But it wasn't, says Lorito. His team used data on how the surface moved during the 2010 quake -- from geodetic markers and tsunami observations, among others -- to calculate which parts slipped the most.
The scientists found that the greatest slip occurred north of the quake's epicenter, right around where the 1928 quake struck. South of the epicenter lay a secondary zone of slip. But right in the middle, where the Darwin gap lies, was little to no movement. "The Darwin gap is still there," Lorito says.
Other earthquake zones, such as Sumatra in 2007, have experienced big quakes that didn't relieve pent-up geologic stress where scientists thought it was greatest. "It is not strange to see that the rupture is complex, and that some parts can break at one time and some at another time," Lorito says.
The new work fits with several other scenarios that scientists have developed to explain ground movement during the Chile quake. The scenarios, however, differ in their details. For example, researchers from the GFZ German Research Center for Geosciences in Potsdam reported in Nature in September 2010 that some of the quake's slip happened fairly close to the Darwin gap.