What threat do turbidity currents and submarine landslides pose to strategic submarine telecommunications cable infrastructure?

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It is not widely known that the global economy relies on uninterrupted usage of a network of telecommunication cables on the seafloor. Yet these submarine cables carry ~99% of all inter-continental digital data traffic worldwide, as they have far greater bandwidth than satellites. Over 9 million SWIFT banks transfers alone were made using these cables in 2004, totally $7.4 trillion of transactions per day between 208 countries. Our dependence on these cables is growing, for example there were 15 million SWIFT bank transactions last year. Submarine cables thus have considerable strategic importance to the UK because this data traffic includes the internet, defence information, financial markets and other services that underpin daily lives. This project is timely because submarine cable breaks are a notable omission from the UK National Risk Register. It focusses on the industry challenge of why exactly, how often, and where are seafloor cables broken by natural causes, primarily subsea landslides and sediment flows (turbidity currents). These slides and flows can be very destructive. A flow in 1929 travelled at 19 ms-1 and broke 11 cables in the NE Atlantic, running out for ~800 km to the deep sea. A repeat event would break far more cables today. It is difficult to mitigate against multiple breaks from such flows/slides because data traffic cannot be re-routed along adjacent cables. This contrasts with trawling (or other human activities) that break a single cable. This study is in conjunction with Global Marine and the International Cable Protection Committee. The ICPC is the global umbrella body for the submarine cable sector, and hosts Talling's Royal Society Industry Fellowship. This will be the first study to statistically analyse a global database of cable breaks and causes. It will use novel field and laboratory experiments to show how cables abrade or break.The main project impacts are: (1) We will provide our industry partners (ICPC, individual cable companies) with the first global statistical analysis of the frequency and causes (earthquake, typhoons) of cable breaks. (2) We will map geographic "pinch points" in the global seafloor network that are most at risk from specific hazards; thus helping our partners to design cable routes. These results will help to assess where future climate change is most likely to impact upon cable routes. (3) Laboratory experiments and a novel full-scale field experiment will help our industry partners to understand exactly how cables are broken by submarine flows (and why they sometimes fail to break). Results will be presented at workshops with individual cable companies, and at the ICPC's plenary meeting. Such meetings will provide a global forum for discussion of future strategies for reducing cable breaks. (4) A briefing document will be delivered to the UK Natural Hazards Partnership and Cabinet Office that sets out the basis for whether submarine cable breaks should be included in the UK National Risk Register. This project has wide relevance for multiple geographic and geologic settings and the global subsea communications industry. Other type of expensive and strategically important seafloor infrastructure are also susceptible to impacts by submarine flows/slides, including export pipelines and in-field flowline for oil and gas, and umbilicals that transfer chemicals, power and communications. This project's findings will help to assess the risk posed to these other types of subsea infrastructure by submarine flows/slides. Our project partners include those interested in risks to seafloor pipeline used to carry treated water (Carroll at ScottishWater), and oil and gas networks worldwide (Jobe, Sylvester, Armitage). Submarine flows deposit layers of sand that now form many valuable oil and gas reservoirs. We will also communicate insights from our project into these processes to interested partners (e.g. Jobe at Shell, Sylvester at Chevron, Armitage at ConocoPhilips).