Scaling behaviour of clay-rich submarine debris flows

We perform a statistical study of submarine debris flows based on recent data from the Storegga area off the western coast of Norway. Due to the high quality of the data and the uniformity of materials, the data from the Storegga database are far less dispersed than world-wide compilations available so far, allowing for a fit with good statistical significance. We find that both the run-out and the ratio between fall height and run-out are best described as a power-law function of the volume. For small to moderate volumes, visco-plastic models are able to reproduce the power law, in contrast to granular-frictional models. However, either progressive mixing of the shear layer with ambient water or hydro-planing must be invoked in order to explain the extreme run-out distances of larger debris flows.