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Subduction zone slip variability during the last millennium, south-central Chile


Tina Dura, Benjamin Horton, Marco Cisternas, Lisa Ely, Isabel Hong, Alan Nelson, Robert Wesson, Jessica Pilarczyk, Andrew Parnell, Daria Nikitina

Publication Type: 
Refereed Original Article
The Arauco Peninsula (37-38S) in south-central Chile has been proposed as a possible barrier to the along-strike propagation of megathrust ruptures, separating historical earthquakes to the south (1960 AD 1837, 1737, and 1575) and north (2010 AD, 1835, 1751, 1657, and 1570) of the peninsula. However, the 2010 (Mw 8.8) earthquake propagated into the Arauco Peninsula, re-rupturing part of the megathrust that had ruptured only 50 years earlier during the largest subduction zone earthquake in the instrumental record (Mw 9.5). To better understand long-term slip variability in the Arauco Peninsula region, we analyzed four coastal sedimentary sections from two sites (TirĂșa, 38.3S and Quidico, 38.1S) located within the overlap of the 2010 and 1960 ruptures to reconstruct a ~600-year record of coseismic landlevel change and tsunami inundation. Stratigraphic, lithologic, and diatom results show variable coseismic land-level change coincident with tsunami inundation of the TirĂșa and Quidico marshes that is consistent with regional historical accounts of coseismic subsidence during earthquakes along the Valdivia portion of the subduction zone (1960 AD and 1575) and coseismic uplift during earthquakes along the Maule portion of the subduction zone (2010 AD, 1835, 1751). In addition, we document variable coseismic land-level change associated with three new prehistoric earthquakes and accompanying tsunamis in 1470e1570 AD, 1425e1455, and 270e410. The mixed record of coseismic subsidence and uplift that we document illustrates the variability of down-dip and lateral slip distribution at the overlap of the 2010 and 1960 ruptures, showing that ruptures have repeatedly propagated into, but not through the Arauco Peninsula and suggesting the area has persisted as a long-term impediment to slip through at least seven of the last megathrust earthquakes (~600 years)
Digital Object Identifer (DOI): 
Publication Status: 
Date Accepted for Publication: 
Friday, 25 August, 2017
Publication Date: 
Quaternary Science Reviews Volume 175, 1 November 2017, Pages 112-137
National University of Ireland, Dublin (UCD)
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