Geophysics and Tectonics Seminar fall-2021

Subduction initiation is a fundamental component of the plate tectonic cycle and is especially relevant to understanding the changing force balance on plates. The last several years has witnessed a surge of effort aimed at understanding this process. I will address recent observational programs, including two ocean drilling, IODP, expeditions and the South Island Subduction Initiation Experiment, SISIE, in the context of the mechanics of subduction initiation. I will address the major change in plate and plume motion associated with the Pacific Plate at around 50 Ma within the context of a new generation of ultra high-resolution global models of plate tectonics and mantle flow. I will show that the traditional model of subduction initiation in the western Pacific fails to change plate motion fast enough and offer a new reconstruction of the Pacific. The reconstructions, when combined with the dynamic models, can explain the rapid change in Pacific Plate motion.