Large-scale seismically-induced mass-movements in a former glacial lake basin: Lake Temiscouata, northeastern Appalachians (eastern Canada)

作者：Lajeunesse Patrick^*; Sinkunas Bryan; Morissette Antoine; Normandeau Alexandre; Joyal Gabriel; St Onge Guillaume; Locat Jacques

来源：Marine Geology, 2017, 384: 120-130.

DOI：10.1016/j.margeo.2016.04.007

• Mass movements
• Paleoseismicity
• Natural hazards
• Multibeam bathymeby
• Limnogeology

Disturbed lacustrine deposits of eastern Canada have been associated with past seismic events in the intraplate Western Quebec Seismic Zone (WQZ) and the Charlevoix-Kamouraska Seismic Zone (CKSZ). With five major earthquakes that occurred during historical times and hundreds of minor earthquakes, the CKSZ is the most active seismic zone in eastern Canada. Here we present new high-resolution multibeam bathymetric, subbottom profiler and sediment core data collected in Lake Temiscouata, southeastern Quebec, the largest lake located within the influence of the CKSZ. The occurrence of mass-movements in the highly cohesive glaciolacustrine deposits of the lake produced a peculiar lacustrine landscape consisting of steep slide scars and residual mounds and very narrow residual crests. Our data indicate that postglacial times were marked by recurrent seismically induced mass-movement events that cannot be individually identified in the sedimentary record due to the highly disturbed stratigraphy of the lake and to the absence of significant postglacial background sediments between events. The most recent recorded mass-movement is a distinct debris flow sediment layer on the lake floor that was deposited at similar to 1300 cal BP, very shortly after a distinct large-scale mass-movement event observed across the entire lake basin. The presence of silt layers in gyttja overlying these disturbed units suggests that the region was affected by other seismic events following this event, although no MMDs could be directly related to these layers.

• 出版日期2017-2-1