Development and potential triggering mechanisms for a large holocene landslide in the lower st. Lawrence estuary

Abstract

The Betsiamites 7,250 cal BP submarine landslide mobilized a volume of 1.3 km3 in the St. Lawrence Estuary, Eastern Canada. The failure was initiated in shallow water between 10 and 140 mbsl and most likely developed in a unit stratified clayey silt deposits following a very strong earthquake. Most of the failed mass appears dislocated and evacuated the failure source area. This paper concludes that gas hydrates dissociation could not have influenced slope stability on the shelves of the Lower St. Lawrence Estuary in the Early Holocene and that despite the high sedimentation rates prior to the failure this condition did not act independently as a significant trigger for the Betsiamites failure. © Springer Science+Business Media B.V. 2012.