盒子内的冲击:俯冲地震周期的模拟模型应用于地震构造的弧前演化
We introduce and test an experimental approach to simulate elastoplastic megathrustearthquake cycles using an analogue model and apply it to study the seismotectonicevolution of subduction zones. The quasi-two-dimensional analogue model featuresrate- and state-dependent elastic-frictional plastic and viscoelastic material properties andis scaled for gravity, inertia, elasticity, friction, and viscosity. The experiments aremonitored with a high-resolution strain analysis tool based on digital image correlation(particle imaging velocimetry, PIV), providing deformation time series comparable toseismologic, geodetic, and geologic observations. In order to separate elastic andnonelastic effects inherent the experimental deformation patterns, we integrate elasticdislocation modeling (EDM) into a hybrid approach: we use the analogue earthquake slipand interseismic locking distribution as EDM dislocation input and forward model thecoseismic and interseismic elastic response. The residual, which remains when the EDMprediction is subtracted from the experimental deformation pattern, highlights theaccumulation of permanent deformation in the model. The setup generates analogueearthquake sequences with realistic source mechanisms and elastic forearc response andrecurrence patterns and reproduces principal earthquake scaling relations. By applyingthe model to an accretionary-type plate margin, we demonstrate how strain localization atthe rupture peripheries may lead to a seismotectonically segmented forearc, including atectonically stable shelf and coastal high (20% plate convergence accommodated byinternal shortening) overlying the area of large megathrust earthquake slip. Fifty to 75% ofplate convergence is accommodated by internal shortening in the slope region whereearthquake slip tapers out toward the trench. The inner forearc region remains undeformedand represents a basin.