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TitleThermal control of the seismogenic zone of southern central Chile
AuthorVolker, D; Grevemeyer, I; Stipp, M; Wang, K; He, J
SourceJournal of Geophysical Research vol. 116, B10305, 2011 p. 1-20, (Open Access)
Alt SeriesEarth Sciences Sector, Contribution Series 20110069
Mediapaper; on-line; digital
File formatpdf
Lat/Long WENS-78.0000 -70.0000 -36.0000 -44.0000
Subjectsgeophysics; tectonics; subduction zones; subduction; seismicity; thermal regimes; Chile Ridge; Nazca Plate; Chile Trench
Illustrationslocation maps; tables; plots; profiles
ProgramTargeted Hazard Assessments in Western Canada, Public Safety Geoscience
Released2011 10 13
AbstractWe 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.