Geohazards
Submarine geohazards can pose a significant risk to life and property, as seen perhaps most clearly in the earthquake-generated 2004 Indian Ocean and 2011 Japan tsunamis. Submarine geohazards are also important for global economies. Over 95% of global internet traffic travels through a network of sea floor cables, which can be broken by underwater landslides and associated powerful flows of sediment that can travel at speeds of tens of metres per second.
Submarine volcanos
Marine sediment can provide a more complete record of volcanic eruptions than is preserved on land, such as the record of past eruptions from layers of ash. The research group has also played a leading role over many years in showing how volcanic islands can undergo large scale collapse, producing some of the largest landslides on Earth.
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Submarine earthquakes
Tsunamis generated by earthquakes can be very damaging, as shown by events in Japan and the Indian Ocean. It has been proposed that layers of sediment formed by underwater sediment flows (turbidity currents) can provide a record of earthquakes. This record is potentially very valuable because it extends back further in time than almost all records on land. Our ongoing work is showing that some earthquakes do not produce these underwater flows of sediment, and this approach therefore needs caution.
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Tsunami
We have much still to learn about the risk posed by tsunamis, including the risk to the UK. For instance, we are collaborating with tsunami modellers to investigate the risk from underwater landslides in the Arctic Oceans, especially as those oceans warm and potentially releasing gas from the sea floor sediment.
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Submarine flows
Submarine flows of sediment (called turbidity currents) are one of the main flow processes for moving sediment across our planet. Just one of these flows can transport ten times the annual sediment flux from all of the World’s rivers combined, and spread this sediment across hundreds of kilometres of sea floor. These flows are an important hazard to sea floor cable networks that carry over 95% of voice and data traffic, which underpins the internet and many financial markets.
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Submarine landslides
Submarine landslides can be far larger in volume and extent that landslides on land. The Storeggga landslides offshore Norway is bigger than Scotland. Perhaps the most remarkable aspect of these landslides is that they can occur on slopes of just one or two degrees. Such low gradient slopes are almost always stable on land, and we are still to determine exactly how submarine landslides are triggered on such extremely low gradients.
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