Late stage slope failure in the wake of the 1929 Grand Banks earthquake

Abstract

Small volume (<15 km3) debris flows which were triggered by the 1929 earthquake postdate the period of high velocity turbidity current flow resulting from that earthquake. They thus could not have contributed sediment to the 1929 cable-breaking turbidity currents. Both the proposed “Grand Banks Slump” and another large scale debris flow also attributed to the 1929 event, are shown to be autochthonous. In light of the limited volume and late-stage timing of mass wasting on the upper Laurentian Fan in 1929, an additional mechanism must have existed which supplied further sediment to the turbidity current in 1929.