Frontally Confined Against Frontally Emergent Submarine Landslides: A 3-D Seismic Characterization

Jose Frey-Martinez¹, Joe Cartwright², and David James^2
1 BG-Group, Reading, United Kingdom
² Cardiff University, Cardiff, United Kingdom

Three-dimensional (3D) seismic data from the continental margin offshore Israel (Eastern Mediterranean) have been used to analyse the compressional structures within the toe regions of two major buried submarine landslides: the Israel Slump Complex (ISC) and the T20 Slump. Both landslides are developed within a Plio-Pleistocene slope succession predominately composed of siltstones and claystones. The high spatial resolution provided by the seismic data has allowed a detailed analysis of the geometries and deformational structures within the toe regions of the two slump masses, and this has been used to develop a mechanical model for their development. Importantly, it has been recognised that submarine landslides may be divided into two main types according to their form of frontal emplacement: frontally confined and frontally emergent. In the former, the landslide undergoes a restricted downslope translation and does not overrun the undeformed downslope strata. In the latter, much larger downslope translation occurs because the landslide is able to ramp up from its original basal shear surface and translate in an unconfined manner over the seafloor. The division of submarine landslides into these two classes is of critical importance as their respective mechanisms of formation, downslope propagation and emplacement are fundamentally different, and hence need to be taken into consideration when analysing their kinematics.