Although the time since the preceding earthquake spanned 123 years, the estimated slip in 1960 Chile earthquake, which occurred on a fault between the Nazca and South American tectonic plates, equalled 250-350 years a worth of the plate motion. Geological record shows that the penultimate event occurred during 1575, and the average interval between giant earthquakes on this fault spanned 300 years. Two later earthquakes, in 1737 and 1837, produced little, if any, subsidence or tsunami at the estuary and they therefore probably left the fault partly loaded with accumulated plate motion that the 1960 earthquake then expended.