"The 1929 Grand Banks event: Geohazards and deposits. Cruise MSM47 (on board Maria S. Merian) " by Jaume Llopart, ICM, will be held at room Sala d'Actes of Institut de Ciencies del Mar (ICM - www.icm.csic.es).
On November 18, 1929, a M7.2 earthquake occurred beneath the Laurentian Channel off thecoast of Newfoundland. Nearly simultaneously, 12 undersea trans-Atlantic communicationcables were severed and within two hours, a devastating tsunami struck the south coast ofNewfoundland, claiming 28 lives. Only in 1952, it was understood that a slump-generatedturbidity current caused the sequential severance of the cables and likely generated thetsunami. The 1929 Grand Banks events were pivotal, as they led to the first unequivocalrecognition of a turbidity current and landslide-triggered tsunami. The landslide site wasvisited numerous times as underwater survey technologies evolved. No major headscarprelated to the event is recognized. The landslide appears to have affected shallow sediments(top 5-100 m) and was laterally extensive. The objective of this mission is to test thehypothesis that a distributed, laterally extensive, shallow submarine mass failure eventcaused the tsunami. This hypothesis is contrary to accepted models of tsunamis generationby landslides, in which a solid mass of material needs to be almost instantly displaced,creating large headscarps. To conduct this study, high-resolution multibeam bathymetricdata, subbottom profile data and seismic reflection data need to be acquired over thelandslide region. Sedimentological and geotechnical data will be collected to characterize thesedimentary succession. If the hypothesis proves to be true, then the results of this studyhave great significance, as many continental margins exhibit similar geomorphological traits,with many small escarpments presumably related to submarine landslides.