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https://doi.org/10.5194/egusphere-2024-8
https://doi.org/10.5194/egusphere-2024-8
20 Feb 2024
 | 20 Feb 2024

Co- and postseismic subaquatic evidence for prehistoric fault activity near Coyhaique, Aysén Region, Chile

Morgan Vervoort, Katleen Wils, Kris Vanneste, Roberto Urrutia, Mario Pino, Catherine Kissel, Marc De Batist, and Maarten Van Daele

Abstract. Chilean Patagonia is confronted with several geohazards due to its tectonic setting, i.e., the presence of a subduction zone and numerous fault zones (e.g. the Liquiñe-Ofqui Fault Zone). This region has therefore been the subject of numerous paleoseismological studies. However, this study reveals that the seismic hazard is not limited to these large tectonic structures by identifying past fault activity near Coyhaique in the Aysén Region. Mass wasting deposits in Lago Pollux, a lake located ca. 15 km SW of this region’s capital, were identified through analysis of reflection-seismic data and was linked to a simultaneous event recorded in nearby Lago Castor. Furthermore, a coeval ~50 year-long catchment response was identified in Aysén Fjord based on the multiproxy analysis of a portion of a sediment core. Assuming that this widely recognized event was triggered by an earthquake, ground-motion modelling was applied to derive the most likely magnitude and source fault. The model showed that an earthquake rupture along a local fault, in the vicinity of Lago Pollux and Lago Castor, with a magnitude of 5.6–6.8, is the most likely scenario.

Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this preprint. The responsibility to include appropriate place names lies with the authors.
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Journal article(s) based on this preprint

07 Oct 2024
Co- and postseismic subaquatic evidence for prehistoric fault activity near Coyhaique, Aysén Region, Chile
Morgan Vervoort, Katleen Wils, Kris Vanneste, Roberto Urrutia, Mario Pino, Catherine Kissel, Marc De Batist, and Maarten Van Daele
Nat. Hazards Earth Syst. Sci., 24, 3401–3421, https://doi.org/10.5194/nhess-24-3401-2024,https://doi.org/10.5194/nhess-24-3401-2024, 2024
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.

Short summary
This study identified a prehistoric earthquake around 4400 years ago near the city of Coyhaique...
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