A new seismic model of the three-dimensional variation in shear velocity throughout the Earth's mantle is presented. The model is derived entirely from shear bodywave travel times. Multibounce shear waves, core-reflected waves and SKS and SKKS waves that travel through the core are used in the analysis. A unique aspect of the dataset used in this study is the use of bodywaves that turn at shall...

[1] Shear-wave splitting observations from many subduction zones show complex patterns of seismic anisotropy that commonly have trench-parallel fast directions. Three-dimensional flow may give rise to trench-parallel stretching and provide an explanation for these patterns of seismic anisotropy. Along-strike variations in slab geometry produce trench-parallel pressure gradients and are therefor...

Exhumation has been recognized as an important problem in tectonics and can be achieved by normal faulting, ductile thinning, and erosion. The exhumation of ultrahigh-pressure (UHP) rocks is the most challenging and least understood aspect of the exhumation problem. In this review, we focus on a variety of geologic settings with the goal of characterizing exhumation rates and maximum depths of ...

[1] We present three‐dimensional laboratory modeling of the evolution of finite strain and compare these to shear wave splitting observations in the Northwest U.S. under the High Lava Plains (HLP). We show that relationships between mantle flow and anisotropy are complicated in subduction zones and factors such as initial orientation of the olivine fast‐axis, style of subduction, and time evolv...

Plate subduction continuously transports crustal materials with high-δ(18)O values down to the mantle wedge, where mantle peridotites are expected to achieve the high-δ(18)O features. Elevated δ(18)O values relative to the upper mantle value have been reported for magmas from some subduction zones. However, peridotites with δ(18)O values significantly higher than the well-defined upper mantle v...

[1] To investigate the possible physical mechanisms of recently observed aseismic slip events in the Cascadia, Japan and Mexico subduction zones, we apply a Dieterich-Ruina rate and state friction law to a three dimensional model of a shallow subduction fault. That is loaded by imposed steady plate slip rate far downdip along the thrust interface. Friction properties are temperature and hence d...