and how they interact with the mantle around them - is crucial for understanding the mantle as a dynamic system. The scientific challenge that this CAREER project aims to address is to understand how subducting slabs deform the mantle around them as they descend through the deep mantle using measurements of seismic waves.
Observations and modeling of seismic anisotropy will be used to probe subduction dynamics in three regions: the deep upper mantle, the transition zone, and the lowermost mantle. I will examine the pattern of anisotropy and flow in the deep upper mantle beneath subducting slabs, using detailed shear wave splitting data sets to test hypotheses for controls on sub-slab mantle flow. I will explore how subducting slabs deform the transition zone and uppermost lower mantle and whether the style of deformation is related to the dynamic behavior of "stagnant" vs. "non-stagnant" slabs. Finally, I will interrogate the geometry of anisotropy at the base of the mantle in the D" layer, with the goal of understanding how slab remnants impinging on the core-mantle boundary (CMB) drive flow, and how flow patterns are related to other structures above the CMB such as low shear velocity provinces. The research component of this project will be complemented by an education and outreach effort which will focus on providing high school teachers with research experience on broadband field seismology deployments through a pilot program to be called FEST (Field Experiences for Science Teachers). A prime strategy for translating research into the structure and dynamics of the deep Earth to the general public is to involve teachers in deep Earth research, and field-based projects will offer a highly immersive and meaningful research experience.
