GEOSCAN, résultats de la recherche


TitreThermal control of the seismogenic zone of southern central Chile
AuteurVolker, D; Grevemeyer, I; Stipp, M; Wang, K; He, J
SourceJournal of Geophysical Research vol. 116, B10305, 2011 p. 1-20,
Séries alt.Secteur des sciences de la Terre, Contribution externe 20110069
Documentpublication en série
Mediapapier; en ligne; numérique
Lat/Long OENS-78.0000 -70.0000 -36.0000 -44.0000
Sujetszones de subduction; subduction; sismicité; regimes thermiques; Plaque de Nazca ; géophysique; tectonique
Illustrationslocation maps; tables; plots; profiles
ProgrammeTargeted Hazard Assessments in Western Canada, Géoscience pour la sécurité publique
Résumé(disponible en anglais seulement)
We developed thermal models for the Chile subduction zone along two profiles at 38.2°S and 42°S within the rupture area of the 1960 M = 9.5 Valdivia earthquake and south of the 2010 M = 8.8 Maule earthquake. The age difference of the subducting Nazca Plate has a major impact on the thermal regime, being much younger and hotter in the south. Seafloor heat flow observations confirm this difference but also indicate that in the southern area, heat advection at the outer rise cools the incoming plate. Heat flow values derived from the depth of gas hydrate bottom?simulating reflectors are in general agreement with probe and borehole measurements. The positions where the plate interface reaches temperatures of 100 - 150°C and 350 - 450°C differ between the two profiles. If these temperatures control the updip and downdip limits of the interplate seismogenic zone, the seismogenic zone widens and shifts landward to greater depths from south to north. Observed microseismicity, however, seems to fade at temperatures much lower than 350 - 450°C. This discrepancy can be explained in three alternative ways: (1) deformation in a thick subduction channel controls the seismic/aseismic transition; (2) microseismicity recorded over a limited time period does not represent the rupture depth of large interface earthquakes; or (3) the serpentinized mantle wedge controls the downdip limit.