Geophysical characterisation of submarine landslide deposits
Jonathan Ford | OGS Trieste
Submarine landslide deposits have a characteristic “acoustically transparent” or “chaotic” texture in seismic and sub-bottom profiler data. However in outcrop examples we often identify seismic-scale structure: folding and faulting, lithological boundaries and included blocks. Landslide deposits differ from other sediments because they can show strong lateral deformation due to sliding. Slide processes can also alter the lithology and petrophysics properties. This project aims to investigate the main structural and petrophysical controls on the seismic response.
I am using information from outcrops, downhole logs and cores to build realistic high resolution visco-elastic models of submarine landslide deposits. Randomly varying the parameters allows us to model a range of realistic landslide scenarios. Using seismic forward modelling we can compare this known geology to the geophysical response.
Better understanding seismic wave propagation inside submarine landslide deposits will allow better seismic imaging and give a fuller understanding of seismic resolution. This will assist interpreters studying the internal structure of these deposits. In the future we hope to be able to estimate elastic properties of slope sediments (pre- and post-failure) directly from multi-channel seismic data. Using this information we can estimate shear strength and the likelihood of further slope failure. This would allow better estimation of submarine landslide hazard to seafloor infrastructure and to coastal populations from tsunami.