ABSTRACT: The Pointe-du-Fort mass movement deposits, Upper Saguenay Fjord, Canada: a multiphase build-up.

CGRG Bibliography of Canadian Geomorphology
Search Results

Author :

Date :

Title :

Publication :

Issue :

Page(s) :

Abstract

The Upper Saguenay Fjord, Canada, has been struck in the last ˜400 yrs, by various natural disasters including earthquakes, landslides and flash floods. Because of these events, many research projects have been carried out in this area during the last decades to improve the state of knowledge on natural hazards processes. As a contribution to the understanding of submarine mass movements behaviour from the crown to the toe, a small portion of the geological panorama of this region, the Pointe-du-Fort area, has been chosen. Its small size has helped to overcome the scale characterization problems often encounter within the study of larger submarine slides and has permit-tedto understand more easily the behaviour of the failed mass. The Pointe-du-Fortdeposits have been previously interpreted as the result of a single sedimentation event triggered by the 1663 Ms˜7 Charlevoix earthquake. Some authors have proposed that these deposits represent the spread of a failed mass coming from the south fjord wall. The different data sets (i.e. multibeam coverage, seismic profiles and CAT-scan imagery) have shown evidences revealing that the Pointe-du-Fort deposits are the result of a multiphase build-up instead of a spread. Nine phases were documented. These phases include many episodes of erosion and sedimentation by debris flows. Four ofthe nine phases were confined within channels and the next to last phase corresponds to the slope re-equilibration. These sedimentary processes were induced by bottom slope erosion caused by the passage of a major debris flow coming upstream from the surveyed area, which was previously triggered by the 1663 Ms˜7 earthquake.

Bibliography of Canadian Geomorphology