| Titre | Coseismic strengthening of the shallow portion of the subduction fault and its effects on wedge taper |
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| Auteur | Hu, Y; Wang, K |
| Source | Journal of Geophysical Research vol. 113, B12411, 2008, 14p., https://doi.org/10.1029/2008JB005724 |
| Image |  |
| Année | 2008 |
| Séries alt. | Secteur des sciences de la Terre, Contribution externe 20080281 |
| Éditeur | Wiley-Blackwell |
| Document | publication en série |
| Lang. | anglais |
| DOI | https://doi.org/10.1029/2008JB005724 |
| Media | papier; en ligne; numérique |
| Formats | pdf |
| Sujets | subduction; zones de subduction; mécanismes de tremblement de terre; secousses séismiques; études séismiques; modèles; modèles de la croûte; modèles sismiques; zones de failles; établissement de modèles;
détermination des contraintes; tectonique |
| Illustrations | graphiques; coupes transversales |
| Programme | Réduction des risques dus aux aléas naturels |
| Diffusé | 2008 12 23 |
| Résumé | (disponible en anglais seulement)
According to the dynamic Coulomb wedge model, it is mainly the coseismic strengthening of the shallowest part of the subduction interface that is responsible
for the permanent deformation of the overlying outer wedge. In this work, we use a numerical model, which is a hybrid of the frictional contact model and the classical crack model, to study how stress is coseismically transferred from the seismogenic
zone to the strengthening updip zone to cause wedge deformation. In this model, the "critical strengthening" required to prevent the rupture from breaking the trench depends on the force drop of the seismogenic zone, defined as the product of the
average shear stress drop and the area of the seismogenic zone. In a simple model of uniform material properties with a few MPa average stress drop over a seismogenic zone of 120 km downdip width, the critical strengthening for a 30 km wide updip
zone is an increase in the effective friction coefficient by about 0.05. Using the Coulomb wedge theory, we demonstrate that this level of strengthening can readily push the overlying wedge into a critical state of failure. With much greater
strengthening, the rupture is able to propagate into the updip zone only slightly, causing localized wedge compression in the area of slip termination. We examined wedge geometry of twenty-three subduction zones in the light of the model results. We
found that the surface slope of these wedges is generally too high to be explained using the classical wedge theory but can be explained using the dynamic Coulomb wedge model including coseismic strengthening of the shallow portion of the
megathrust. |
| GEOSCAN ID | 225588 |
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