Submarine Mass Movements and Their Consequences

Abstract

Mass-transport deposits (MTDs) are widely recognized from many continental margins and are an important component of slope systems. Although MTDs have been studied since the early 1920s, much of the research has been conducted on ancient features partially preserved at outcrop. The incompleteness of outcrop examples has been a persistent obstacle to a fuller, process based analysis of their causes, mechanisms, and results. In the last few decades, increasing use has been made of geophysical techniques such as 2D reflection seismology, sonar, and multibeam bathymetry to study modern MTDs. Many valuable insights have accrued from this approach, but it is, in essence, a two-dimensional analytical framework, and suffers from many of the same limitations as the field-based approach. Recent advent of 3D seismic technology offers a novel method for investigations of both modern and subsurface MTDs that promises to add significantly to the understanding of slope failure processes. Modern, high-resolution 3D seismic surveys are now acquired on many continental margins for hydrocarbon exploration purposes, and often in areas that are or have been affected by slope failure. This means that the remarkable spatial resolving power of the 3D seismic method can be used to define the full areal extent and morphology of MTDs with a precision that cannot be achieved with any other combination of methods. This paper illustrates the potential for 3D seismic interpretation of MTDs by describing a suite of complex examples from different continental margins worldwide. The application of seismic-based analyses for seafloor and near-surface geohazard evaluation associated with submarine slope failure is also discussed.