Predecessors of the giant 1960 Chile earthquake

Abstract

It is commonly thought that the longer the time since last earthquake, the larger the next earthquake's slip will be. But this logical predictor of earthquake size, unsuccessful for large earthquakes on a strike-slip fault, fails also with the giant 1960 Chile earthquake of magnitude 9.5 (ref. 3). Although the time since the preceding earthquake spanned 123 years (refs 4, 5), the estimated slip in 1960, which occurred on a fault between the Nazca and South American tectonic plates, equalled 250-350 years' worth of the plate motion. Thus the average interval between such giant earthquakes on this fault should span several centuries. Here we present evidence that such long intervals were indeed typical of the last two millennia. We use buried soils and sand layers as records of tectonic subsidence and tsunami inundation at an estuary midway along the 1960 rupture. In these records, the 1960 earthquake ended a recurrence interval that had begun almost four centuries before, with an earthquake documented by Spanish conquistadors in 1575. 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.

Forearc uplift rates deduced from sediment cores of two coastal lakes in south-central Chile

“…Moernaut et al, 2007;Bertrand et al, 2008;Blumberg et al, 2008), and secondary implications (e.g. tsunamis, Cisternas et al, 2005). In this study, we focus on the first mentioned aspect and evaluate the sediments of Lago Lanalhue and Lago Lleu Lleu concerning their potential of recording local forearc deformation.…”

Investigating subduction earthquake geology along the southern Hikurangi margin using palaeoenvironmental histories of intertidal inlets

“…Nelson et al 1996;Clague 1997;Cisternas et al 2005). Supporting evidence may include liquefaction of sediments and landsliding.…”

“…Globally, almost all palaeoseismic records of subduction earthquakes have been obtained from the coastal zone (e.g. Atwater 1987;Darienzo et al 1994;HemphillÁHaley 1995;Nelson et al 1996Nelson et al , 2006Zachariasen et al 1999;Sawai et al 2002;Nanayama et al 2003;Cisternas et al 2005;Melnick et al 2006;Rajendran et al 2008). Within the coastal zone, sea level can be used as a benchmark against which uplift and subsidence of the upper plate due to subduction earthquake deformation can be measured.…”

Interseismic strain accumulation and the earthquake potential on the southern San Andreas fault system

“…This may be compared to paleoseismologic estimates of average recurrence times of large events on the southern SAF of 200-300 years, and average coseismic displacements of 4 to 7 meters 1,2 . Although simple time-and size-predictable earthquake models have been shown to be inadequate [30][31][32] , and the repeat interval between large earthquakes may vary significantly, it may be argued that the accumulated slip deficit cannot greatly exceed the maximum coseismic offset documented throughout the fault history. If so, the southern SAF is likely in the late phase of its interseismic recurrence 2,7,9 .…”