ERC FOCUS — Earthquake monitoring systems
Product description
European collaborative project (2018 – 2025)
The ERC Focus project wants to use underwater communication cables to help monitor earthquakes. The scientific team proposes to add sensors to communication and subsea optical cables to detect and track climate change, elongations and undersea disruptions. Initial offshore test sites are located in Italy and Guadeloupe, with potential expansion to other earthquake-prone regions such as Japan, Chile and the Mediterranean.
- Catania and Portopalo di Capopassero, Sicily (since 2020)
- Saint-François, Capesterre-Belle-Eau and Saint-Louis de Marie Galante (since 2022)
STUDY AREAS
The primary study area focuses on the northernmost portion of the Alfeo Fault offshore Eastern Sicily, near Mount Etna volcano. This region has experienced numerous devastating historical earthquakes (1693, 1783, 1905, 1908), with many source faults still clearly identified. Cable deployment and initial strain measurements began in October 2020. Bag drop operations took place in September 2021, and DAS (Distributing Acoustic Sensing) measurement campaign was conducted in November 2023. The final measurement campaign is scheduled to conclude in 2025.
A new collaboration between the Focus project and the regional council of Guadeloupe began in 2022. Leveraging the submarine cables installed in 2019 that connect the Guadeloupe islands, initial BOTDR studies have commenced on the connection cabinets operated by Orange. Future campaigns, conducted biannually, will monitor cable deformations and investigate their causes, including thermal variations, underwater gravity slides, storms, cyclones, and turbidite flows.
BOTDR
The project will, for the first time, apply a technique commonly used for the structural health monitoring of large-scale engineering structures (bridges, dams, pipelines) — laser reflectometry, specifically Brillouin Optical Time Domain Reflectometry (BOTDR) — to the study of submarine faults. The BOTDR technique, under ideal conditions, can measure very small strains typically 10–500 microstrain) at very large distances (10–200 km) and at a spatial resolution of a few meters.
CABLES ARCHITECTURE
Our prototype seafloor sensor cable measures 6 km in length and 9 mm in diameter. It contains two loosely buffered fibers, meeting telecom standards, and three tightly buffered fibers. Due to the seabed’s irregularity, only half of the cable could be buried in the sediment. BOTDR (Brillouin Optical Time Domain Reflectometry) has detected strain variations at a depth of 2000 meters, and DAS (Distributed Acoustic Sensing) has identified a magnitude 3.5 earthquake. Over four years, we documented strain transfer in both loose and tight fibers through onsite and laboratory experiments, revealing that tightly buffered fibers are more sensitive than loosely buffered ones.
We are currently testing a new hybrid cable that incorporates copper pairs. These copper pairs are designed to amplify signals and provide the capability to transmit more energy if needed.
GALLERY
PARTNERS
- IDIL
- Geo-Ocean
- Ifremer
- INFN
- ERC
