Article Dans Une Revue Depositional Record Année : 2025

A continuous 500‐year sediment record of inundation by local and distant tsunamis in South‐Central Chile (40.1°S)

Résumé

Abstract Chile's west coast is frequently struck by megathrust earthquakes and tsunamis, as illustrated by the CE 2010 Maule ( M w 8.8) and CE 1960 Valdivia ( M w 9.5) events. Despite numerous palaeoseismic and palaeotsunami studies, uncertainties remain regarding the rupture extent and tsunamigenic potential of M w 8–9 earthquakes. This study examines the sedimentary record of Laguna Gemela West, a coastal lake at 5–6 m a.s.l. and of 17.5 m depth. It is separated from the Pacific by a 400 m long channel bordered by northward‐propagating dunes and controlled by Pleistocene sandstones forming a knickpoint in the channel profile. Multiple sedimentary proxies (e.g. grain‐size, X‐CT, XRF scanning) identified five distinct sand‐enriched layers, interpreted as tsunami deposits. Age‐depth modelling (based on 137Cs and 14C) allowed linking these deposits to the CE 2010, 1960, 1837, 1737 and 1575 megathrust earthquakes. While historical records confirm significant tsunamis in CE 2010, 1960, 1837 and 1575, no reports exist for a CE 1737 tsunami. However, a potential tsunami deposit and evidence for subsidence were found at the nearby Chaihuín site, albeit with large dating uncertainty (CE 1600–1820). The more precise age for a sand layer at Laguna Gemela West (CE 1672–1746) supports the occurrence of a local tsunami in CE 1737. Additionally, deposits linked to the CE 1837 and 2010 events suggest tsunamis can impact sites >100 km adjacent to megathrust ruptures. A second pulse in the uppermost sand layer may reflect the CE 2011 Japan tsunami, which reached a similar height (~1.6 m a.s.l.) in the nearest tide gauge as the CE 2010 tsunami. Unlike coastal plain sites, which often require coseismic subsidence for deposit preservation, coastal lakes can capture a more complete tsunami history. This study highlights their complementary role in palaeotsunami research, providing insights in local, regional and transoceanic tsunami events.

Fichier principal
Vignette du fichier
The Depositional Record - 2025 - Moernaut - A continuous 500‐year sediment record of inundation by local and distant.pdf (6.05 Mo) Télécharger le fichier
Origine Fichiers éditeurs autorisés sur une archive ouverte
Licence

Dates et versions

hal-05190714 , version 1 (29-07-2025)

Licence

Identifiants

Citer

Jasper Moernaut, Evelien Boes, Daniel Melnick, Matías Carvajal, Markus Niederstätter, et al.. A continuous 500‐year sediment record of inundation by local and distant tsunamis in South‐Central Chile (40.1°S). Depositional Record, 2025, ⟨10.1002/dep2.70031⟩. ⟨hal-05190714⟩
68 Consultations
120 Téléchargements

Altmetric

Partager

  • More