ESSAFE PROJECT
Tsunami early warning system using available seafloor fiber cables
This project has received funding from the European Union’s Horizon Europe research and innovation programme under grant agreement Nº 10109899
Introduction
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. In the worst Tsunamies between 1998 and 2017, more than 250.000 people were killed and vast material damage was caused. Tsunamis are unpredictable in nature and their impact can only be mitigated using dedicated tsunami warning systems relying on networks of offshore sensors. Unfortunately, current tsunami warning systems (typically based on special buoys) are unreliable as they suffer frequent breakdowns. In addition, the cost of the most reliable currently-available tsunami warning systems is extremely high and essentially only affordable to rich countries like the US or Japan. As such, the vast majority of all the endangered population in the world is not yet protected by an efficient tsunami warning system. With the upcoming climatic crisis, and the increasing likelihood of extreme weather events, the risk of tsunamis or other catastrophic sea natural phenomena will only rise in the following years. This project will use the conventional submarine optical fibre communication cables lying in the seabed to monitor earthquakes and track sea level changes. Our approach will use a technology known as Distributed Acoustic Sensing (DAS) that transforms an optical fibre communications cable into a very powerful seismic sensing array with thousands of measurement points along the cable.
Luckily, the vast majority of coastal areas in the world (including those in development countries) have already-available 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 the SAFE 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.
Technologies Used
Distributed Acoustic Sensing (DAS) has been recently demonstrated as a convenient alternative to OBS in underwater scenarios. DAS systems allow for the fully distributed monitoring of seismic vibrations along a conventional, already-available submarine telecom optical fiber cable. In DAS, the optical fiber cable acts as a continuous array of geophones/hydrophones, which are interrogated with a single opto-electronic unit located in one end of the cable. The advantage of DAS is that it can make use of the existing fiber network infrastructure, with no modification, which implies a huge cost reduction if cables are available in the area. DAS technologies based on deployed optical fiber cables have several advantages over existing TWS: they are much simpler to deploy (just connecting an interrogator in the cable end); they are much simpler to maintain (the electrically powered interrogator is onshore); they provide an array of thousands of synchronized strainmeters underwater, instead of a single measurement point; and they are cost effective solutions. DAS systems may be able to record both tsunamigenic earthquakes and tsunami waves. As such, these systems will significantly augment present seismic and tsunami detection networks offshore and provide more rapid information for TWS. But no DAS-based solution for TWS has been developed yet in the world.
The proposed proprietary technology (HDAS of High-Fidelity DAS) used in the project uses a novel linearly chirped pulses technique that presents a linear response independent of amplitude and polarization fluctuations (patent PCT/ES2016/070851). To further reduce the noise HDAS uses a thermally and mechanically-isolated reference fiber to correct the vast majority of laser phase noise issues, leading to very low values of strain noise. The technique also completely avoids the phase determination methodology used in conventional equipment (the measurement is transformed into a time-delay estimation process). In this way, the reference updates of the system can be made very infrequent (in the order of minutes or hours), leading to a very low 1/f noise at low frequencies. Due to these advantages, the HDAS interrogator provides extremely linear and robust shot-to-shot measurements of seismic vibrations across the fiber with consistent sensitivity (unlike traditional DAS) and uniformly low noise across the whole fiber used for sensing. This allows to determine long-period natural processes (e.g., tsunamis, tides, infragravity waves, etc.) with extremely good accuracy and a spatial and temporal coverage never seen before. Given all these advantages, seismologists and oceanographers are already starting to adopt this system based on our patented chirped-pulse technology. This technology provides the ideal platform for developing the first commercial Tsunami Warning System based on available fiber-optic cables.
The sensor would be useless without a reliable interpretation software capable of launching alarms whenever tsunamigenic events are detected. The development of this software will be key in the commercial success of the device. For this purpose, the consortium in this project incorporates a seismology group with expertise in earthquake and tsunami warning (GeoAzur). The consortium also incorporates IPMA, the Portuguese authority for tsunami early warning and an ICG-NEAMTWS-accredited international tsunami service provider for the NE Atlantic. These groups will collaborate in the development and validation of the AI layer that will be licensed to APL after an in-depth evaluation in the field.
Consortium
GeoAzur Laboratory
Located near Nice, France, is an Earth sciences research center with a vast experience in marine geophysics and seafloor instrumentation, as well as earthquake and tsunami science (observational, theoretical and computational). The laboratory is part of Université Côte d’Azur (UCA), one of the few French universities to hold the prestigious Initiative of Excellence status. The Geoazur DAS team is composed of 3 permanent researchers supervising graduate students and postdoctoral researchers. The team is pioneer in the use of DAS on seafloor telecom cables for Earth sciences and has developed methods to analyze DAS data for applications in seismology, oceanography, traffic monitoring, including deep learning methods for data denoising and signal characterization. The team has tight collaborations with 3iA Côte d’Azur, one of the four Interdisciplinary Institutes for Artificial Intelligence created in France in 2019. The senior member of the team, Jean-Paul Ampuero, is an expert in earthquake seismology and holds an Excellence Chair at UCA. He has published more than 150 articles, including 5 in Science and 4 in Nature Geoscience. He was elected Fellow of the American Geophysical Union in 2020 for his “exceptional contributions to Earth sciences through breakthrough, discovery and innovation”. He has trained 10 PhDs and 13 postdocs, including current faculty at Oxford, UCLA and Scripps IO. He participated in ShakeAlert, the project that developed the California earthquake warning system, while he was Professor at Caltech (2008-2018) and is currently developing operational AI algorithms for the earthquake early warning system of Peru. The junior member of the team, Diane Rivet, is leading DAS experiments on telecom fiber optic cables offshore Chile to advance earthquake research and early warning.
Portuguese Institute for the Ocean and Atmosphere
State Laboratory in Portugal whose mission is to promote and coordinate scientific research, technological development, innovation, and the provision of services in the domains of the sea and the atmosphere. It is the national authority in the fields of meteorology, climate, seismology, geomagnetism and in the assessment and advice on the management of fisheries resources and their ecosystems. IPMA is also responsible for the operation and maintenance of national networks of meteorological, geophysical, oceanographic, living resources and fisheries observation, and for the operation of the corresponding warning systems, in conjunction with the national civil protection authorities. It operates one of the tsunami warning centers as part of the Tsunami Early Warning and Mitigation System in the NE Atlantic, the Mediterranean and connected seas (ICG/NEAMTWS). IPMA actively participates in the major Global initiatives, European and National projects for the development of early warning services for tsunamis and earthquakes, hazard mitigation and earth observation, cooperating in the integration of observation networks for seismic activity and sea level. In collaboration with Instituto de Telecomunicações (IT) and Instituto Dom Luiz (IDL), IPMA has recently launched the initiative of the LEA project – Listening to the Earth under the Atlantic- with the aims to: i) promote research, development, and training on the observation of geophysical and oceanographic phenomena using submarine cables; ii) inform and advise national and international authorities on the opportunities and implications for science, technology, society, and innovation offered by the use of submarine cables; iii) establish partnerships with national and international entities aiming to the promotion of detection of geophysical and oceanographic phenomena using submarine cables.
University of Alcala
The Photonics Engineering group at the University of Alcala (UAH) is one of the top-rated research groups at the UAH, given its high scientific production and its strong technology transfer activity. Over the last few years, the scientific activity of the group has been very intense, particularly in the development of distributed optical fiber sensing solutions for monitoring temperature or strain along tens of kilometers of large infrastructures such as railways, oil and gas pipelines and electricity lines, with the best resolution and sensitivity achievable in these long range scenarios. For more than 12 years, the group has been developing not only high-visibility scientific work on this subject (8 Best Paper Awards in different conferences), but also several patents that are at the core of several products in the distributed sensing market. One of the key results of that project was the invention of chirped-pulse DAS (PCT/ES2016/070851), the technology behind high-fidelity DAS. Since then, this technique has been at the core of many investigations of the group as it offers disruptive properties that have not only spurred the interest of the scientific community, but also from commercial companies.
News
Visit to the Casablanca platform
Last April, Repsol invited us to visit the Casablanca
Presentation of “Ready for the Tsunami?”
Our leaders Francisco M. López Torres and Jorge López
International Union of Railways (UIC) Workshop
This February we had the opportunity to attend the UIC
