Decadal-scale postseismic deformation of subduction earthquakes has been widely modeled using a Maxwell viscoelastic Earth with a mantle-wedge viscosity of about 10^19 Pa s. Short-term postseismic deformation within a few years after the earthquake remains a more challenging problem because of the predominance of afterslip of the megathrust and the potentially more complex mantle rheology. Questions include the necessity of invoking the transient rheology and the relative importance of contributions from afterslip and viscoelastic relaxation. Primary observational constraints for the short-term postseismic deformation include 1 year net displacements of nine near-field
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Basal erosion is a prevalent process at subduction zones and plays an important role in the mass balance of global plate tectonics. In contradiction with the theoretical expectation that basal erosion requires high basal friction and hence compression in the upper plate, extensional faulting is commonly observed in submarine wedges that undergo such erosion. Here we propose a model to explain this apparent paradox in terms of stress fluctuations during earthquake cycles. In this model, basal erosion occurs during large earthquakes when the shallow, rate-strengthening part of the plate interface strengthens and its overlying wedge weakens, but extension occurs during inters
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Temporary deformation in great earthquake cycles and permanent shear deformation associated with oblique plate convergence both provide critical clues for understanding geodynamics and earthquake hazard at subduction zones. In the region affected by the Mw 9.5 great Chile earthquake of 1960, we have obtained GPS observations that provide information on both types of deformation. The new observations revealed a pattern of opposing (roughly arc-normal) motion of coastal and inland sites, consistent with what was reported earlier for the northern part of this region. The new observations also provide the first geodetic evidence for the dextral motion of an intravolcanic arc
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