Knowledge Bank

The 7.2 magnitude earthquake off the coast of Grand Banks Newfoundland in 1929 caused a massive underwater landslide and deadly tsunami, one of the largest recorded in Canadian history. The landslide resulted from the failing of a submarine slump which was jarred loose by the earthquake, which displaced a massive volume of sediment and turbidity currents which in turn created a tsunami. Using past research and collected data such as seismic cross sections, as well as reasonable assumptions for data which must be inferred, this study aims to find stress values at different depths that would cause failure of a nearby slump while factoring in pore pressure. This method uses Mohr-Coulomb circles to calculate required pore pressure increases from hydrostatic pressure to cause failure in a modern day slump near the 1929 epicenter. These findings determine that the slump studied is relatively stable when the pore pressure is assumed to be hydrostatic and for most of the six scenarios analyzed. Found pore pressure increases needed were ~3.5 MPa to ~10 MPa for the weakest scenarios for the slump, and increases of ~8 MPa to ~22 MPa for the stronger scenarios to cause their Mohr-Circles to contact the failure envelope. These findings and methods can be used for slumps in the surrounding area and for other locations around the world near passive margins with submarine slumps.