Analysis of a Local Earthquake in the Arctic Using a 120 KM Long Fibre-Optic Cable

Rørstadbotnen, Robin André; Landrø, Martin; Taweesintananon, Kittinat; Bouffaut, Léa; Potter, John R.; Johansen, Ståle Emil; Kriesell, Hannah Joy; Brenne, Jan Kristoffer; Haukanes, Aksel; Schjelderup, Olaf; Storvik, Frode

doi:10.3997/2214-4609.202210404

Cited by 2 publications

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“…We observe different wave types (compressional and shear) excited in the ocean sub-bottom that correspond to these seismic events as described in Saito & Tsushima 30 . As in previous studies [3][4][5][6] , our DAS analysis shows a rich expression of natural features, from 0.01-20 Hz, capturing not only the range and direction of earthquake hypocentres, but also the effect of deeper-diving waves passing through regions of higher velocity, and the interaction with local bathymetry 31 . We demonstrate that source localisation, exploiting the long array with a massive number of sensing points, represents a valuable complement to conventional methods.…”

Section: Resultssupporting

confidence: 74%

Sensing whales, storms, ships and earthquakes using an Arctic fibre optic cable

Landrø

Bouffaut

Kriesell

et al. 2022

Sci Rep

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Our oceans are critical to the health of our planet and its inhabitants. Increasing pressures on our marine environment are triggering an urgent need for continuous and comprehensive monitoring of the oceans and stressors, including anthropogenic activity. Current ocean observational systems are expensive and have limited temporal and spatial coverage. However, there exists a dense network of fibre-optic (FO) telecommunication cables, covering both deep ocean and coastal areas around the globe. FO cables have an untapped potential for advanced acoustic sensing that, with recent technological break-throughs, can now fill many gaps in quantitative ocean monitoring. Here we show for the first time that an advanced distributed acoustic sensing (DAS) interrogator can be used to capture a broad range of acoustic phenomena with unprecedented signal-to-noise ratios and distances. We have detected, tracked, and identified whales, storms, ships, and earthquakes. We live-streamed 250 TB of DAS data from Svalbard to mid-Norway via Uninett’s research network over 44 days; a first step towards real-time processing and distribution. Our findings demonstrate the potential for a global Earth-Ocean-Atmosphere-Space DAS monitoring network with multiple applications, e.g. marine mammal forecasting combined with ship tracking, to avoid ship strikes. By including automated processing and fusion with other remote-sensing data (automated identification systems, satellites, etc.), a low-cost ubiquitous real-time monitoring network with vastly improved coverage and resolution is within reach. We anticipate that this is a game-changer in establishing a global observatory for Ocean-Earth sciences that will mitigate current spatial sampling gaps. Our pilot test confirms the viability of this ‘cloud-observatory’ concept.

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Section: Resultssupporting

confidence: 74%

Sensing whales, storms, ships and earthquakes using an Arctic fibre optic cable

Landrø

Bouffaut

Kriesell

et al. 2022

Sci Rep

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“…Such a systematic search computes the travel time for all possible locations in a survey area to find the best matching source location. This kind of GS procedure has been adapted from earthquake seismology (see, e.g., Havskov and Ottemoller (2010)) and it has been previously applied to earthquakes recorded on DAS arrays by Rørstadbotnen et al (2022). GS methods are also commonly used for whale localization (see, e.g., Wilcock (2012); Abadi et al (2017)).…”

Section: Grid Search Position Estimationmentioning

confidence: 99%

Simultaneous tracking of multiple whales using two fiber-optic cables in the Arctic

et al. 2023

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Climate change is impacting the Arctic faster than anywhere else in the world. As a response, ecosystems are rapidly changing. As a result, we can expect rapid shifts in whale migration and habitat use concurrent with changes in human patterns. In this context, responsible management and conservation requires improved monitoring of whale presence and movement over large ranges, at fine scales and in near-real-time compared to legacy tools. We demonstrate that this could be enabled by Distributed Acoustic Sensing (DAS). DAS converts an existing fiber optic telecommunication cable into a widespread, densely sampled acoustic sensing array capable of recording low-frequency whale vocalizations. This work proposes and compares two independent methods to estimate whale positions and tracks; a brute-force grid search and a Bayesian filter. The methods are applied to data from two 260 km long, nearly parallel telecommunication cables offshore Svalbard, Norway. First, our two methods are validated using a dedicated active air gun experiment, from which we deduce that the localization errors of both methods are 100 m. Then, using fin whale songs, we demonstrate the methods' capability to estimate the positions and tracks of eight fin whales over a period of five hours along a cable section between 40 and 95 km from the interrogator unit, constrained by increasing noise with range, variability in the coupling of the cable to the sea floor and water depths. The methods produce similar and consistent tracks, where the main difference arises from the Bayesian filter incorporating knowledge of previously estimated locations, inferring information on speed, and heading. This work demonstrates the simultaneous localization of several whales over a 800 km area, with a relatively low infrastructural investment. This approach could promptly inform management and stakeholders of whale presence and movement and be used to mitigate negative human-whale interaction.

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Analysis of a Local Earthquake in the Arctic Using a 120 KM Long Fibre-Optic Cable

Cited by 2 publications

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Sensing whales, storms, ships and earthquakes using an Arctic fibre optic cable

Sensing whales, storms, ships and earthquakes using an Arctic fibre optic cable

Simultaneous tracking of multiple whales using two fiber-optic cables in the Arctic

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