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Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract: At least three major landslide events formed the submarine and subaerial Betsiamites (Québec, Canada) landslide complex and mobilized an estimated total volume of 2000million m3 (2km3). Linkage between offshore and onshore geophysical investigations with borehole data and in situ testing allows reconstruction of the architecture of the Betsiamites River delta area and leads to the identification of the main failure events. The submarine scar of the Betsiamites landslide complex may have resulted from a first failure, dated at about 9250cal BP, which mobilized a minimum volume of 200million m3. A second landslide dated at 7250cal BP mobilized a volume of 1300million m3 over an area of 54km2. The Betsiamites submarine landslide event dated at 7250cal BP left the largest scar yet identified on the St. Lawrence estuary seafloor. Furthermore, this paper demonstrates that the subaerial scar of the Betsiamites landslide complex is a result of the Colombier landslide event, which was initiated by the 1663 earthquake and involved four successive failure phases: one submarine and three subaerial. The February 5th 1663 earthquake triggered a submarine landslide event, which reached the shoreline, and led in a short period of time successively to two subaerial flowslides in sensitive clayey material and a subaerial lateral spread. The four failure phases mobilized a possible total volume of about 530million m3 over an area of 20km2. The Colombier landslide event is among the largest documented historic landslides in Canada. The presence of submarine scars left by the early Holocene events acted as predisposition factors for the development of the failure while the earthquake of 1663 was the main triggering factor of the first submarine failure. [Copyright &y& Elsevier]

Using some new and previously published sedimentation rate data the relationship between sedimentation rate and distance from sediment source was statistically modelled for the Saguenay Fjord, Canada. Sedimentation rates obtained from these models can be used to reasonably predict the range of ages for submarine mass movements in the Saguenay Fjord. Error in the prediction is mostly associated with the natural variability of sedimentation rate. Ranges of dates were predicted for several submarine mass movements in the Upper Saguenay Fjord. In many cases the predicted date range did not correspond to the 1663 earthquake which had been previously assumed to have triggered these mass movements. [ABSTRACT FROM AUTHOR]