6533b7d6fe1ef96bd12670fb

RESEARCH PRODUCT

Benchmarking numerical models of brittle thrust wedges

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International audience; We report quantitative results from three brittle thrust wedge experiments, comparing numerical resultsdirectly with each other and with corresponding analogue results. We first test whether the participatingcodes reproduce predictions from analytical critical taper theory. Eleven codes pass the stable wedgetest, showing negligible internal deformation and maintaining the initial surface slope upon horizontaltranslation over a frictional interface. Eight codes participated in the unstable wedge test that examinesthe evolution of a wedge by thrust formation from a subcritical state to the critical taper geometry. Thecritical taper is recovered, but the models show two deformation modes characterised by either mainlyforward dipping thrusts or a series of thrust pop-ups. We speculate that the two modes are caused bydifferences in effective basal boundary friction related to different algorithms for modelling boundaryfriction. The third experiment examines stacking of forward thrusts that are translated upward along abackward thrust. The results of the seven codes that run this experiment show variability in deformationstyle, number of thrusts, thrust dip angles and surface slope. Overall, our experiments show that nu-merical models run with different numerical techniques can successfully simulate laboratory brittlethrust wedge models at the cm-scale. In more detail, however, we find that it is challenging to reproducesandbox-type setups numerically, because of frictional boundary conditions and velocity discontinuities.We recommend that future numerical-analogue comparisons use simple boundary conditions and thatthe numerical Earth Science community de fines a plasticity test to resolve the variability in model shearzones