Title of the talk: Cross-scale models of subduction and megathrust dynamics.
Within the thermo-chemically convecting mantle system, subducting slabs represent the major plate driving force, and with that control much of tectonic deformation. I review some of the community and our own team's efforts to analyze and constrain subduction zone dynamics, from a global to regional long-term, to a local, short-term term perspective. While lithospheric rheology is crucial for understanding the bending of the slab at the trench, a range of evidence points toward only moderate stiff slabs. This implies a potentially important role of the megathrust interface and accretionary wedge structure for plate dynamics. Sediments can play both a lubricating and a breaking role in this context, as can be explored using a range of regional geodynamic models. On shorter time scales, the disastrous 2011 M9 Tohoki-oki earthquake in Japan has served to illuminate a range of complex behavior throughout the seismic cycle. I highlight time-evolving signals in both geodetic and crustal stress indicators, before and after the earthquake. Those constraints point toward a future, integrative model of subduction zone mechanics which we are currently exploring with both forward and inverse approaches. Using the same computational framework for both, we are able to better model co-seismic deformation from the M9, for example, and show that on land GNSS data contains sufficient information to not just solve for fault slip, but also lateral variations in shear modulus. Such novel imaging approaches point toward new ways of understanding the dynamics of subduction, and with it, the controls on megathrust state over time.
Short bio: Thorsten Becker holds the Shell Foundation Distinguished Chair in Geophysics at the Jackson School of Geosciences and is a faculty associate of the Oden Institute for Computational Engineering & Sciences at UT Austin. His main research interests are in geodynamics and seismology, focusing on how planets' interior and surface systems have co-evolved. He has worked on more than 150 publications, is a Fellow of the American Geophysical Union, and a recipient of IUGG LIP's Evgueni Burov and EGU's Augustus Love Medals.
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