Grand Banks Earthquake of 1929 and the ‘Instantaneous’ Cable Failures

Abstract

THE Grand Banks earthquake and the associated disturbances have received attention from all students of marine geology, particularly since the publication of the classical interpretation of the submarine cable failures by Heezen and Ewing¹. In their recent publication, “Grand Banks Slump”, Heezen and Drake² have attributed the virtually instantaneous cable failures around the epicentre of the earthquake to an initial slump, triggered by the shock. In their original interpretation, Heezen and Ewing attributed the later, systematic cable failures for a period of 13 h 17 min to the action of the turbidity current dislodged by the initial shock. The cause behind the almost instantaneous failure of six cables lying 150–1,800 fathoms on the continental slope, however, remained unexplained at that time. The original authors attributed these, rather vaguely, to “initial ground motion, or almost instantaneous slumps and slides”.