Last night an 8.3 magnitude earthquake struck Chile. It happened along a convergent boundary where the Nazca plate is moving towards South America at a rate of 74 mm/year, subducting under the South American plate. This subduction zone is prone to earthquakes - in the last century there have been over 15 earthquakes with a magnitude greater than 7 here, and the strongest recorded earthquake, with a magintude of 9.5, was recorded in the zone in 1960. You can read the full tectonic summary from the U.S. Geological Survey (USGS) here: http://earthquake.usgs.gov/earthquakes/eventpage/us20003k7a#general_summary