Galileo conference: Fibre Optic Sensing in Geosciences  

Within the framework of the EU funded FOCUS project, we have established BOTDR (Brillouin Optical Time Domain Reflectometry) time series spanning up to 3 years on academic and commercial fiber-optic cables. Offshore Catania a 6-km-long dedicated fiber-optic cable (connected to a 29-km-long electro-optical cable), recorded natural and man-made strain signals of 40 - 250 microstrain at the seafloor (in 1800 - 2000 m water depths). The strongest natural signal (40 microstrain elongation) developed from 19 - 21 Nov. 2020, where the cable crosses a mapped submarine fault in the first of 4 locations. However, a network of 8 seafloor geodetic stations (acoustic beacons mounted on tripods) recorded no baseline changes, thus ruling out a tectonic movement. A simultaneous positive-negative strain doublet (+40 to -20 microstrain) observed 6 km from shore (in 300 m water depth), suggests a downslope current affected the shallow and deep portions of the fiber-optic cable path length. The 6-km long FOCUS cable includes a redundant, triple-loop, consisting of 1 loose and 2 tight optical fibers. (A second double-loop, consisting of 1 tight and 1 loose fiber is being monitored by a second BOTDR interrogator.) The tightly bound fibers typically record a strain signal twice as high as the loose fibers (40 vs 20 microstrain for the natural signal). Weight bag drops created man-made signals along four 120-m-long segments, with amplitudes of 80 - 250 microstrain (in the tight fibers), which gradually decay in the following months / years.

Baseline measurements were repeatedly taken on the 100-km-long Capo Passero (SE Sicily) electro-optical cable in Oct. 2022, March 2023, and Nov. 2023. The main purpose of the monitoring is to test the maximum range attainable with commercially available BOTDR interrogators. While no significant strain development has been measured on the optical path, we report that with an acquisition time of 2+ hours it is possible to extend the measurement range up to 80 km. This represents a benchmark for future BOTDR measurements over long distances.

In June 2022, in collaboration with the “Conseil Regional” of Guadeloupe and Orange, we began long-term monitoring of a network of unrepeated submarine telecom cables that links the islands of the Guadeloupe archipelago. We repeated the measurements of the same fiber segments (30 - 70 km length), in Dec. 2022, June 2023, Nov/ Dec. 2023, and finally May 2024 in order to identify strain or thermal signals along the cable during the 2-year period. We confirm that using the BOTDR technique, we detect significant shifts in the Brillouin frequency (2 - 5 MHz), which could represent substantial strain signals  (40 - 100 micro-strain in amplitude) in several locations along the cable network. These signals, which can be positive (elongation) or negative (shortening) occur typically in areas of steep seafloor slopes (e.g. the shelf break) or in submarine valleys/canyons. Our preliminary interpretation is that stretching and shortening of the cable (representing about 1 cm over a few hundred meters) is occurring, most likely due to sea-bottom currents. 

How to cite: Gutscher, M.-A., Quetel, L., Cappelli, G., Riccobene, G., Aurnia, S., Nativelle, C., Philippon, M., and Lebrun, J.-F.: Observing seafloor processes by distributed Fiber Optic Sensing: examples from academic cables offshore East Sicily (Italy) and a commercial telecom network in the Guadeloupe archipelago (Lesser Antilles)., Galileo conference: Fibre Optic Sensing in Geosciences, Catania, Italy, 16–20 Jun 2024, GC12-FibreOptic-58, https://doi.org/10.5194/egusphere-gc12-fibreoptic-58, 2024.

Active seismic experiments during the Apollo missions characterized the lunar regolith and crust, while passive monitoring suggested a thermal stress origin for the high-frequency lunar seismic noise. Deploying Distributed Acoustic Sensing (DAS) instruments, capable of withstanding the extreme lunar conditions, would allow to examine various lunar environments including permanently shadowed regions, which trap water ice due to their extremely cold temperatures. Benefiting from high spatial and temporal resolutions, DAS surveys would allow analyzing wave propagation, constructing 2D wave velocity sections, and potentially identifying ice-related velocity variations. How the DAS technology positions in terms of self-noise with respect to Apollo and modern sensors? We estimate the strain noise level of geophones to be around 1 pε/sqrt(Hz). For a 5-km long optic fiber with 10 meters gauge length, the typical self-noise of current DAS systems is around 1 pε/sqrt(Hz). This indicates that DAS instruments may achieve a low noise level on par with the best current geophysical technologies, which is crucial for precise and reliable exploration of lunar structure. We will discuss experiments that would be necessary for qualifying such an instrument for space applications.

How to cite: Tauzin, B., Lognonné, P., Kawamura, T., Panning, M., Jousset, P., Lanticq, V., Mercerat, D., Metaxian, J.-P., Hibert, C., De Raucourt, S., Coutant, O., and Almoric, E.: DAS system for the Moon, Galileo conference: Fibre Optic Sensing in Geosciences, Catania, Italy, 16–20 Jun 2024, GC12-FibreOptic-47, https://doi.org/10.5194/egusphere-gc12-fibreoptic-47, 2024.

Optical fiber sensors constitute the biggest revolution in geophysical and environmental sensor technology since digitization.  Although traditional sensors have been refined through decades of incremental progress, optical fiber sensors provide an entirely new lens with which to study fundamental processes. These sensors are particularly advantageous for systems that require high spatial and temporal resolution (i.e., on the order of 1-10m spatial scale and 100 s to 100 kHz sampling rate).  The UW Fiber Lab has deployed these technologies in Antarctica, Greenland, Alaska, New Zealand, and at a dozen sites in Europe and the lower United States.  The main focus of this research has been on studying Earth's cryosphere, submarine, urban, and otherwise difficult-to-instrument environments. This talk will focus specifically on use cases where basic knowledge has been gained regarding the calving front of large, ocean-terminating glaciers in Greenland, paleoclimatic history of the Antarctic ice sheet, monitoring of clean energy systems, and earthquake detection and ground motion hazard characterization.  The presentation will conclude with a forward looking discussion regarding the rapid pace of development of basic optical physics and engineering, and the prospects for future growth at the intersection of optical fiber sensor technology and basic geoscience research.

How to cite: Lipovsky, B., Abadi, S., Denolle, M., Gaete Elgueta, V., Gräff, D., Manos, J.-M., Ni, Y., Shi, Q., Sprinkle, P., Wilcock, W., and Williams, E.: New Earth and Planetary Science Discoveries Enabled by the Optical Fiber Sensing Revolution, Galileo conference: Fibre Optic Sensing in Geosciences, Catania, Italy, 16–20 Jun 2024, GC12-FibreOptic-95, https://doi.org/10.5194/egusphere-gc12-fibreoptic-95, 2024.

I present the results of the Suboptic working group formed during the Suboptic 2023 conference to create a synergy between submarine cable owners and government institutions to improve safety for coastal communities. 

Since discovery of sensing capabilities of operational submarine cables, a perfect storm of smart optical spectroscopic techniques enabled enhancement of cable security and environmental protection. We are looking for synergy between cable owners and government institutions to improve safety for coastal communities. In high seas, Subsea Environmental Sensing with Operational Submarine Cables (SESOSC) has a target to create industry wide collaboration to enable early warning of tsunami. As awareness of the importance and complexity of the ocean environment becomes increasingly clear, the need for improved sensing, with better spatial resolution and increased temporal coverage, is now pressing. Submarine cables developed to transmit information between continents can be used as sensors. Sensing with submarine cables was a topic of active discussion at the SubOptic 2023 Conference, where two dozen authors presented results convincing that sensing is a powerful tool to improve cable safety but also provides opportunities for environmental monitoring.  Enormous opportunities of sensing with submarine cables are clear to many today, and need to be addressed from juridical and security perspectives. Fiber optic networks, both terrestrial and subsea, are a growing part of the information revolution. It is clear that sensing with telecom optical fibers creates a base for multiple applications, including earthquake and tsunami early warning. We discuss the next step for the submarine industry to improve cable safety and enhance environmental monitoring worldwide.

This paper contains a summary of Working Group results dedicated to DAS technology for coastal areas cable safety and environmental surveillance and sensing with trans-continental operational cables.  We discuss the strategy to facilitate applications of operational submarine cables for sensing of earthquakes, water waves, and improvement of security of submarine cables. We also plan to provide a consolidated industry viewpoint on the considerations and opportunities afforded by existing and emerging cable-based technologies for sensing the marine environment. The Working Group envisions international cooperation between cable owners and government agencies to provide low frequency data to tsunami warning centers with an early alarm threshold established based on the research project. We are working on the development of the platform  to summarize industry position on the technologies in the field of submarine cable-based environmental sensing. The Working Group does not cover the SMART submarine cables program as the Working Group deals with fiber as a sensor technologies that do not require modification of the wetplant. Optical transmission fibers are excellent sensors and operational submarine cables can provide additional value to submarine cable owners.

How to cite: Kamalov, V.: Subsea Environmental Sensing with Operational Submarine Cables, Galileo conference: Fibre Optic Sensing in Geosciences, Catania, Italy, 16–20 Jun 2024, GC12-FibreOptic-19, https://doi.org/10.5194/egusphere-gc12-fibreoptic-19, 2024.

Geothermal reservoirs require reliable well-completion techniques to reach well integrity. Well, integrity means there are no flow paths behind the casing at all. While constructing the well, the drilling mud must be fully displaced by uncontaminated cement, measured in displacement efficiency. Conventional real-time measurements show average pumping parameters to control the cement job's success. However, studies show issues with well integrity worldwide. We aim to improve well integrity by closing an information gap within the construction phase using continuous distributed fiber-optic sensing with dense spatial sampling.

This study investigated the primary cementing of an 874 m surface casing in Munich, Germany. A fiber optic cable deployed behind the casing enabled the measurement of distributed dynamic strain rate (DDSS or DAS) and distributed temperature (DTS) during cement placement. We used field data from the cementing service, developed a fluid displacement model, and compared the results with those of the fiber optics.

While we can trace only the rise of a cold front in the temperature data, the combined interpretation of DAS data shows features that allow comprehensive insights into the subsurface displacement process. We observed two rising velocities at a constant pumping rate. We were able to correlate them to the rise of different fluid interfaces. We conclude that the freshwater spacer does not displace the drilling mud but the first arrival of cement. Once the breakouts are filled, the succeeding cement seeks the path of least resistance without displacing cement in the breakouts again.

Our findings suggest the possibility of tracking the rise of different fluids and the stability of their interfaces in real-time with distributed dynamic strain sensing. Having sensors along the borehole to track the displacement efficiency enables on-site reactions to ensure the cement jobs' success.

How to cite: Hart, J., Polat, B., Schölderle, F., Ledig, T., Lipus, M., Wollin, C., Reinsch, T., and Krawczyk, C.: Closing an Information Gap in Geothermal Well Construction: Continuous Distributed Fiber-Optic Sensing for Improved Displacement Efficiency, Galileo conference: Fibre Optic Sensing in Geosciences, Catania, Italy, 16–20 Jun 2024, GC12-FibreOptic-22, https://doi.org/10.5194/egusphere-gc12-fibreoptic-22, 2024.

We present the results and current challenges of an experiment with Distributed Acoustic Sensing (DAS) on Grímsvötn volcano in Iceland, and its potential for improvements in source characterization using Full-Waveform Inversion (FWI).

We deployed a 12 km long fibre-optic cable for one month (May 2021) on Grímsvötn, Iceland’s most active volcano on a centennial time scale, which is covered by the Vatnajökull ice cap. The cable was trenched 50 cm into the ice, following the caldera rim and ending near the central point of the caldera on top of a subglacial lake.

We discover previously undetected levels of microseismicity, and we locate these events with first-arrival times and a probabilistic inversion using the Hamiltonian Monte Carlo algorithm. The ~2000 detected events have local magnitudes between -3.4 and 1.7, and their locations indicate clear clusters of activity. These appear near surface expressions of the caldera fault, such as fumaroles, and cauldrons. We use the results, combined with an initial velocity model, to set up an FWI workflow, that takes the complex topography and subsurface into account. We create the initial velocity model for the firn-ice transition by inverting a dispersion curve of the snow cat driving along the cable, and we combine this with homogeneous media for the bedrock, ice layer, and subglacial lake. We perform an initial forward modelling study for a selection of ~600 events in the frequency range of 1.5 – 3 Hz, combined with a least-squares inversion to obtain the moment tensor components of each event. Finally, we assess the resulting moment tensors and their resolution matrix in order to evaluate the potential to invert for source characteristics.

This research shows the results and potential of DAS on active subglacial volcanoes, and we hope that this research will contribute to the fields of volcano monitoring and DAS modelling.

How to cite: Klaasen, S., Noe, S., Thrastarson, S., Cubuk-Sabuncu, Y., Jónsdóttir, K., and Fichtner, A.: Moment Tensor inversion with Full-Waveform Inversion and Distributed Acoustic Sensing on a subglacial volcano: Grímsvötn, Iceland., Galileo conference: Fibre Optic Sensing in Geosciences, Catania, Italy, 16–20 Jun 2024, GC12-FibreOptic-25, https://doi.org/10.5194/egusphere-gc12-fibreoptic-25, 2024.

Scientific infrastructures cover areas worldwide to monitor Earth system processes.  Most of these are installed on land, but land masses make up only about 30% of the Earth's surface.  The oceans and particularly the ocean floor are difficult to access, and thus are not adequately instrumented and monitored.  Since they play a critical role in regulating climate as a heat and carbon store, and are the site of deadly natural disasters including strong earthquakes, tsunamis, and volcanic eruptions, we are faced with a substantial gap in the monitoring of critical physical parameters in the near-coast and offshore domains.  For seismology and geohazard assessment the global coverage is as essential as for oceanography and climate studies.  Using a combination of established and novel technologies implemented in telecommunication infrastructure on the sea-floor and coastal areas will, without a doubt, prove to be a game changer in geosciences and Earth system understanding.

In recent years, three different and complementary fiber-optics-based technologies have gained at-tention as valuable tools for investigating Earth system processes: Distributed Fiber-Optic Sensing (DFOS), State of Polarization (SoP), and Science Monitoring and Reliable Telecommunications (SMART) cable systems. The first two technologies use the fiber-optic cable as the sensing element, while in the third technology type (SMART cable systems), independent sensors are integrated into fiber-optic cable repeaters, and the cable is used for power and data transmission. These technologies and their application to geoscientific problems are at different levels of maturity, and combining them with a FAIR data infrastructure into a demonstrator is the vision of the planned infrastructure project SAFAtor (see presentation by Cotton et al., this meeting).

We want to present and discuss in the framework of our planned SAFAtor initiative (SMART Cables And Fiber-optic Sensing Amphibious Demonstrator) the first experiments we performed in the testbeds foreseen at Mt. Etna, in the Marmara Sea, and in Chile.  While Etna’s volcano-tectonic setting is complex (Jousset et al., Currenti et al.) and origin and spatial-temporal evolution of the volcanism and its relationship with the tectonic dynamics are still a matter of debate, its unstable eastern flank stretches far into the Ionian Sea with an average flank movement of 2-3 cm/yr.  In the Marmara Sea, critical data on offshore fault structure and seismicity will enable efficient investigation of structure and seismic hazard underneath densely populated areas along the coast, especially in Istanbul where the major earthquake is overdue.  This also holds for Chile, where ongoing subduction erosion and mature seismic gaps should be complemented by new monitoring efforts.  Developing our SAFAtor activities in terms of adapted fibre-optics sensing and monitoring will thus help areas exposed to hazard at active plate boundaries and volcanic systems in coastal zones.

How to cite: Krawczyk, C., Cotton, F., Tilmann, F., Wallace, L., and Team, S.: Closing the Ocean Data Gap: near-coast fibre-optics sensing to monitor tectonic and volcanic events, Galileo conference: Fibre Optic Sensing in Geosciences, Catania, Italy, 16–20 Jun 2024, GC12-FibreOptic-41, https://doi.org/10.5194/egusphere-gc12-fibreoptic-41, 2024.

The INFN-LNS (Istituto Nazionale di Fisica Nucleare – Laboratori Nazionali del Sud) operates two deep-sea cabled infrastructures in Eastern Sicily.

The first infrastructure connects a shore laboratory in the port of Catania to two underwater sites in the Gulf of Catania. This connection is made through an electro-optical submarine cable, approximately 25 km long, which hosts 10 optical fibers. At a distance of 20 km from the shore laboratory, the cable splits into two branches via a Y-junction to reach two different cable termination frames: TSN (Test Site North) and TSS (Test Site South), both located at a depth of 2100 m.

The second infrastructure is situated 100 km southeast of Portopalo di Capo Passero at a depth of 3500m. The underwater site is connected to the shore laboratory in the harbor of Portopalo via two underwater electro-optical cables. These cables carry 20 and 48 optical fibers, respectively. The second cable, funded by the IDMAR PO-FESR project, was deployed between November 2020 and November 2022. Thanks to a Y-branching unit, the cable is split underwater into two different branches.

These two LNS fiber optic infrastructures have hosted several Italian and European projects, including Geoinquire, EMSO-ERIC, IPANEMA/ECCSEL-ERIC, and FOCUS-ERC in Catania; KM3NeT and EMSO in Portopalo di Capo Passero.

Specifically, within the FOCUS-ERC and Geoinquire projects, DAS (Distributed Acoustic Sensing) and BOTDR (Brillouin Optical Time Domain Reflectometer) measurements were acquired over a long period.

The optical network of the two deep-sea infrastructures and the available assets for geoscience will be described.

How to cite: Pulvirenti, S. and Viola, S.: The INFN-LNS Fibre optic infrastructure, Galileo conference: Fibre Optic Sensing in Geosciences, Catania, Italy, 16–20 Jun 2024, GC12-FibreOptic-10, https://doi.org/10.5194/egusphere-gc12-fibreoptic-10, 2024.

Distributed Acoustic Sensing (DAS) technology is a new photonic method that can convert several tens of kilometer-long seafloor fiber-optic telecommunication cables into dense arrays of strain sensors. With such spatial and temporal resolution, DAS appears as a potential future alternative to in-situ oceanographic measurements. Nevertheless, the DAS measurement needs to be calibrated because several factors can induce modifications to the measurements such as the structure of the cable or the level of burial in the sediments. In addition, the mechanisms through which the external stresses are conveyed to the fiber are still not well understood. An initial strategy involves analyzing the response of the DAS data to surface gravity waves as these are continuously present and well-characterized signals, that can be readily measured at shallow depth. From December 2020 to January 2021, an in-situ campaign was performed which involved deploying a pressure sensor at a depth of 15 meters for nearly 2 months next to the 50 km-long LSPM (Laboratoire Sous-marin Provence Méditerranée) seafloor cable in the bay of Les Sablettes, South of France. In the frequency band of surface gravity waves, we identify a remarkable linear correlation between the energy of the pressure sensor and that of the colocated DAS sensor, for various sea conditions. This result implies that the significant wave height can be reconstructed from DAS data at all points along the telecom cable, from the coast down to the cut-off depth of linear wave theory (roughly 100 meters in that region). From the linear wave potential theory, we derive an analytical transfer function linking the cable deformation and wave kinematic parameters. Even though this transfer function provides a first quantification of the effects related to waves and the cable response, it does not allow to distinguish between the different components of the wave spectrum (long-period, infragravity, surface gravity, ultra-gravity waves...), nor acknowledge the potential contribution of temperature variations. Also, the coupling processes between water, cable, and sediment remain to be included in this transfer function. In 2023, along the same telecom cable, we deployed 6 instrumented stations along the LSPM cable for 3 months. In particular, we installed instruments to measure seafloor pressure and temperature, the velocity components in the water column, as well as variations in the depth of sediments relative to a reference. These measurements will enable us to refine the analysis of the processes involved in the DAS response. 

How to cite: Mohammedi, A., Sladen, A., Meulé, S., Pelaez-Quiñones, J., Bouchette, F., Ponte, A., and Ampuero, J.-P.: Reconstruction of nearshore surface gravity waves from Distributed Acoustic Sensing data, Galileo conference: Fibre Optic Sensing in Geosciences, Catania, Italy, 16–20 Jun 2024, GC12-FibreOptic-79, https://doi.org/10.5194/egusphere-gc12-fibreoptic-79, 2024.

Distributed Acoustic Sensing (DAS) offers unprecedented meter-scale spatial sampling of strain/strain-rate wavefields, enabling unaliased seismic event observations. DAS technology utilizes fiber optic cables (FOCs), extending seismological observations to extreme environments, including ocean floors. Given the logistical difficulties in deploying and maintaining traditional seismic stations in these contexts, seismological data near oceanic earthquake sources remain limited. On a positive note, telecommunication FOCs are often deployed on the ocean bottoms to connect urban areas on land, potentially bridging this observational gap.

Traditional seismological monitoring, which aims to locate earthquake sources, typically relies on phase picking and subsequent data inversion. In a standard seismometer network, automatically-retrieved arrival times can be manually validated by expert operators; however, this task becomes practically impossible with DAS due to the unprecedented data density it offers, which can easily reach tens of thousands channels, considering the current capabilities of interrogating cables up to 100 km. For the purpose of leveraging both data measurements close to the source (DAS) and the improved azimuthal coverage by land stations, DAS data flows must be automated. Potential solutions include accurately tuning automatic pickers for the specific FOC and/or employing data selection and weighing procedures. Recently, pickers based on machine learning have been tested for DAS as substitutes for standard pickers, offering promising results and efficient arrival time measurements. Despite these advancements, challenges persist in accurately estimating onsets due to spatial variability in DAS waveforms, arising from a) uniaxial signal polarization, b) sensitivity to site conditions, and c) heterogeneities in FOC coupling. These data uncertainties, in turn, affect event location accuracy.

We address this problem by conducting a preliminary comparison of two standard pickers (based on the actual amplitude-frequency content of each channel) with a machine-learning-derived picker. We focus on DAS recordings of six local earthquakes located on the ocean bottom between Fuerteventura and Gran Canaria islands during an experiment from November 2022 to April 2023. Each earthquake is provided with a reference location from the regional network of seismometers. Kurtosis and FilterPicker (standard pickers) and Phasenet-DAS (machine-learning picker) onsets are inverted for event location, with a focus on statistically comparing the solutions' uncertainty (scattering). To achieve this, we employed a Markov chain Monte Carlo method to estimate the Posterior Probability Densities (PPDs) of hypocentral parameters.

In a second stage, we test a data-weighing approach on absolute arrival times based on specific channel properties. The aim is to assess its effects on location PPDs, in comparison to the “not-weighed” inversion. We repurpose the same algorithm, previously used for the location comparison, to modify each entry of the covariance matrix in the Bayesian inversion scheme, thus enabling a differential weighting of the arrival times. These preliminary comparisons of the efficiency of automatic pickers and data weighting procedures are commonly employed for the evaluation of standard seismological networks. With DAS arrays, these approaches become even more crucial, given the reduced space for manual validation by experts.

How to cite: Bozzi, E., Piana Agostinetti, N., Ugalde, A., Latorre, H., Cubas Armas, M., Ventosa, S., Villaseñor, A., and Saccorotti, G.: Comparing location uncertainties with automatic pickers on DAS data: case studies from Canary Islands, Galileo conference: Fibre Optic Sensing in Geosciences, Catania, Italy, 16–20 Jun 2024, GC12-FibreOptic-17, https://doi.org/10.5194/egusphere-gc12-fibreoptic-17, 2024.

The IPANEMA project, funded under the ECCSEL-ERIC activity, aims at studying the natural emissions of carbon dioxide in the Mediterranean region via acoustic detection. In the framework of IPANEMA INFN-LNS has designed two underwater stations equipped with hydrophones and CO2 sensors: a shallow water (20 m depth) autonomous and retrievable observatory, deployed offshore the Island of Panarea (Aeolian Islands, Tyrrhenian Sea) and a cabled deep sea observatory, to be deployed in offshore the Coast of Catania at 2000 m depth (Sicily, Western Ionian Sea). Both detectors are capable to monitor the sea soundscape from a few Hz to just under 100 kHz.

In this context, INFN is investigating the possibility to use Distributed Optical Fiber sensing (DOFS) to enable the measurement of biological and anthropogenic acoustic signals along the entire length of underwater electro-optical cables. Unlike conventional sensors that measure at specific points, DOFS systems provide distributed measurements along the fiber length with high spatial sampling, allowing for dense monitoring of large structures or environments in real time. In this work, we will focus on the application of DOFS in the monitoring of biological sounds emitted by fin whales, as demonstrated by recent researches in Isfjorden Sea, Norway.

During a campaign of measurements between November 9th and 16th, 2023, IFREMER interrogated with an ASN OptoDAS two seafloor electro-optical cables of the INFN-LNS marine infrastructure in Eastern Sicily. The Distributed Acoustic Sensor (DAS) system was first connected to the LNS-INFN electro-optical cable, extending 25 km from the port of Catania to its end at approximately 2100 m water depth. Another set of measurements was carried out at the LNS-INFN Capo Passero site, using a cable extending 100 km to the shore, reaching depths of around 3500 m. In this area a research study conducted by INFN-LNS between 2012 and 2013, using hydrophones on seafloor showed the presence of fin whales.

In this work we will present the analysis of DAS signals: custom codes for data reduction, noise filtering and search for the typical fin whale calls (20 Hz intermittent pulses) will be presented and results discussed.

How to cite: Idrissi, A., Aurnia, S., Di Mauro, L. S., Pulvirenti, S., Riccobene, G., Diego-Tortosa, D., Viola, S., Sanfilippo, S., Bonanno, D., Le Pape, F., Ker, S., Murphy, S., Cappelli, G., Quetel, L., and Gutscher, M.-A.: Search for fin whale calls and shipping noise in Western Ionian Sea using Distributed Acoustic Sensor, Galileo conference: Fibre Optic Sensing in Geosciences, Catania, Italy, 16–20 Jun 2024, GC12-FibreOptic-85, https://doi.org/10.5194/egusphere-gc12-fibreoptic-85, 2024.

Distributed fiber-optic sensing (DFOS) is an emerging technique that can turn a fiber cable into a dense seismic sensor array with meter-scale spacing. Ubiquitously existing telecom fiber cables in buildings and cities render great potential for the use of DFOS in urban hazard reduction studies. One of such aspects is to identify (hidden) fault structures beneath the populated metropolis in the Taipei basin, where the NE-SW Sanchiao Fault and several basement faults transverse. While the east-dipping Sanchiao is capable of generating M 6+ earthquakes right under the urban area, its geometrical and structural characteristics are not well understood due to the absence of outcrops covered by Quaternary alluvial deposits and the lack of high-resolution seismic data. Here, we employ an existing telecommunication cable (owned by Chunghwa Telecom Company) running across the Sanchiao Fault to investigate the fault and basin structure at unprecedented resolution. The ambient noise cross-correlation and beamforming analysis are used to measure multi-frequency Rayleigh-wave phase velocities along the cable and invert for high-resolution shallow shear velocity profile across the fault. The results show a clear velocity contrast between the Taipei Basin and the Linkou Tableland, delineating a clear east-dipping geometry of the Sanchiao Fault. The presence of thick sediments to the east in the basin is also imaged to play a key role in modulating seismic waves for strong amplification and prolonged shaking. Our study evidences that the dark-fiber DFOS is a powerful direction that can offer high-resolution mapping/monitoring of the major fault structures with least cost.

How to cite: Huang, H.-H., Wang, C.-H., Wu, E.-S., Ku, C.-S., Lin, C.-J., and Ma, K.-F.: Urban hazard reduction using dark fiber distributed sensing, Galileo conference: Fibre Optic Sensing in Geosciences, Catania, Italy, 16–20 Jun 2024, GC12-FibreOptic-73, https://doi.org/10.5194/egusphere-gc12-fibreoptic-73, 2024.

Telecommunications networks based on optical fiber communication have been vastly deployed in the last years to cope with the increasing traffic demands. They cover wide terrestrial areas with thousands of kilometers of available fiber cables, arranged in meshed, rings or festoon network topologies. Moreover, their operation is becoming more and more software-defined thanks to the definition of open interfaces and data structures, transforming the infrastructure into a crucial commodity able to offer several network services.

Recently, the idea of using existing telecommunications fiber networks as a wide smart grid for environmental sensing is gaining momentum, since optical fiber can be used as an excellent mechanical stress sensors, as several physical effects are impacted by external stress. Distributed acoustic sensing (DAS) techniques deliver extremely accurate and spatially resolved measurements which are the state of the art, for example, in earthquake detection. However, its high cost, need for dark fibers and physical limitations prevent its wide deployment in telecom infrastructure.

In this context, sensing based on state of polarization (SOP) monitoring of optical signals is an attractive solution. SOP is alredy monitored on optical coherent channel receivers for data recovery, although access to this data is usually closed by transceiver vendors. However, it is potentially accessibile on cheaper intensity modulated optical data channels, still widespread in optical networks, especially in the access segment. Also, it can be monitored using dedicated signals which can be transmitted alongside typical data channels. Moreover, SOP sensing does not require bidirectional transmission onto the same fibers and can extend its reach farther than DAS as it supports optical amplifiers, thus improving the compatibility between data and sensing services. On the downside, SOP sensing loses DAS spatial resolution, as it provides an integrated measuremnts over an entire fiber span and extraction of significant event information is complicated by the randomness of fiber birefringence. However, terrestrial networks can offer several SOP sensing sites which can be implemented with far cheaper equipment with respect to DAS or interferometry.

In this work we explore the possibility for wide sensing grids with fiber length scale spatial resolution, which can integrate the information provided by traditional seismic stations networks. In particular, while developed areas may leverage on seismic stations networks, SOP sensing represents a cost effective solutio in emerging economies where telecom infrastructure is already deployed. Another key aspect relates to the development of effective techniques to detect the environemntal events of interest features, such as the earthquakes P/S waves, from the SOP time series. Indeed, especially in the terrestrial networks scenario, anthropic activities act as noise on the monitored SOP evolutions. To this aim, detection based on machine learning techniques is promising, due to the largely vaying characteristic figures of seismic waves. Due to the lack of extensive SOP experimental observations, we have developed simulations tools able to generate SOP synthetic data from realistic strain rates and we show how they can be used to train ML models based on spatially integrated SOP time evolutions.

How to cite: Virgillito, E., Awad, H., Usmani, F., Straullu, S., Bratovich, R., Proietti, R., Pastorelli, R., and Curri, V.: Environmental Sensing and Detection based on State of Polarization Monitoring in Terrestrial Optical Data Networks, Galileo conference: Fibre Optic Sensing in Geosciences, Catania, Italy, 16–20 Jun 2024, GC12-FibreOptic-8, https://doi.org/10.5194/egusphere-gc12-fibreoptic-8, 2024.

The MEGLIO project aims to observe seismic waves using coherent laser interferometry on an active telecommunication fiber network. Open Fiber, one of Italy's leading optic fiber infrastructure providers, promoted this experiment on a buried optic cable connecting Ascoli Piceno and Teramo, Italy, spanning approximately 30 km.

The cable's route, passing through roads with moderate traffic, bridges, viaducts, and urban areas, poses challenges due to anthropogenic noise. However, one of the goals of the experiment aims to demonstrate the sensitivity of the measurement technique in real-world telecommunication networks. Nevertheless, many earthquakes with Ml2+ magnitudes have been recorded at different distances from the fiber optic cable.

The physical quantity measured here is the time variation of a phase-shift, i.e. an angle. The objective of the presentation is to show the waveform signatures of seismic waves on this type of measure and their frequency spectra from a seismological perspective. We also may quantify seismological attributes such as seismic phase arrival times, frequency content, and earthquake magnitudes. Furthermore, we compare the interferometric data with traditional seismic recordings from nearby velocimeter sensors.

In essence, the MEGLIO experiment seeks to advance seismic monitoring capabilities by leveraging existing telecommunication infrastructure. Through comprehensive waveform analysis and seismological attribute measurement, valuable insights into earthquake characteristics can be obtained, contributing to improved our seismic monitoring efforts.

How to cite: Herrero, A., Govoni, A., Margheriti, L., Vassallo, M., donatello, S., Clivati, C., Brenda, D., Hovsepyan, M., Bertacco, E., Concas, R., Levi, F., Mura, A., Carpentieri, F., and Calonico, D.: Advancing Seismic Monitoring using Interferometric Data Recorded on Telecom Fiber Networks, Galileo conference: Fibre Optic Sensing in Geosciences, Catania, Italy, 16–20 Jun 2024, GC12-FibreOptic-43, https://doi.org/10.5194/egusphere-gc12-fibreoptic-43, 2024.

The ubiquitous optical fiber infrastructure already installed for telecommunications purposes represents a precious asset for pervasive sensing.  The telecom fiber plan can be used not only for controlling the network integrity itself, but also for monitoring the road traffic, for large breaches and damages detection in civil structures, for the supervision of utilities health, and for the prompt detection of seismic and natural hazards.  Nowadays, systems based on distributed acoustic sensing (DAS) are successfully applied also in telecom links, to provide measurements with very high resolution and spatial accuracy in localization. In particular, DAS systems appear very attractive to operate as fiber seismometers for early earthquake detection. However, DAS back-scattering approach requires complex and expensive DSP and storage of a huge amount of data, not generally compatible with the budget of large-scale sensing applications. Interferometric solutions constitute a possible alternative, but usually they employ ultra-stable laser sources, characterized by laser coherence length longer than the sensing fiber to monitor.

For extensive applications of optical sensing in the pervasive fiber telecom infrastructure, sustainable in terms of cost, energy efficiency and reliability, we propose to adopt the interferometric approach, but constructing the interferometer itself directly embedded inside the multi-fiber telecom cable, where two fiber operate as interferometric arms. No stringent requirement is necessary for the laser sources and typical telecom DFB lasers are employed together with a simple detection scheme.

In this paper we show how the proposed “in-cable” sensor is used over the deployed telecom network to monitor geo-hazards. In particular, its operation to detect risks of landside affecting the safety of a railway in the north side of the Lake Iseo, Lombardia is presented. Two standard single-mode fibers of the 48-fiber telecom cable installed in a conduit under the sidewalk running alongside the railroad tracks by an Italian operator are employed to realize the sensor. Not only traffic events such as travelling trains, car passages on a railroad crossings and pedestrians crossing the track are detected, but above all the fall of rocks obstructing the tracks are identified. Suitable machine-learning allows to classify and discriminate dangerous events for the safety of the railway from nuisances caused by the noisy and hostile environment, that can be sources of annoying false alarms. Providing integral measurements, this interferometric sensor does not localize the event, but gives early warning of possible risks for the railway, detecting in real time landslides and notifying the alarm in a proactive way.  Other applications related to the monitoring of tunnels and viaducts, river embankments and shallow landslides triggered by rainfalls are also demonstrated.

This work was partially supported by the Italian Government through project PRIN 2022 SURENET and by the European Union under the Italian National Recovery and Resilience Plan (NRRP) of NextGeneration EU, partnership on “Telecommunications of the Future” (PE00000001 - program “RESTART”) in the project SENSING NET.

How to cite: Morosi, J., Brunero, M., Ferrario, M., Fasano, M., Madaschi, A., and Boffi, P.: Landside hazards detection by interferometric sensor over deployed telecom fibers for railway safety surveillance, Galileo conference: Fibre Optic Sensing in Geosciences, Catania, Italy, 16–20 Jun 2024, GC12-FibreOptic-74, https://doi.org/10.5194/egusphere-gc12-fibreoptic-74, 2024.

This article delves into the concept of Network Sensing, first by revisiting sensor networks and telecommunications networks (Telco networks) and analyzing the informational content they convey.

Sensor networks interconnect sensor devices designed to measure physical quantities, yielding unintentional informational content from monitored events like temperature, pressure, light, motion, vibrations, and other environmental or industrial parameters.

Conversely, Telco networks, whether human-to-human, human-to-machine, or machine-to-machine, transport intentional informational content such as voice, data, and video.

Sensor networks exhibit a variable and distributed geometry, adaptable to monitored events or areas, allowing for flexible sensor density and distribution based on specific application needs. In contrast, Telco networks feature a predefined and structured geometry with specific connection points (e.g., cell towers, telephone exchanges, network nodes), ensuring reliable coverage and reach, optimized for data flow and service quality.

This difference in network geometry requires precise connection points for Telco networks (e.g., individuals, cities, nations, servers, clouds), while the geometry of sensor networks depends on events, sometimes necessitating a uniform and costly distribution due to event dispersion.

Traditionally, overlaying these networks results in cost duplication, hindering the development of techniques that, while advantageous in measured scale, lack economic efficiency.

Projects like Meglio [1] aim to reuse Telco infrastructure and geometry for event collection, such as seismic activities. The convergence of sensor and Telco networks introduces Network Sensing, explored in 6G wireless networks and recently implemented in fiber optic networks for applications like seismic alarms. This convergence could halve implementation costs, rendering initiatives sustainable. However, the effectiveness in measuring certain events requires further analysis through future experimentation.

Reference

[1] Simone Donadello et al.: Earthquake observatory with coherent laser interferometry on the telecom fiber network , arXiv:2307.06203v1 [physics.geo-ph] 12 Jul 2023

How to cite: Carpentieri, F., Hovsepyan, M., and Brenda, D.: Exploring Network Sensing for Cost-Effective Event Detection, Galileo conference: Fibre Optic Sensing in Geosciences, Catania, Italy, 16–20 Jun 2024, GC12-FibreOptic-53, https://doi.org/10.5194/egusphere-gc12-fibreoptic-53, 2024.

Many cities worldwide are threatened by flooding and sea level rise because of climate change. Early detection of potential threats is essential for safeguarding human lives and housing, as well as critical infrastructures. Continuous monitoring of the subsurface by analysis of surface waves recorded by roadside DAS systems that exploit preexisting telecommunication fibers can provide useful information at a low cost. In urban areas, vehicles transiting on city streets generate large amounts of broad-band (2-25 Hz) surface waves that propagate in the subsurface and can be readily used for continuous monitoring. We designed and successfully tested a targeted interferometry workflow capable of generating high signal-to-noise (SNR) virtual source gathers.

The first step in our workflow is to identify the path of vehicles transiting on roads close to the fiber cable. That can be accomplished by following the low-frequency strain signal caused by the quasi-static elastic deformation of the ground. The path is tracked using an algorithm based on Kalman filters. Because long and heavy vehicles generate lower frequency surface waves, we could also perform space deconvolution of the quasi-static signal to estimate the vehicle length and number of axels to improve the signal-to-noise ratio (SNR) at low frequencies. The second step is to perform targeted seismic interferometry in the time-space windows where the surface waves generated by the tracked vehicles are strongest. We found that about two hundred vehicles were sufficient to synthesize high SNR virtual source gathers. The temporal resolution of the measurements is thus of the order of hours, depending on traffic intensity and the SNR required by the specific monitoring application. We used the virtual gathers to generate phase and group velocity profiles. We also measured the amplitude decay as a function of offsets and frequencies to estimate surface-wave attenuations. The analysis of DAS data continuously recorded before, during, and after the heavy rains in California during the 2022-23 winter showed that seismic velocities decreased and attenuation increased as the rains saturated the ground, and they rebounded as the ground dried up. The reliability and high spatial-resolution of the measurements (order of tenth of meters) also enabled us to observe the difference in the seismic response between paved and lawn areas.

How to cite: Biondi, B. and Yuan, S.: Monitoring changes in subsurface seismic properties caused by heavy rains with a roadside DAS by targeted interferometry, Galileo conference: Fibre Optic Sensing in Geosciences, Catania, Italy, 16–20 Jun 2024, GC12-FibreOptic-42, https://doi.org/10.5194/egusphere-gc12-fibreoptic-42, 2024.

Ambient noise interferometry applied to Distributed Acoustic Sensing (DAS) arrays is an increasingly common approach to subsurface investigations. In this study, we show that analysis of urban seismic noise acquired on a DAS array can be used to track velocity variations caused by groundwater level changes in an alluvial aquifer.

We apply our methodology to the Crépieux-Charmy aquifer, a strategic site for the city of Lyon, France. This site provides more than 90% of the city's drinking water and uses a Managed Aquifer Recharge (MAR) system, which allows controlled recharge of the aquifer through infiltration basins. We analyzed four weeks of DAS ambient noise data recorded on a 3 km spiral DAS array surrounding an infiltration basin.  During this period, a controlled water infiltration experiment was conducted by the site operators. 

We used traffic noise in the 2-5 Hz frequency band and performed DAS-based time-lapse surface wave tomography of velocity variations in the area. We were then able to map relative changes in seismic velocity in the vadose zone. Comparison of point-scale water level measurements from piezometers and adjacent cells in the velocity variation maps shows good agreement between the two observables. These velocity variations are directly related to the water table variations and to residual water saturation changes within the unsaturated zone.

This pilot application demonstrates the potential for groundwater monitoring in aquifer systems using DAS combined with seismic interferometry.

How to cite: Nziengui Bâ, D., Coutant, O., Jestin, C., and Lanticq, V.: Monitoring groundwater dynamics in the Crepieux-Charmy water catchment using DAS-based surface wave tomography, Galileo conference: Fibre Optic Sensing in Geosciences, Catania, Italy, 16–20 Jun 2024, GC12-FibreOptic-55, https://doi.org/10.5194/egusphere-gc12-fibreoptic-55, 2024.

The vulnerability of urban assets, encompassing soils, buildings, and infrastructure, is intricately linked to human activities, environmental exposure, and societal vulnerabilities. By employing Distributed Acoustic Sensing (DAS) technology on telecom fiber networks, we have developed an information model that facilitates data extraction, exchange, and networking to enhance decision-making regarding civil engineering assets. In collaboration with the APRR-AREA French company, our focus lies on two long-span bridges situated along a 25 km stretch of telecom optic fiber on the A40 motorway concession — known as the "autoroute des Titans" — in eastern France. Our objective is to characterize the deformation of these structures under heavy vehicle traffic, aiming at discerning behavioral disparities between spans and identifying potential plasticization zones. Employing a standard beamforming approach, we track vehicles using DAS data records. A statistical analysis of signal amplitudes helps to establish standard deformation thresholds and to detect anomalous deformation events. We conduct diagnostics to identify the origins of these events through DAS signals identification and classification. Simultaneously, we continuously monitor the vibrational characteristics of the structures, including frequencies, damping, and modal shapes, to ascertain if traffic-induced deformations enter the plastic regime. Throughout the 68-hour acquisition campaign, we tracked 5 423 vehicles with weight ranging from 2 568 to 73 123 kilograms. On one of the bridges, our analysis revealed 402 events exceeding the 5-sigma threshold, 58 surpassing the 10-sigma threshold, 33 exceeding the 12-sigma threshold, and 4 surpassing the 15-sigma threshold. We will analyse if these events coincide temporally and spatially with those detected with conventional long-base extensometers deployed all along the bridge deck. There is no indication of plastic deformation. This study highlights the potential of utilizing DAS technology applied to telecom optic fibers to complement specialized instrumentation for monitoring the behavior of long-span bridges.

How to cite: Rodet, J., Tauzin, B., Amin Panah, M., and Pittet, R.: Urban Dark Fiber Distributed Acoustic Sensing for Bridge Monitoring under Road Traffic Sollicitation, Galileo conference: Fibre Optic Sensing in Geosciences, Catania, Italy, 16–20 Jun 2024, GC12-FibreOptic-39, https://doi.org/10.5194/egusphere-gc12-fibreoptic-39, 2024.

Multiple input multiple output (MIMO) distributed fiber Sensing (DFS) is an innovative digital approach to phase-OTDR derived from technologies used in long-haul transmission over both terrestrial and submarine telecom networks. The probing signal is composed of digital codes that modulate in phase a highly coherent laser source over two orthogonal polarization axes, and the Rayleigh backscattered optical field is captured by a coherent mixer set in a homodyne configuration. This technique estimates, after digital processing, the backscattered signal without polarization fading effect and under a Jones matrix form, so giving access to the intensity, the local phase and the state of polarization along the fiber link under test. The link is continuously probed, which allows to monitor the local phase changes induced by mechanical events occurring in the fiber vicinity over a maximal bandwidth given by length of the monitored fiber link. We demonstrated the MIMO-DFS capabilities over links up to 100km with a gauge length of 10 meters and a capture of events linearly to disturbance pressure, in a microphone-like way, over a 200Hz bandwidth.  The detection threshold, or noise floor, increases along the fiber length and was shown to be drastically lowered compared with standard DFS techniques which probe the fiber over one polarization axis only. The 100km figure achieved will be further improved soon by enhancing the stability of the laser source.

The MIMO-DFS technique has been designed to be compliant with telecom networks in a way so that a fiber can be monitored using one WDM channel without impacting the traffic rate propagating over adjacent WDM channels. We recently conducted a field trial using a telecom operator active network in Saudi Arabia. The purpose was to early detect mechanical threats that may lead to a traffic disruption. We provoked mechanical events by means of jackhammer and excavator in the vicinity of a 57km deployed cable buried two meters depth, both in a city area and in the desert, at distance of 15 and 30km from the fiber start respectively.  The aim of the paper is to highlight the ability to detect, localize and even recognize the various noise sources under test in the context of a realistic deployed network, thanks to the outstanding sensitivity of the sensing technique. Beyond early detection of human induced threats for telecom networks integrity, the MIMO-DFS approach is also suited to detect much more critical environmental threats such as seisms with potential impact on people safety.

How to cite: Dorize, C.: MIMO-DFS for detection-localization-identification of mechanical threats over existing telecom networks, Galileo conference: Fibre Optic Sensing in Geosciences, Catania, Italy, 16–20 Jun 2024, GC12-FibreOptic-46, https://doi.org/10.5194/egusphere-gc12-fibreoptic-46, 2024.

In the last few years, a number of technologies to use fiber optic cables as sensing devices have been established, among them Distributed Acoustic Sensing (DAS) and State-of-Polarisation (SoP). The potential of these technologies for monitoring a range of Earth System parameters in submarine cables has been demonstrated through several pilot experiments, but full integration with telecommunication infrastructure has not yet been achieved. The SUBMERSE (SUBMarinE cables for ReSearch and Exploration) project links Research and Education Networks (RENs), universities, research institutes and industry to establish multi-method monitoring along submarine optical telecommunication cables at several key oceanic cable routes branching off from Sines in Portugal, Madeira, Svalbard and in the Ionian Sea, and in addition the Transatlantic cable between Fortaleza and Sines. Those pilot sites should serve as a blueprint for establishing continuous monitoring services along many more cables.

The project comprises technical developments for integrating DAS and SoP measurements, for establishing differential SoP measurements between repeaters and for operating DAS in a co-existence mode, i.e., in fibers also carrying telecommunications traffic. Furthermore, a range of geoscientific and marine biology use cases are included, which seek to establish code/services for monitoring earthquakes and tsunamis, tracking whales, measuring the sea state and other Earth System variables. The data collected by SUBMERSE will be distributed according to FAIR principles through established community-specific distribution channels such as EIDA for seismological data, with exceptions for security sensitive time periods, spatial or frequency ranges.

The presentation will present some example data and methodological developments in the context of this project. Furthermore, an outlook on the seismological real-time and archive products will be provided.

How to cite: Tilmann, F., Atherton, C., Asero, C., Evangelidis, C., Charalampakis, M., Landrø, M., Rondenay, S., Ottemöller, L., Maji, V., Corela, C., Matias, L., Custódio, S., Schlaphorst, D., Strollo, A., Xiao, H., Papapostolou, A., Perivoliotis, L., Morten, J. P., Heinloo, A., and Loureiro, A. and the SUBMERSE WP3 team (additional members): Towards continuous fibre-optic monitoring in the oceans with submarine telecommunications cables – the SUBMERSE project, Galileo conference: Fibre Optic Sensing in Geosciences, Catania, Italy, 16–20 Jun 2024, GC12-FibreOptic-31, https://doi.org/10.5194/egusphere-gc12-fibreoptic-31, 2024.

SAFAtor is planned as a major infrastructure project (30 millions Euros) of the German Helmholtz Association which aims at effectively closing the observational gap in the continental shelf, slope, and deep oceans by using new cable technologies.  SAFAtor (SMART Cables And Fiber-optic Sensing Amphibious Demonstrator) will have three main outcomes: 1) SAFAtor will establish DAS permanent offshore monitoring at three existing Plate Boundary Observatories located in coastal areas (Northern Chile, the Marmara Sea and Etna volcano, see the presentation of Krawczyk et al.). This integration will build on outcomes from the European SUBMERSE project (to finish in 2026) and will enable unprecedented monitoring of tectonic and volcanic events (landslides, observation of the preparation phase of strong earthquakes on submarine faults close to the coast, new early warning systems for earthquakes and tsunamis, and submarine volcanic processes).  2) SAFAtor will provide a working demonstrator by equipping a submarine telecommunication cable with robust sensor technology packages to measure temperature, absolute pressure and ground acceleration on the sea floor. The location of the demonstrator cable will be discussed with the international community and chosen to maximize scientific exploitation. 3) SAFAtor will finally develop a FAIR infrastructure necessary to process, archive and distribute these new DAS and cable data, and enable the global user community to select and process the data services in a user-friendly and interoperable way. The development of these novel DAS data management strategies has already started (EU project GeoInquire https://www.geo-inquire.eu). This new data infrastructure will be integrated into national German data services (Helmholtz Data-Hub, NFDI4Earth) and contribute to European data infrastructures (e.g., EPOS, EMSO, Copernicus Marine Services). Such new infrastructure and data services have the potential to profoundly change geohazards warning systems, ocean and marine life observations and revolutionize the development of models used to analyze and predict climate change and the variability of ocean currents.

How to cite: Cotton, F., Krawczyk, C., Tilmann, F., Wallace, L., and team, T. S.: Closing the Ocean Data Gap by combined fibre-optics, SMART cable sensing and novel data management strategies., Galileo conference: Fibre Optic Sensing in Geosciences, Catania, Italy, 16–20 Jun 2024, GC12-FibreOptic-35, https://doi.org/10.5194/egusphere-gc12-fibreoptic-35, 2024.