REVIEW 2 minor 15 references
Per-Span Microwave Frequency Fiber Interferometry in Subsea Cables for Scalable Deep-Ocean Geophysical Monitoring
T0 review · 0 major / 2 minor · reviewed 2026-06-26 · grok-4.3
Pith's one-line read Microwave frequency fiber interferometry monitors a 1,770 km subsea cable and resolves tides, storms, and teleseismic earthquakes.
desk verdict The paper reports a working per-span microwave interferometry setup on a real 1770 km operational subsea cable that tracked tides, storms, and teleseismic events over four months. read the letter →
The pith
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
The reading
What carries the argument
Per-span microwave frequency fibre interferometry, which detects small length changes in individual fiber spans through phase shifts in microwave-modulated light.
What would settle it
Independent verification with co-located ocean-bottom seismometers or pressure sensors on the same cable route that either matches or fails to match the interferometry traces for the same events.
Extended reading notes
Core claim
The authors establish that microwave frequency fibre interferometry applied per span on a 1,770 km operational subsea cable successfully resolves tidal variations, storms, and teleseismic earthquakes over four months of continuous operation.
Load-bearing premise
The recorded signals arise from the claimed geophysical sources rather than from instrumental noise, temperature changes, or unrelated cable motion.
Editorial extensions
If this is right
- Existing subsea cables can be turned into dense arrays for continuous ocean-floor monitoring.
- Teleseismic events become observable with spatial resolution set by individual cable spans.
- Large-scale geophysical networks become feasible at far lower cost than dedicated sensor installations.
- Storm and tidal signals provide additional calibration data alongside earthquake detections.
Reading between the lines
- The method could be applied to the global network of subsea cables for basin-scale ocean monitoring.
- Temperature compensation techniques might be added later to reduce false signals without changing the core interferometry.
- Combining per-span data with existing cable fault location systems could create hybrid geophysical and operational monitoring.
Signed reviews
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The manuscript presents a demonstration of per-span microwave frequency fiber interferometry on a 1,770 km operational subsea cable between Ireland and Iceland. Over four months, the technique is shown to resolve tidal variations, storms, and teleseismic earthquakes, positioning it as a scalable, low-cost method for deep-ocean geophysical monitoring.
Significance. This work has the potential to significantly impact ocean monitoring by utilizing existing subsea cables for geophysical data collection. The ability to monitor per-span on long cables could provide unprecedented spatial resolution for detecting environmental and seismic events, complementing traditional methods. The four-month operational demonstration strengthens the case for practical deployment.
minor comments (2)
- Ensure that all figures include clear labels for time series comparisons with external references such as tide gauges and seismic catalogs.
- Provide more detail on the data processing steps to allow reproducibility of the phase time series extraction.
Simulated Author's Rebuttal
We thank the referee for the positive summary, significance assessment, and recommendation of minor revision. No specific major comments were provided in the report.
Circularity Check
No significant circularity; experimental demonstration relies on external references
full rationale
The paper is an empirical demonstration of per-span interferometry on an operational subsea cable, with results validated by direct comparison of phase time series against independent external datasets (tide gauges, weather records, global seismic catalogs). No derivations, equations, fitted parameters, or self-citation chains are present that reduce any claim to its own inputs by construction. The central attribution of signals to geophysical sources is supported by cross-validation with outside benchmarks rather than internal redefinition or ansatz smuggling.
Assumptions & free parameters
Cite this review
Pith. "Pith review of Per-Span Microwave Frequency Fiber Interferometry in Subsea Cables for Scalable Deep-Ocean Geophysical Monitoring." pith.science (2026). https://pith.science/paper/B3HCBOSV
@misc{pith2026260621905,
author = {Pith},
title = {Pith review of: Per-Span Microwave Frequency Fiber Interferometry in Subsea Cables for Scalable Deep-Ocean Geophysical Monitoring},
year = {2026},
howpublished = {\url{https://pith.science/paper/B3HCBOSV}},
note = {Machine review of arXiv:2606.21905}
}
read the original abstract
We demonstrate low-cost microwave frequency fibre interferometry for per-span monitoring of a 1,770 km operational subsea cable connecting Ireland and Iceland. Over four months, this approach successfully resolved tidal variations, storms, and teleseismic earthquakes, highlighting its potential for large-scale, cost-effective ocean monitoring.
Reference graph
Works this paper leans on
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[1]
Celli2, David Craig2, Örn Jónsson3, Andrés Arnar Hlynsson3, Eoin Kenny4, Charis Mesaritakis5, Christopher J
Per-Span Microwave Frequency Fiber Interferometry in Subsea Cables for Scalable Deep-Ocean Geophysical Monitoring Georgios Aias Karydis1, Nicolas L. Celli2, David Craig2, Örn Jónsson3, Andrés Arnar Hlynsson3, Eoin Kenny4, Charis Mesaritakis5, Christopher J. Bean2 and Adonis Bogris1 (1)Dept. of Informatics and Computer Engineering, University of West Attic...
2026
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[2]
is very practical but has limited sensitivity compared to phase interrogation tech-niques. OFDR based per-span interferometry is really efficient and has been shown to be capable of global seismic monitoring [4], however it re-quires a high-quality fibre laser, high performance and high-speed digital electronics (~ Gsps) and GPU processing which increase ...
2000
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[3]
The first example is the detection of tele-seismic waves generated by the 08/12/2025 Mw 7.6 Hok-kaido earthquake and 01/04/2026 Mw 7.4 Indo-nesia earthquake
In this period, it success-fully demonstrated its ability to detect a large va-riety of geophysical processes in the ocean. The first example is the detection of tele-seismic waves generated by the 08/12/2025 Mw 7.6 Hok-kaido earthquake and 01/04/2026 Mw 7.4 Indo-nesia earthquake. Fig. 2 shows that, for both earthquakes, surface waves are clearly detected...
2025
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[4]
The tidal signal is also strongest on spans 3, 4 and 8, which are closest to steep bathymetric gradients in the Rockall ba-sin, which can suggest stronger sea-bottom cur-rents
All spans (filtered 0.00001-1 Hz) record the tidal signal clearly (bottom panel, with chan-nels sorted by their distance from Galway), and a comparison with real ocean tide height measured at Galway Port (blue) to channels 1, 3 of the MFFI (red and black, respectively) with patterns show-ing excellent agreement. The tidal signal is also strongest on spans...
2026
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[5]
and the stability of offshore deep-water slopes. Our demonstrated ability to measure offshore (>100 km from coastlines) long-period ocean-floor pressure fluctuations may also offer significant potential for global tsu-nami early-warning systems. Conclusions We present per-span MFFI results from a subsea cable linking Iceland and Ireland, demonstrating sen...
2026
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[6]
DOI: 10.1109/ECOC66593.2025.11263003
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[7]
DOI: 10.23919/OECC/PSC62146.2025.11110694
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[8]
DOI: 10.1126/sci-ence.abo1939
Show all 15 references
Reviewed June 26, 2026 · model on record in the stance chip above.
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