Analysis Of Multibeam Seafloor Imagery Of The Laurentian Fan And The 1929 Grand Banks Landslide Area.

The 1929 Grand Banks earthquake, landslide and tsunami were pivotal in geologic history as they led to the first unequivocal recognition of a landslide-triggered tsunami and turbidity current. The event is well constrained in terms of trigger, timing, sequence of events and impact. The landslide site was surveyed in September of 2006 with a 12 kHz multibeam echosounder. Regionally, these bathymetric data show canyons, valleys and gullies, somewhat typical of the continental slope in the region. No major headscarp related to the event is recognized (cf. the Storegga Slide). Most significant are a series of shallow gullies with small headwalls about mid-slope. Upslope from these is a series of shallow escarpments that probably represent upslope retrogression of the failure. The landslide appears to have been relatively shallow (top 5-100 m) and laterally extensive. There is no evidence of a single massive submarine landslide with major headscarp and debris lobe. [ABSTRACT FROM AUTHOR]