Seismotectonic and stress distribution in the central Chile subduction zone

摘要: Abstract We determined the stress tensor from focal mechanisms and shape of downgoing Nazca Plate subducted beneath central Chile (26–35°S), based on accurately located hypocenters local teleseismic events, at three different segments defined by rupture zones great thrust earthquakes. Between latitudes 26–33°S slab flattens intermediate depths moves upwards probably related to subduction buoyant lithosphere associated Juan Fernandez Ridge (JFR). To south is steeper penetrates into mantle with a constant dip 27° implying sharp change around 33°S. The seismicity reaches maximum depth 200 km 29°S while north deep observed 570–630 km, gap between these depths. A remarkable along-strike variation in seismic length 1100 km 29°S, 800 km 30 32°S 350 km suggests thick oceanic crust JFR subduction, furthermore this more intense moment released than adjacent zones. tensors show differences steep flat zones, being important where flattens. At shallow compressive due plate convergence. under tensional regime, pull zone also forces zone. interplate coupling South American Plates 60 km, similar other places along Chilean