Developing a Global Listening Network for Turbidity Currents and Seafloor Processes

Lead Research Organisation: Durham University
Department Name: Earth Sciences


Our overall aim is to make fundamental step-changes in understanding of seafloor processes and hazards by developing and demonstrating novel sensor systems, which can form widespread and long-term listening networks. These low-cost and energy-efficient sensors comprise hydrophones (acoustic noise in water column) and geophones (ground shaking). Data will be returned via pop-up floats and satellite links, as has been pioneered by the highly successful Argo Project for water-column profile.

This type of low-cost network could have unusually widespread applications for warning against threats to valuable seabed infrastructure, monitoring leaks from CCS facilities or gas pipelines, or for tsunami warning systems. Here we aim to answer fundamental questions about how submarine mass-flows (turbidity currents and landslides) are triggered, and then behave. These hazardous and often powerful (2-20 m/s) submarine events form the largest sediment accumulations, deepest canyons, and longest channel systems on our planet. Turbidity currents can runout for hundreds to thousands of kilometres, to break seabed cable networks that carry >95% of global data traffic, including the internet and financial markets, or strategic oil and gas pipelines. These flows play a globally important role in organic carbon and nutrient transfer to the deep ocean, and geochemical cycles; whilst their deposits host valuable oil and gas reserves worldwide.

Submarine mass flows are notoriously difficult to measure in action, and there are very few measurements compared to their subaerial cousins. This means there are fundamental gaps in basic understanding about how submarine mass flows are triggered, their frequency and runout, and how they behave. Recent monitoring has made advances using power-hungry (active source) sensors, such as acoustic Doppler current profilers (ADCPs). But active-source sensors have major disadvantages, and cannot be deployed globally. They can only measure for short periods, are located on moorings anchored inside these powerful flows (which often carry the expensive mooring and sensors away), and they need multiple periods of expensive research vessels to be both deployed and recovered. We will therefore design, build and test passive sensors that can be deployed over widespread areas at far lower cost. These novel sensors will record mass-flow timing and triggers; and changes in front speed (from transit times), and flow power (via strength of acoustic or vibration signal).

We will first determine how submarine mass flows are best recorded by hydrophones and geophones, and how that record varies with flow speed and type, or distance to sensor. Our preliminary work at three sites already shows that hydrophone and geophones do record mass-flows. Here we will determine the best way to capture that mass-flow signal, and to distinguish it from other processes.

This work will form the basis for designing a new generation of low-cost (< £5k) smart sensors that return data without expensive surface vessels; via pop-up floats and satellite links. Advances in technology make this project timely, as they allow on-board data processing by smart hydrophones or geophones to reduce data volumes, which can be triggered to record for short periods at much higher frequency.

We will field-test the new smart sensors, and thus demonstrate how they can answer major science questions. We seek to understand what triggers submarine flows, and how this initial trigger mechanism affects flow behaviour. In particular, how are submarine flows linked to hazardous river floods, storms or earthquakes, and hence how do they record those hazards? Do submarine flows in diverse settings show consistent modes of behaviour, and if not, what causes those differences? To do this, we will deploy these new sensors along the Congo Canyon (dilute river, passive margin, no cyclones) offshore Taiwan.

Planned Impact

Beneficiaries of this work are unusually wide-ranging, both from new insights into submarine mass flows, and the development of low-cost sensor networks with widespread applications.

Seafloor telecommunication cables: Seabed cable networks have strategic importance because they carry >95% of global data traffic, including internet and financial markets. It is important to understand spatial changes in turbidity current frequency and power to optimise the location of future cables. It is also important to understand which types and speeds of turbidity current break cables, and which do not. This project will study the Gaoping Canyon, where flows have previously broken many seafloor cables repreatedly, which is a major pinch point in the global cable routes. We will work with Carter of the ICPC, an umbrella organisation for submarine cable owners and operators, to disseminate results.

Marine cyber-security: There is increasing concern over human tampering with seabed cables using Remotely Operated Vehicles (ROVs), as set out in a 2017 report by UK Member of Parliament, Rishi Sunak. A key recommendation of that report is to develop remote sensing systems that can warn against the approach of a ROVs. We will test whether low-cost hydrophones, which transmit a warning via a pop-up data pod, can successfully detect the approach of an ROV. Our results will be communicated to the Department for Digital, Media, Culture and Sport who have formal responsibility for seafloor cable security; and to the ICPC via Carter.

Hazards to seabed pipelines and other infrastructure: Turbidity current and landslides pose a substantial threat to oil and gas pipelines, and other seabed infrastructure. First, our project will help to understand how frequency, duration and power of flows varies with distance along canyon, and hence where pipelines are best routed. Second, we will test whether low-cost hydrophones and geophones can provide a reliable early warning for hazardous submarine mass flows. We will disseminate results via Clare's Knowledge Exchange Fellowship, and via presentations at the Offshore Technology Conference.

Leaks from pipelines: Hydrophones have successfully located and quantify gas leaks from pipelines in the North Sea (Wiggin et al., 2015). This project will show how low-cost hydrophones can transmit data without an expensive surface vessel, which may warn against leaks.

Leaks from carbon capture and storage (CCS) facilities: Hydrophones can remotely detect and quantify gas leakage over large areas, and thus currently play an important role in monitoring CCS facilities. This project will contribute to such efforts in producing smart hydrophones, which can be triggered to record at higher frequencies, and which return data without the need for a surface vessel.

Oil and Gas Reservoir Characterisation: Deposits of turbidity currents host valuable oil and gas reservoirs in locations worldwide. This project will produce two of the most complete datasets from across two large submarine systems (Congo and Gaoping), where deposits can be compared to direct flow measurements. Laboratory-scale experiments and numerical models underpin many reservoir models, and understanding of these flows more generally. This project will produce a timely and robust test of such models, as predicted flow evolution can be compared to the observed changes in flows.

Marine Biologists: An important use of hydrophones is determine presence and behaviour of marine mammals. Our project helps to develop low-cost hydrophones that return their data without a surface vessel, which have widespread application for marine biologists. Turbidity currents supply important nutrients to submarine canyon ecosystems, which are hot spots of biological diversity. Our work in Gaoping and Congo Canyon will thus help to understand benthic ecosystems function in the deep sea.


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Heerema C (2020) What determines the downstream evolution of turbidity currents? in Earth and Planetary Science Letters

Description We have successfully deployed the hydrophones and geophones, and we will recover the instruments in 2020.
Exploitation Route The finding help understand the hazards these submarine flows pose to seabed cable networks that underpin the global internet.
Sectors Digital/Communication/Information Technologies (including Software)

Description Angola Cables 
Organisation Angola Cables
Country Angola 
Sector Private 
PI Contribution We have signed a MOU with Angola Cables, regarding hazards to offshore telecommunications cables from there flows. These cables supply the internet to West Africa, and can be broken by submarine flows.
Collaborator Contribution We have signed a MOU with Angola Cables, regarding hazards to offshore telecommunications cables from there flows. These cables supply the internet to West Africa, and can be broken by submarine flows.
Impact Advice to the submarine telecomms companies with cables off West Africa.
Start Year 2019
Description Canadian Geological Survey - shared ship time 
Organisation Natural Resources Canada
Department Geological Survey of Canada
Country Canada 
Sector Public 
PI Contribution We have provided equipment, people and expertise in offshore mapping of marine geohazards, including landslides.
Collaborator Contribution The Canadian geological Survey based in Victoria, Vancouver Island have made over 35 days of ship time available on the research vessel (the Vector)
Impact We have contributed to offshore risk assessment in places such as Kitimak Arm, where there are LNG terminal planned.
Start Year 2016
Description Monterey Bay Aquarium Research Institute 
Organisation Monterey Bay Aquarium Research Institute
Country United States 
Sector Academic/University 
PI Contribution Monterey Bay Aquarium Research Institute provided and managed 34 separate cruises, using their state of the art RPOVs and AUVs. This contribution was several times that of the NERC Grant. It resulted in by far the most ambitious monitoring of a submarine canyon anywhere in the world.
Collaborator Contribution Monterey Bay Aquarium Research Institute provided and managed 34 separate cruises, using their state of the art RPOVs and AUVs.
Impact Monterey Bay Aquarium Research Institute provided and managed 34 separate cruises, using their state of the art RPOVs and AUVs. It involved marine geology and geohazards, and development of cutting edge offshore technology.
Start Year 2016