Summary
SMART Cable Initiative
Historically, the deployment of oceanographic sensors with real-time communications has proven to be demanding in terms of budget, deployment and support requirements.
The SMART Cable initiative is exploring a number of ways in which these sensors could be integrated into commercially standard telecommunication cables to create SMART (Science Monitoring And Reliable Telecommunications) cable systems.
If the scientific community can realise the potential for utilising existing industry and instrastructure to deploy ocean bottom sensors, we have the potential to deliver real savings. This will pave the way for increasing ocean bottom sensor density, accelerating research and monitoring strategies for climate change and Earthquake/Tsunami warning.
The SMART Cable initiative is exploring a number of ways in which these sensors could be integrated into commercially standard telecommunication cables to create SMART (Science Monitoring And Reliable Telecommunications) cable systems.
If the scientific community can realise the potential for utilising existing industry and instrastructure to deploy ocean bottom sensors, we have the potential to deliver real savings. This will pave the way for increasing ocean bottom sensor density, accelerating research and monitoring strategies for climate change and Earthquake/Tsunami warning.
ITU-UNESCO/IOC-WMO Joint Task Force
The advocacy for the SMART cable concept is currently led by the ITU-UNESCO/IOC-WMO Joint Task Force (“JTF”), established in 2012 by the United Nations to investigate the potential of using submarine telecommunications cables for ocean and climate monitoring and disaster warning. This Project is hosted by the Ocean Decade programme, Ocean Observing Co-Design: Evolving ocean observing for a sustainable future.
The JTF collaborates with a number of public and private organisations to assess and develop technologies that have the potential to make SMART cables feasible (Howe et al., 2022).
The JTF collaborates with a number of public and private organisations to assess and develop technologies that have the potential to make SMART cables feasible (Howe et al., 2022).
Background
The InSEA Project
In 2020, the Istituto Nazionale di Geofisica e Vulcanologia (“INGV”) awarded Güralp the contract to design, manufacture, test and deploy a 19km SMART cable system in the Western Ionian Sea. The project, known as InSEA, was funded by the Italian Ministry of Research and hopes to realise the first SMART cable wet demonstrator.
The project will investigate the effectiveness of seismometers and environmental monitoring sensors deployed in and around the repeater housings of traditional telecommunications cable (Howe et al., 2022).
The primary objective of the project is to investigate if the system can be deployed
in a commercially standard manner without compromising the scientific or operational value of the data being transmitted by the sensors.
The system will be deployed off the coast of Catania in Sicily and will connect to an existing offshore junction box. The observation area is prone to numerous natural hazards including seismicity caused by the nearby Mount Etna.
The in-situ measurements from the deployed seismic and pressure sensors will be crucial for generating reliable tsunami height forecasts for the region and will also aid with improving tsunami warning times.
This area has been prone to past events including a major earthquake and tsunami
in 1693 that caused ~60,000 casualties in Catania (Tonini et al., 2011).
The project will investigate the effectiveness of seismometers and environmental monitoring sensors deployed in and around the repeater housings of traditional telecommunications cable (Howe et al., 2022).
The primary objective of the project is to investigate if the system can be deployed
in a commercially standard manner without compromising the scientific or operational value of the data being transmitted by the sensors.
The system will be deployed off the coast of Catania in Sicily and will connect to an existing offshore junction box. The observation area is prone to numerous natural hazards including seismicity caused by the nearby Mount Etna.
The in-situ measurements from the deployed seismic and pressure sensors will be crucial for generating reliable tsunami height forecasts for the region and will also aid with improving tsunami warning times.
This area has been prone to past events including a major earthquake and tsunami
in 1693 that caused ~60,000 casualties in Catania (Tonini et al., 2011).
InSEA SMART Cable - System Overview
Figure 3. InSEA SMART cable system design
At one end of the cable there is a Cable Termination Assembly (CTA). The CTA will connect to an existing underwater junction box via a wet-mateable connector and jumper cable. This will be deployed and connected using an ROV. The CTA houses the constant current power supply, fibre optic systems and facilitates connection to the sea cathode. The power system uses a single conductor in the telecoms cable and utilises a sea-return.
The repeaters housing the seismic sensors will be connected by standard telecoms cable.
The final part of the power system is the sea anode which is housed on the final length of cable. The system will be temporarily powered from the anode-end of the cable for testing during deployment.
The InSea system being designed and manufactured by Güralp will total 19km in length and will incorporate three instrumented repeater housings and three external instrumentation pods.
The repeater housings are reclaimed from a decommissioned system that has been modified internally by Güralp to incorporate the necessary instrumentation. The instrumentation in the repeater housings will consist of a Force Balance Accelerometer (“FBA”) and a Broadband Seismometer mounted within the frame, these will collectively be referred to as the “seismic sensors”.
The instrumentation pods will house an Absolute Pressure Gauge (“APG”) and temperature sensor. The pod will be external to the main repeater so that the sensor elements are externally exposed.
The repeater housings are reclaimed from a decommissioned system that has been modified internally by Güralp to incorporate the necessary instrumentation. The instrumentation in the repeater housings will consist of a Force Balance Accelerometer (“FBA”) and a Broadband Seismometer mounted within the frame, these will collectively be referred to as the “seismic sensors”.
The instrumentation pods will house an Absolute Pressure Gauge (“APG”) and temperature sensor. The pod will be external to the main repeater so that the sensor elements are externally exposed.
Figure 4. Repeater frame and instrumentation pod sensors
INSTRUMENTATION POD:
Seabird SBE 39Plus
The SBE 39Plus temperature sensor has an operating range between -5°C and 45°C with an accuracy of ±0.002°C. The temperature sensor will help to facilitate the monitoring of sea floor oceanographic conditions and will feedback into existing oceanographic models.Paroscientific 8000 Series
The Paroscientific 8000 Series APG has a depth rating of 3,000m and a precision of <0.01% full scale range. Selected for it’s proven performance and robustness, the Paroscientific 8000 has been successfully used in other Güralp ocean bottom sensing systems. It has also proven crucial for tsunami warning systems globally.REPEATER HOUSING:
Fortimus
The Fortimus is a modern force balanace accelerometer with integrated digitiser. It has a flat acceleration response between DC-315 Hz. The instruments’ low self-noise, makes the data useful for local and regional seismic monitoring.Combining the Fortimus and Certimus provides an ultra-wide dynamic range
monitoring station.
Certimus
The Certimus is a triaxial broadband seismometer with a flat frequency response between 120 s and 100 Hz. True broadband performance combined with low self-noise makes it well suited for regional seismic monitoring. The Certimus is used globally for applications ranging from volcano monitoring to regional and national networks.System Design
We have undertaken extensive work to integrate our existing Fortimus and Certimus instruments into the repeater housings. For the purpose of the wet demonstration project, the power circuits and optical amplifiers normally found within the repeater have been removed and replaced with a power supply, media converter and the seismic sensors.
The repeater cylinder is sealed by two bulkheads, within which is a penetrator that carries the optical fibres and the conductor from the cable into the housing. A mechanical bend limiter at each end allows the repeater to pass through the handling machines of the cable laying ship.
The seismic sensors, power supply electronics and media converter are preassembled into metal frames that allow for system testing before they are mounted inside the repeaters.
The repeater cylinder is sealed by two bulkheads, within which is a penetrator that carries the optical fibres and the conductor from the cable into the housing. A mechanical bend limiter at each end allows the repeater to pass through the handling machines of the cable laying ship.
The seismic sensors, power supply electronics and media converter are preassembled into metal frames that allow for system testing before they are mounted inside the repeaters.
The frames are designed to ensure sufficient protection of the sensor and electronics as well as maximising coupling of the sensor components to the frame to improve performance of the sensors during the deployment.
The instrument pod, enclosing the APG and temperature sensor, attaches directly to the telecoms cable. The data cables will run back along the outside of the telecoms cable and enter the repeater through waterproof penetrators. The sensors are mounted far enough away from the repeaters to minimise any thermal effects.
The instrument pod, enclosing the APG and temperature sensor, attaches directly to the telecoms cable. The data cables will run back along the outside of the telecoms cable and enter the repeater through waterproof penetrators. The sensors are mounted far enough away from the repeaters to minimise any thermal effects.
System Deployment
Prior to deployment, a multibeam bathymetric survey will be carried out to evaluate and plan the cable path to be followed during the installation.
The system will be installed following standard methods for telecommunication cables deployment using a commercial cable laying vessel designed to deploy and carry out repairs of subsea telecommunication cables.
The cable path will be designed in a way that will keep the installation depth around 2,300 m and will avoid sharp deformation areas or any asset already existing on the seabed.
A dockside test will be undertaken before the various components are joined and loaded onto the vessel for deployment. A work-class ROV will be used to deploy the system.
The system will be installed following standard methods for telecommunication cables deployment using a commercial cable laying vessel designed to deploy and carry out repairs of subsea telecommunication cables.
The cable path will be designed in a way that will keep the installation depth around 2,300 m and will avoid sharp deformation areas or any asset already existing on the seabed.
A dockside test will be undertaken before the various components are joined and loaded onto the vessel for deployment. A work-class ROV will be used to deploy the system.
Figure 5. Repeater frame with enclosures
Future Work
The InSEA project is a crucial step towards wider acceptance and implementation of SMART cable systems globally.
If successful, the project will demonstrate that high performance seismic and ocean observing sensors can be deployed using commercially standard telecommunication cable laying procedures. This should unlock further potential for increasing ocean floor observation stations in a cost-effective manner. We are keen to continue developing this technology and are actively looking for cable manufacturers with whom we can collaborate in order to take this development further.
We continue to innovate and integrate our modular instrumentation into new
deployment systems to enable the scientific community to progress research in otherwise challenging evironments.
If successful, the project will demonstrate that high performance seismic and ocean observing sensors can be deployed using commercially standard telecommunication cable laying procedures. This should unlock further potential for increasing ocean floor observation stations in a cost-effective manner. We are keen to continue developing this technology and are actively looking for cable manufacturers with whom we can collaborate in order to take this development further.
We continue to innovate and integrate our modular instrumentation into new
deployment systems to enable the scientific community to progress research in otherwise challenging evironments.
References
Howe BM, Angove M, Aucan J, Barnes CR,Barros JS, Bayliff N, Becker NC, Carrilho F, Fouch MJ, Fry B, Jamelot A, Janiszewski H, Kong LSL, Lentz S, Luther DS, Marinaro G, Matias LM, Rowe CA, Sakya AE, Salaree A, Thiele T, Tilmann FJ, von Hillebrandt-Andrade C, Wallace L, Weinstein S and Wilcock W (2022) SMART Subsea Cables for
Observing the Earth and Ocean, Mitigating Environmental Hazards, and Supporting the Blue Economy. Front. Earth Sci. 9:775544. doi: 10.3389/feart.2021.775544
De Santis A, Chiappini M, Marinaro G, Guardato S, Conversano F, D’Anna G, Di Mauro D, Cardin V, Carluccio R, Rende SF, Giordano R, Rossi L, Simeone F, Giacomozzi E, Fertitta G, Costanza A, Donnarumma GP, Riccio R, Siena G and Civitarese G (2022) InSEA Project: Initiatives in Supporting the Consolidation and Enhancement of the EMSO Infrastructure and Related Activities. Front. Mar. Sci. 9:846701. doi: 10.3389/fmars.2022.846701
Tonini, R., Armigliato, A., Pagnoni, G., Zaniboni, F., and Tinti, S. (2011). Tsunami Hazard for the City of Catania, Eastern Sicily, Italy, Assessed by Means of Worst-Case Credible Tsunami Scenario Analysis (WCTSA). Nat. Hazards Earth Syst. Sci. 11 ( ), 1217–1232. doi:10.5194/nhess-11-1217-2011
Observing the Earth and Ocean, Mitigating Environmental Hazards, and Supporting the Blue Economy. Front. Earth Sci. 9:775544. doi: 10.3389/feart.2021.775544
De Santis A, Chiappini M, Marinaro G, Guardato S, Conversano F, D’Anna G, Di Mauro D, Cardin V, Carluccio R, Rende SF, Giordano R, Rossi L, Simeone F, Giacomozzi E, Fertitta G, Costanza A, Donnarumma GP, Riccio R, Siena G and Civitarese G (2022) InSEA Project: Initiatives in Supporting the Consolidation and Enhancement of the EMSO Infrastructure and Related Activities. Front. Mar. Sci. 9:846701. doi: 10.3389/fmars.2022.846701
Tonini, R., Armigliato, A., Pagnoni, G., Zaniboni, F., and Tinti, S. (2011). Tsunami Hazard for the City of Catania, Eastern Sicily, Italy, Assessed by Means of Worst-Case Credible Tsunami Scenario Analysis (WCTSA). Nat. Hazards Earth Syst. Sci. 11 ( ), 1217–1232. doi:10.5194/nhess-11-1217-2011