Submarine Geohazards and Sedimentology
The Submarine Geohazards and Sedimentology research group studies underwater landslides and flows of sediment, where the scales involved can be spectacular. The largest landslides on our planet occur underwater, some of them being bigger than Scotland. Perhaps more remarkably, these landslides occur on seafloor with a gradient of just one or two degrees. Slopes on land with such low gradients are almost always stable.
We seek to understand the risk posed by tsunamis generated by underwater landslides, how they are triggered, and why such large-scale failure can occur on such low gradients. Our work has involved studying large landslides generated by volcanic flank collapse in the Canary Islands, and Cape Verde Islands. More recently, we have collected the most detailed geophysical dataset (including the first three-dimensional seismic survey) yet available for submarine landslides, located offshore from an active volcano on Montserrat in the Lesser Antilles.
We are a centre of excellence for studying flows of sediment called turbidity currents that travel (sometimes very quickly at up to 20 m/s) along the seafloor. These flows are one of the most important processes for moving sediment across our planet, and just one turbidity current can transport more sediment than the annual flux from all of the world’s rivers.
Turbidity currents sometimes travel for several thousand kilometres across gradients of less than 0.1°, making them the longest run-out sediment density flows yet recognised on Earth. The flows can be very destructive, breaking networks of cables on the seafloor. This cable network carries over 95 % of international telecommunications; only 5 % is routed via satellites. The cables underpin the internet, global financial markets and many other aspects of our daily lives.
For instance, turbidity currents broke cables offshore from SE Taiwan in 2006, 2009, and 2010, causing severe disruption to South East Asia’s regional and global telecommunications in 2006.
Turbidity currents have produced the largest sediment accumulations on Earth called submarine fans. Ancient submarine fan deposits now hold some of our largest subsurface oil and gas reserves, whereas turbidity currents and submarine landslides are a hazard to seafloor structures used to recover those oil and gas reserves.
Our research integrates mapping and sampling of the modern sea floor, analysis of ancient rock sequences, physical laboratory experiments, and numerical modelling. We benefit from close collaborations with colleagues in the School of Ocean and Earth Sciences and the School of Civil Engineering and the Environment in the University of Southampton.