The earthquake occurred along a 500 - kilometre segment of the Peru - Chile subductionzone, where part of the Nazca Plate in the Pacific Ocean plunges beneath the South American Plate.
The great Sumatra - Andaman earthquake of Dec. 26, 2004, for instance, unzipped a 1,300 kilometer long segment of the subductionzone and unleashed one of history's most destructive, deadly tsunamis.