Numerical models of thermally activated convective flow in Earth's mantle do not resemble active plate tectonics because of their inability to model successfully the process of subduction, other than by the inclusion of artificial weak zones. Here we show, using a boundary layer argument, how the "rigid lid" style of convection favored by thermoviscous fluids leads to lithospheric stresses whic...

Although the morphologies of subducting slabs have been relatively well characterized, the character of the mantle flow field that accompanies subduction remains poorly understood. To analyze this pattern of flow, we compiled observations of seismic anisotropy, as manifested by shear wave splitting. Data from 13 subduction zones reveal systematic variations in both mantle-wedge and subslab anis...

[1] For episodic slow slip transients in subduction zones, a large uncertainty in comparing surface deformations predicted by forward modeling based on rate and state friction to GPS measurements lies in our limited knowledge of the frictional properties and fluid pore pressure along shallow subduction faults. In this study, we apply the laboratory rate and state friction data of granite and ga...

We develop a predictive model which has the ability to explain a postulated style of episodic plate tectonics on Venus, through the periodic occurrence of lithospheric subduction events. Present-day incipient subduction zones are associated with the existence of arcuate trenches on the Venusian lithosphere. These trenches resemble terrestrial subduction zones, and occur at the rim of coronae, u...

A simple model for necking and detachment of subducting slabs is developed to include the coupling between grain-sensitive rheology and grain-size evolution with damage. Necking is triggered by thickened buoyant crust entrained into a subduction zone, in which case grain damage accelerates necking and allows for relatively rapid slab detachment, i.e., within 1 My, depending on the size of the c...

Density-driven sinking velocity Density-driven sinking velocity Slab-dip angle Plate-advance velocity Subduction-retreat velocity Subduction-retreat velocity Overriding slab Subducting slab transformations at 400–700 km down. The authors identify four central points. First, subducted material sinks at a velocity that is controlled solely by its negative buoyancy and the viscosity of the surroun...

Candidate models of the forces which oppose the sinking of slabs are all constrained to produce results consistent with the following observation: relative geoid highs, which one assumes are due to slabs, characteristically occur over subduction zones. Certain models which are otherwise plausible, such as those based on a Newtonian half-space mantle, yield geoid lows instead of highs. This stud...

S U M M A R Y The wavelet approach to numerical simulation of elastic wave propagation is applied to models with localized heterogeneity, with significant contrasts with their surroundings. We consider zones with both lowered wave speed such as a fault gouge zone and elevated wave speeds such as in a subduction zone. In each of these situations the source lies within the heterogeneity. The repr...

[1] We analyze short-period precursory energy to PP that can be observed in seismograms in the distance range from 95 to 105 to infer the behavior of subducted slabs beneath western Pacific subduction zones. PP is a P wave once reflected at the free surface between the source and receiver. Using high-resolution seismic array techniques, we analyze the incidence angle, timing, and azimuth of the...

We investigate the dehydration processes in subduction zones and their implications for the water cycle throughout Earth's history. We use a numerical tool that combines thermo-mechanical models with a thermodynamic database to examine slab dehydration for present-day and early Earth settings and its consequences for the deep water recycling. We investigate the reactions responsible for releasi...