SAFE: Tsunami early warning System using Availableseafloor Fiber cablEs

Project Information

SAFE

Grant agreement ID: 101098992

DOI

10.3030/101098992

Project closed

EC signature date 26 October 2022

Start date 1 December 2022

End date 28 February 2026

Funded under

• The European Innovation Council (EIC)

Total cost

€ 1 162 210,25

EU contribution

€ 1 162 209,25

Coordinated by

UNIVERSIDAD DE ALCALA
Spain

Periodic Reporting for period 2 - SAFE (SAFE: Tsunami early warning System using Availableseafloor Fiber cablEs)

Reporting period: 2023-12-01 to 2026-02-28

Summary of the context and overall objectives of the project

According to the World Health Organization, more than 700 million people live in low-lying coastal areas and Small Island Developing States exposed to extreme sea-level events including tsunamis. The cost of the most reliable currently-available tsunami warning systems (based on offshore sensors) is extremely high and essentially only affordable to rich countries like the US or Japan. As such, the vast majority of all this endangered population is not yet protected by this type of tsunami warning system. Luckily, the vast majority of these coastal areas have alreadyavailable fibre-optic cables installed (for communication purposes) which could additionally serve as a key component for tsunami early warning, at a marginal extra cost. The objective of this project is to fulfill the need of protecting these communities, which often have limited resources, by providing a tsunami early warning solution based on the already-available fibre optic infrastructure. The solution provided in this project will be simple to deploy and maintain (just connecting an interrogator in the dry end of the fiber-optic cable), low cost (it will be several orders of magnitude cheaper than current systems), reliable (tsunami alerts will be confirmed by the same device using indirect measurements of sea level) and timely (the response time is expected to be faster than current systems). The main market of this solution will be official meteorological and environmental institutions of different countries responsible for issuing early warnings.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

The core objective of the project is the development of a tsunami early warning product (TWS) comprising a long range distributed acoustic sensor (DAS) and the artificial intelligence (AI) layer capable of launching reliable alarms upon the detection of potential tsunamigenic activity and tsunami waves. Along the project duration, the main achievements towards this goal have been: (1) the development of a new DAS architecture with long-range capability and an extremely good performance at low frequencies; (2) the development of several AI tools to detect earthquakes and provide an early estimate of water column changes for tsunami wave confirmation and early warning; (3) the pre-validation of the full solution in a cable in the Alboran Sea and (4) the development of a full business plan and business model for the future commercial exploitation of this solution.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The project has contributed to go beyond the scientific state of the art as evidenced in the following results:
- The DAS technology developed in the project has a record performance in terms of instrument self noise at low frequency below 1 Hz.
- The technology has been essential to achieve the first high-resolution spatially-resolved visualization of tidal-driven internal waves in the ocean. These results prove that changes in the water column can be monitored with DAS, and particularly with our low-noise high-fidelity DAS system.
- We fhave done the first complete quantification of the potential contribution of all conceivable mechanisms by which a tsunamis may generate longitudinal strain on a seafloor cable, including seafloor compliance and Poisson’s effect of the cable induced by hydrostatic pressure, seafloor shear and temperature transients induced by deep fluid flow. We found that the seafloor compliance and Poisson’s effect are the dominant mechanisms over the most relevant conditions. We also verified that our theoretical estimate of the seafloor compliance signal agrees with results of a fully-coupled 3D simulation of earthquake, tsunami and seismo-acoustic waves. We also quantified potential sources of environmental noise, in particular low-frequency background temperature fluctuations. We finally compared the signal amplitudes to the expected noise floor of low-frequency DAS interrogators. Overall, the analysis shows that tsunami can be detected with good signal-to-noise ratio by low-frequency DAS instruments, within a few minutes of the earthquake onset, on seafloor cables located above or near the source area.
- We have developed some of the first methods to achieve earthquake localization by backprojection of DAS data, with accuracies comparable to those obtained using in-land stations. This will allow issuing early warnings sooner than current systems.
- With the available datasets and the above model of strain induced by tsunami waves on the cable, we have developed an algorithm that allows tracking changes in water column with errors below 20 cm using simple fibre optic cables already available in the sea bottom.

The future uptake of our solution for tsunami warning will depend on a number of factors, the key one being the acceptance among cable owners. Therefore, the project has also invested a significant effort in developing some of the first AI toold that allow vessel detection and distance estimation for third party intrusion in cables.