Central Chile Finally Breaks

Abstract

Chile is the site of some of the largest earthquakes in the world: On average, a magnitude 8 earthquake occurs there every 10 years or so. These earthquakes take place in the subduction zone, either as interplate ruptures at the interface between the South American and Nazca plates or as intraplate events within the subducted Nazca plate. A few times in every century, massive plate-interface earthquakes break several hundred kilometers in a single shock. This is what happened on 27 February 2010, when a major earthquake (magnitude 8.8) occurred in the Maule and Biobío regions in central Chile (see the first figure). This region had last experienced a major subduction earthquake in 1835, when Darwin (1) visited the area as part of his voyage on the Beagle. His description of the earthquake inspired many seismologists and historians of Chilean earthquakes (2, 3).