Microwave frequency dissemination systems as sensitive and low-cost interferometers for earthquake detection on commercially deployed fiber cables

Bogris, Adonis; Simos, Christos; Simos, Hercules; Νίκας, Θωμάς; Melis, Νikolaos S.; Lentas, Konstantinos; Mesaritakis, Charis; Chochliouros, Ioannis P.; Lessi, Christina

doi:10.1364/ofc.2022.m2f.4

Cited by 3 publications

(11 citation statements)

References 4 publications

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“…Integrated strain sensing systems, such as the MFFI system designed by Bogris et al. (2021), are especially exciting in the context of pre‐existing telecommunications fibers already connecting our cities. The fact that it can be deployed cheaply and using live telecommunications networks means multiple systems could quickly blanket large regions of the Earth’s surface.…”

Section: Discussionmentioning

confidence: 99%

“…The total length of fiber used for the DAS measurements was roughly 24 km, while the transmission‐based system followed the same path and then was looped back to return to the starting location. This extra travel path is accounted for when converting optical phase delays to strain rate (Bogris et al., 2021).…”

Section: Experimental Comparison Of Integrated and Distributed Sensingmentioning

confidence: 99%

“…In September and October of 2021, we ran a Silixa iDAS interrogator alongside the MFFI system of Bogris et al. (2021) in northern Athens, Greece, in collaboration with the Hellenic Telecommunications Organization (in Greek: OTE). A number of earthquakes were observed, including both local and regional‐scale events.…”

Section: Introductionmentioning

confidence: 99%

“…Recently, Bogris et al. (2021) installed one such system in a suburban region of Athens, using pre‐existing telecommunications fiber. Their particular system relies on the interferometric use of microwave‐range frequencies‐signals sent along the fiber and back in a closed loop are compared to what was sent and phase differences are measured.…”

Section: Introductionmentioning

confidence: 99%

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Linking Distributed and Integrated Fiber‐Optic Sensing

Bowden

Fichtner

Νίκας

et al. 2022

Geophysical Research Letters

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Distributed Acoustic Sensing (DAS) has become a popular method of observing seismic wavefields: backscattered pulses of light reveal strains or strain rates at any location along a fiber‐optic cable. In contrast, a few newer systems transmit light through a cable and collect integrated phase delays over the entire cable, such as the Microwave Frequency Fiber Interferometer (MFFI). These integrated systems can be deployed over significantly longer distances, may be used in conjunction with live telecommunications, and can be significantly cheaper. However, they provide only a single time series representing strain over the entire length of the fiber. This work discusses theoretically how a distributed and integrated system can be quantitatively compared, and we note that the sensitivity depends strongly on points of curvature. Importantly, this work presents the first results of a quantitative, head‐to‐head comparison of a DAS and the integrated MFFI system using pre‐existing telecommunications fibers in Athens, Greece.

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Section: Discussionmentioning

confidence: 99%

Section: Experimental Comparison Of Integrated and Distributed Sensingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Linking Distributed and Integrated Fiber‐Optic Sensing

Bowden

Fichtner

Νίκας

et al. 2022

Geophysical Research Letters

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“…In this work, we present in detail a new sensing technique accomplishing the detection of geophysical effects with the use of optical transmission over long distances 32 . It relies on the dissemination of a microwave frequency modulating optical carriers along a fiber link in a closed-loop configuration as depicted in Fig.…”

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confidence: 99%

Sensitive seismic sensors based on microwave frequency fiber interferometry in commercially deployed cables

Bogris

Νίκας

Simos

et al. 2022

Sci Rep

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The use of fiber infrastructures for environmental sensing is attracting global interest, as optical fibers emerge as low cost and easily accessible platforms exhibiting a large terrestrial deployment. Moreover, optical fiber networks offer the unique advantage of providing observations of submarine areas, where the sparse existence of permanent seismic instrumentation due to cost and difficulties in deployment limits the availability of high-resolution subsea information on natural hazards in both time and space. The use of optical techniques that leverage pre-existing fiber infrastructure can efficiently provide higher resolution coverage and pave the way for the identification of the detailed structure of the Earth especially on seismogenic submarine faults. The prevailing optical technique for use in earthquake detection and structural analysis is distributed acoustic sensing (DAS) which offers high spatial resolution and sensitivity, however is limited in range (< 100 km). In this work, we present a novel technique which relies on the dissemination of a stable microwave frequency along optical fibers in a closed loop configuration, thereby forming an interferometer that is sensitive to deformation. We call the proposed technique Microwave Frequency Fiber Interferometer (MFFI) and demonstrate its sensitivity to deformation induced by moderate-to-large earthquakes from either local or regional epicenters. MFFI signals are compared to signals recorded by accelerometers of the National Observatory of Athens, Institute of Geodynamics National Seismic Network and by a commercially available DAS interrogator operating in parallel at the same location. Remarkable agreement in dynamical behavior and strain rate estimation is achieved and demonstrated. Thus, MFFI emerges as a novel technique in the field of fiber seismometers offering critical advantages with respect to implementation cost, maximum range and simplicity.

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Dual wavelength microwave frequency fiber interferometer system for distributed localization based on time delay estimation

Hu,

Li,

Zhang

et al. 2024

Advanced Fiber Laser Conference (AFL2023)

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Distributed optical fiber sensors have the advantages of corrosion resistance, anti-electromagnetic interference and adaptability to extreme environments. They can be used in perimeter security, pipeline monitoring, seismic detection and other fields. A novel optical fiber sensor called microwave frequency fiber interferometer has been proposed for low frequency sensing applications such as submarine seismic monitoring. However, the MFFI can only achieve integrated sensing and cannot achieve distributed localization of disturbances. In order to solve the problem that MFFI cannot achieve distributed localization and make it more suitable for long distance sensing applications, we propose a dual wavelength MFFI system based on wavelength division multiplexing to achieve distributed localization through time delay estimation algorithm. Our proposed system and algorithm make up for the inability of MFFI to achieve distributed localization and can be used in more sensing applications.

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Microwave frequency dissemination systems as sensitive and low-cost interferometers for earthquake detection on commercially deployed fiber cables

Abstract: We experimentally demonstrate a microwave frequency dissemination system operating as a sensitive interferometric sensor of seismic waves on commercially deployed fiber networks in Attika, Greece. Efficient detection of seismic waves from distant epicenters (>400km) is presented

Cited by 3 publications

References 4 publications

Linking Distributed and Integrated Fiber‐Optic Sensing

Linking Distributed and Integrated Fiber‐Optic Sensing

Sensitive seismic sensors based on microwave frequency fiber interferometry in commercially deployed cables

Dual wavelength microwave frequency fiber interferometer system for distributed localization based on time delay estimation

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