Abstract

I’ll be presenting work my students and I have been doing to better understand the mechanical behavior of subduction interface shear zones over both the short timescales of seismic behavior and the long timescales of geodynamic plate motions. I will use observations from both the field and lab to demonstrate that interface rheology is highly sensitive to the ratio of sediment to mafic rocks that are subducted to depth. In considering short timescales, I’ll show how mixed sediment-mafic rock interfaces generate heterogeneous shear zones that may produce seismic behaviors that resemble episodic tremor and slow slip. In considering longer timescales, I’ll demonstrate how the viscosity contrast between sediment and mafic rocks affects subduction plate speeds and sets up potential connections between Earth’s interior dynamics and surface processes that influence sediment delivery to the seafloor.

References: Behr and Becker, 2018. Sediment control on subduction plate speeds, Earth and Planetary Science Letters Behr et al., 2018. Dehydration-induced rheological heterogeneity and the deep tremor source in warm subduction zones, Geology