Characterisation of Submarine Landslides on the Eastern Slopes of the Eivissa Channel, Western Mediterranean Sea
Submarine landslides pose a risk to offshore infrastructure and can generate devastating tsunamis. There exist a range of hypotheses about pre-conditioning factors and trigger mechanisms, yet the understanding of landslide development and emplacement processes has been limited to a few case studies. On the one hand, this is partly because the study of sub-seafloor structures is limited to sediment echosounder profiles and 2D and rarely 3D reflection seismic data. However, because these data are expensive to acquire, data coverage is sparse and often of low resolution. On the other hand, historical records of landslide- generated tsunamis are rare, and can often not be differentiated from tsunamis generated exclusively by earthquakes. In addition, the study of active slope failures is mainly based on the 2D and 3D reflection seismic analysis of their remnants – the mass transport deposits (MTDs) – meaning that slope failure development and emplacement processes can only be interpreted from these remains. Interpretation of reflection seismic data is a highly ambiguous task and depends on the data which includes resolution and penetration depth and the experience of the interpreter. Monitoring of active failure processes has only been successful to a limited extent, for instance by measurements of landslide velocities deduced from telecommunication cable breaks. Because of the large size of submarine landslides, it is becoming more and more evident that they can deform seafloor sediments to significant depth. Furthermore, stations and platforms installed directly on the seafloor can be damaged or buried by landslide material or even be incorporated into the slope failure.
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