The Chilean continental margin is one of the most seismically active subduction systems and serves as a natural laboratory to study mega-thrust earthquakes. We present results of the active seismic reflection survey of project TIPTEQ (from The Incoming Plate to mega-Thrust EarthQuake processes), which covers the subduction zone in southern central Chile in the area of the 1960 Valdivia earthquake hypocentre. The application of Kirchhoff prestack depth migration as well as two advanced imaging techniques (FVM, RIS) reveal a clear image of the subducted oceanic Nazca plate from the coast down to a depth of about 50 km below the Central Valley. The overriding continental crust is strongly structured showing horizontal, dipping and arching reflectors that indicate basal accretion. The reflectivity varies across the section and appears to be weak around the area of the 1960 earthquake hypocentre. Other specific features can be observed, like for instance a possible subduction channel at the top of the oceanic plate near the coast, a major crustal fault zone (LFZ) as well as a strong west dipping reflector perpendicular to the plate interface. In this paper we combine the high resolution seismic image with results from other geophysical disciplines to give a detailed picture of the Chilean subduction zone at 38° S.
AGU Fall Meeting Abstracts
- Pub Date:
- December 2007
- 7230 Seismicity and tectonics (1207;
- 7240 Subduction zones (1207;
- 8170 Subduction zone processes (1031;