Deglacial and postglacial paleoseismological archives in mass-movement deposits of lakes of south-central Québec.

Trottier, Annie-Pier; Lajeunesse, Patrick; Normandeau, Alexandre et Gagnon-Poiré, Antoine (2019). Deglacial and postglacial paleoseismological archives in mass-movement deposits of lakes of south-central Québec. Canadian Journal of Earth Sciences / Revue canadienne des sciences de la Terre , vol. 56 , nº 1. pp. 60-76. DOI: 10.1139/cjes-2018-0167.

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Résumé

Investigation of seismic activity in eastern Canada is important for natural hazard management since two major active seismic zones with many historical records are located in the region: the Western Québec and the Charlevoix-Kamouraska seismic zones, with the latter being the most active in northeastern America. This paper describes and analyses a dataset of high-resolution swath bathymetric imagery, sub-bottom profiles and sediments cores collected in three lakes (Maskinongé, Aux-Sables and St-Joseph) located between two active seismic zones. The geomorphology observed on high-resolution swath bathymetric imagery, the acoustic sub-bottom profiles and the sediment analysis indicate that the lakes were disturbed by three phases of seismically-induced mass-movements since deglaciation : 1) during the deglacial Champlain Sea transgression and the rapid initial glacio-isostatic rebound between ~13 and 10.5 ka cal. BP; 2) around 1180 AD; and 3) the well documented CKSZ 1663 AD M>7 historical earthquake. The second phase of earthquake events (1180 AD) corresponds chronologically to a previously documented large-landslide in western Québec, dated at ~1020 yr BP. This earthquake is responsible for remobilizing the largest volume of sediments in the entire stratigraphic sequence of Lake Maskinongé, the westernmost lake. This earthquake was not recorded in Lake Aux-Sables and St-Joseph, which are located eastward from Maskinongé, but the largest MMDs are associated with the well-known 1663 AD event of eastern Québec. Therefore, both earthquake events are interpreted to have different epicenters and the lakes of southeastern Québec recorded earthquakes from both seismic zones.

Type de document:	Article
Mots-clés libres:	mass-movement deposits; earthquakes; lakes; geomorphology; stratigraphy
Centre:	Centre Eau Terre Environnement
Date de dépôt:	18 oct. 2018 19:16
Dernière modification:	10 mai 2021 15:34
URI:	https://espace.inrs.ca/id/eprint/7665

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