| Titre | Crustal motion in the zone of the 1960 Chile earthquake: Detangling earthquake-cycle deformation and forearc-sliver translation |
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| Auteur | Wang, K ; Hu, Y;
Bevis, M; Kendrick, E; Smalley, R, Jr.; Vargas, R B; Lauria, E |
| Source | Geochemistry, Geophysics, Geosystems (G3) vol. 8, no. 10, 2007, 14p., https://doi.org/10.1029/2007GC001721  Accès ouvert |
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| Année | 2007 |
| Séries alt. | Secteur des sciences de la Terre, Contribution externe 20070241 |
| Éditeur | Wiley-Blackwell |
| Document | publication en série |
| Lang. | anglais |
| DOI | https://doi.org/10.1029/2007GC001721 |
| Media | en ligne; numérique |
| Formats | pdf |
| Lat/Long OENS | -76.0000 -72.0000 -37.0000 -46.0000 |
| Sujets | secousses séismiques; déformation; détermination des contraintes; contrainte de cisaillement; zones de subduction; subduction; mouvements de la croûte; études de la croûte; failles; failles
transformantes; Zone de faille de Liquine-Ofqui ; géophysique; tectonique; géologie structurale |
| Illustrations | croquis cartographiques; blocs-diagrammes |
| Programme | Réduction des risques dus aux aléas naturels |
| Diffusé | 2007 10 18 |
| Résumé | (disponible en anglais seulement)
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. Our velocity solutions
for the first time span the entire latitudinal range of the 1960 earthquake. 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. This finding supports the model of prolonged postseismic deformation as a result of viscoelastic stress relaxation in the mantle. The new observations also provide the first geodetic evidence for the dextral motion of an
intra-volcanic arc fault system and the consequent northward translation of a forearc sliver. The silver motion can be modeled using a rate of 6.5 mm/yr, accommodating about 75% of the margin-parallel component of Nazca—South America relative plate
motion, with the rate diminishing to the north. Furthermore, the new GPS observations show a southward decrease in margin-normal velocities of the coastal area. We prefer explaining the southward decrease in terms of changes in the frictional
properties of the megathrust seismogenic zone. Because of the much younger age of the subducting plate and warmer thermal regime in the south, the currently locked portion of the plate interface may be narrower. Using a three-dimensional viscoelastic
finite element model of postseismic and interseismic deformation following the 1960 earthquake, we demonstrate that this explanation, although not unique, is consistent with the GPS observations to the first order. |
| GEOSCAN ID | 224241 |
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