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• Turquet, Antoine Leo; Wüstefeld, Andreas; Baird, Alan F.; Iranpour, Kamran; Dichiarante, Anna Maria & Stokkan, Sindre [Show all 11 contributors for this article] (2026). NORFOX: An Experimental Fibre-Optic DAS Array for Seismo-Acoustic Monitoring in Norway. Pure and Applied Geophysics (PAGEOPH). ISSN 0033-4553. doi: 10.1007/s00024-026-04076-y. Full text in Research Archive Show summary

  Distributed Acoustic Sensing (DAS) is a rapidly developing technology providing spatially dense data of great value for seismic and acoustic monitoring. This paper presents NORFOX, a dedicated DAS installation in southeastern Norway. NORFOX comprises a dedicated fibre-optic array with a geometry designed for earthquake and explosion monitoring. A defining feature of the site is its co-location with the NORES seismic and infrasound arrays, enabling direct comparison of DAS observations with conventional seismic and acoustic measurements. This multi-sensor configuration provides a controlled environment for benchmarking DAS data, and it paves the way for advanced, multi-physics wavefield modelling. NORFOX records various natural and anthropogenic seismo-acoustic signals, including earthquakes, explosions, aircraft, and thunder. The ultra-dense spatial sampling provided by DAS can complement traditional monitoring networks, including those used for nuclear-test monitoring. NORFOX helps address key challenges in small-yield event detection, phase discrimination, and event classification. We describe the DAS array layout, the design rationale, the co-located instrumentation, and provide an initial characterisation of fibre performance and background noise behaviour. We also discuss practical aspects of operating the site and outline current limitations. The site is further complemented by an all-sky camera and weather station to record visual events such as meteoroids and lightning activity, and to measure environmental changes; both of which can support the interpretation of the DAS measurements. Using representative examples, we demonstrate the capability of NORFOX for DAS-based array analysis and benchmarking against conventional arrays. NORFOX therefore provides a valuable test-bed for developing, validating and comparing future DAS monitoring approaches in seismology and seismo-acoustic sensing.

• Hibert, Clément; Retailleau, Lise; Saurel, Jean-Marie; Malet, Jean-Philippe; Forestier, Germain & Weber, Jonathan [Show all 9 contributors for this article] (2025). Self-supervised learning of seismological data reveals new eruptive sequences at the Mayotte submarine volcano. Geophysical Journal International. ISSN 0956-540X. 240(1), p. 1–12. doi: 10.1093/gji/ggae361. Full text in Research Archive
• Turquet, Antoine Leo; Brissaud, Quentin; Alvizuri, Celso; Näsholm, Sven Peter; Pichon, Alexis Le & Kero, Johan (2024). Retrieving Seismic Source Characteristics Using Seismic and Infrasound Data: The 2020 M<inf>L</inf> 4.1 Kiruna Minequake, Sweden. Geophysical Research Letters. ISSN 0094-8276. 51(12), p. e2024GL109276–e2024GL109276. doi: 10.1029/2024GL109276. Full text in Research Archive Show summary

  A minequake of magnitude ML 4.1 occurred on 18 May 2020 early in the morning at the LKAB underground iron ore mine in Kiruna, Sweden. This is the largest mining-induced earthquake in Scandinavia. It generated acoustic signals observed at three infrasound arrays at 9.3 (KRIS, Sweden), 155 (IS37, Norway), and 286 km (ARCI, Norway) distance. We perform full-waveform focal mechanism inversion based on regional seismic data and local infrasound data. These independently highlight that this event was dominated by a shallow-depth collapse in agreement with in-mine seismic station data. However, regional infrasound data cannot inform the inversion process without an accurate model of atmospheric winds and temperatures. Yet, our numerical simulations demonstrate a potential of using local and regional infrasound data to constrain an event's focal mechanism and depth.

• Turquet, Antoine Leo; Wüstefeld, Andreas; Svendsen, Guro Kristin; Nyhammer, Finn Kåre; Nilsen, Espen & Per-Ola, Persson Andreas [Show all 7 contributors for this article] (2024). Automated Snow Avalanche Monitoring and Alert System Using Distributed Acoustic Sensing in Norway. GeoHazards. 5(4), p. 1326–1345. doi: 10.3390/geohazards5040063. Full text in Research Archive
• Froment, Marouchka; Brissaud, Quentin; Näsholm, Sven Peter; Solberg, Celine Marie; Kaschwich, Tina & Turquet, Antoine Leo (2024). Probing a planet from the subsurface to the atmosphere with infrasound data. INTER-NOISE and NOISE-CON Congress and Conference Proceedings. ISSN 0736-2935. 270(5), p. 6164–6175. doi: 10.3397/IN_2024_3692. Full text in Research Archive Show summary

  The analysis of infrasound waves has a significant potential for retrieving a range of geophysical parameters across various scales, such as atmospheric structures, characteristics of surface and buried sources, and seismic velocity structures. This potential was recently showcased in infrasound studies that illustrated the ability to retrieve Earth's shallow velocities and Mars' near-surface atmospheric winds from remote acoustic observations. Consequently, infrasound is becoming an essential component of planetary missions, providing insights into the interiors and atmospheres of other terrestrial planets in the solar system. However, utilizing infrasound data requires efficient forward wave simulation techniques and an accurate description of waveform sensitivity to source and medium parameters. Even under ideal conditions, many inverse problems associated with infrasound-based probing are inherently ill-posed, necessitating regularization or other approaches to ensure reliable results. In this contribution, we highlight recent seismo-acoustic research findings, addressing atmospheric probing at both smaller and global scales, as well as innovative methods to accelerate infrasonic wave propagation modeling.

• Eriksen, Fredrik Kvalheim; Moura, Marcel; Jankov, Mihailo; Turquet, Antoine Leo & Måløy, Knut Jørgen (2022). Transition from viscous fingers to compact displacement during unstable drainage in porous media. Physical Review Fluids. 7(1). doi: 10.1103/PhysRevFluids.7.013901. Full text in Research Archive Show summary

  We describe a crossover from the viscous fingering instability to a compact invasion regime during viscously unstable drainage of porous media, and we investigate the underlying mechanisms of this compact fluid displacement. The study is based on a series of drainage experiments in a radial porous Hele-Shaw cell where we systematically vary the viscosity of the defending (wetting) fluid and the overpressure of the invading (nonwetting) fluid to map out the resulting invasion structures as a function of viscosity ratio and injection pressure. We show that above a threshold of injection pressure and viscosity ratio a more stable and compact invasion structure emerges within the viscous fingering patterns, i.e., a roughly circular displacement with viscous fingers on the outside. The onset of the stable displacement is found to begin at a rather low viscosity ratio M between the invading and defending fluids, i.e., when M≥10−3 for injection pressures of 3–5 kPa. We find that the ratio between the length of the outer fingers and the size of the compact invasion scales with the viscosity ratio and approaches a more or less constant value during growth, resulting in structures with proportionate growth and larger compact invasions for higher viscosity ratios. As opposed to the viscous fingering instability, we describe rich ganglion dynamics within the compact invasion structures and show that the pressure gradient is not screened by the outer fingers.

• Turquet, Antoine Leo; Toussaint, Renaud; Eriksen, Fredrik Kvalheim; Daniel, Guillaume; Lengline, Oliver & Flekkøy, Eirik Grude [Show all 7 contributors for this article] (2019). Source localization of microseismic emissions during pneumatic fracturing. Geophysical Research Letters. ISSN 0094-8276. 46(7), p. 3726–3733. doi: 10.1029/2019GL082198. Full text in Research Archive Show summary

  Localization of signals is a widely applied technique used in different areas of science telecommunication, medicine, or seismology. In this work, we study microseismic emissions due to stick‐slip events during pneumatic fracture in a transparent setup at laboratory scale and apply a localization method “Estimated Source Energy Homogeneity.” The seismic location results are compared with the image correlation results for displacement maps corresponding to the event times. We have observed (using optics and acoustics) that the movement starts inside the porous medium and progresses toward the channel tips, eventually causing channels to grow further. This finding could be of interest in understanding fluid‐induced earthquake nucleation processes. Similar to in‐site applications of pneumatic or fluid‐related fracturing, it shows that the area influenced extends beyond the fracture tips. This also shows why even after the end of pumping, we may get earthquakes, such as in the Basel case (Haring et al., 2008, https://doi.org/10.1016/j.geothermics.2008.06.002).

• Turquet, Antoine Leo; Bodin, Thomas; Arroucau, Pierre; Sylvander, Matthieu & Manchuel, Kevin (2019). Quantifying the seismic location uncertainties in French Seismicity Catalogues: Application to the Pyrenees. Journal of Seismology. ISSN 1383-4649. doi: 10.1007/s10950-019-09857-8. Full text in Research Archive

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• Turquet, Antoine Léo; Svendsen, Guro Kristin; Wüstefeld, Andreas; Nyhammar, F.K.; Persson, A.P.O. & Refsum, Vetle Kind (2025). Next-Generation Real Time Avalanche Monitoring: Distributed Acoustic Sensing for Multi-Site Integration and Advanced Environmental Noise Analysis. Full text in Research Archive
• Moura, Marcel; Eriksen, Fredrik Kvalheim; Jankov, Mihailo; Turquet, Antoine Leo; Hansen, Alex & Måløy, Knut Jørgen (2024). Experiments on transient and steady-state flows in porous media: the transition from viscous fingers to compact displacement during unstable drainage flows. Full text in Research Archive
• DonnaDille, Mathieu; Turquet, Antoine Leo; Hibert, Clément & Richard, Cedric (2024). Distributed Acoustic Sensing automated classifiers design via transfer learning for seismology. Full text in Research Archive Show summary

  We built a small test dataset of 543 signals using 20 channels equally distributed along the DAS array. Several transfer learning approaches were also explored and discussed. Results highlight the potential of a transfer learning approach to build new DAS classifiers. By leveraging historical seismometer catalogs, this approach facilitates the creation of DAS classifiers, thereby saving substantial time and avoiding the need for creating specialized datasets exclusively for DAS. Several strategies for improving score thresholds for future classifiers based on these transfer learning methods can be derived.

• Turquet, Antoine Leo; Wüstefeld, Andreas; Nyhammer, Finn Kåre; Nilsen, Espen & Refsum, Vetle Kind (2024). Advances in Avalanche Monitoring in Norway: Insights from Distributed Acoustic Sensing. Full text in Research Archive Show summary

  In this project, the focus of the installation is to detect avalanches that hit the road and determine whether any vehicles were trapped under the avalanches. For the winter season of 2022-2023 eight avalanches hit the road. The DAS-based monitoring system managed to successfully detect and classify these avalanches.

• Turquet, Antoine Leo; Wüstefeld, Andreas; Svendsen, Guro Kristin; Nyhammer, Finn Kåre; Nilsen, Espen & Refsum, Vetle Kind (2024). AUTOMATED AVALANCHE MONITORING, DETECTION AND CLASSIFICATION SYSTEM POWERED BY DISTRIBUTED ACOUSTIC SENSING. Full text in Research Archive Show summary

  In this project, the focus of the installation is to detect avalanches that hit the road and determine whether any vehicles were trapped under the avalanches. For the winter season of 2022-2023 eight avalanches hit the road. The DAS-based monitoring system managed to successfully detect and classify these avalanches.

• Näsholm, Sven Peter; Amezcua, Javier; Assink, Jelle D.; Belova, Evgenia; Blixt, Mårten & Brissaud, Quentin [Show all 16 contributors for this article] (2023). Summarizing the research of the MADEIRA project - Middle atmosphere dynamics: exploiting infrasound using a multidisciplinary approach at high latitudes. Full text in Research Archive
• Moura, Marcel; Eriksen, Fredrik Kvalheim; Jankov, Mihailo; Turquet, Antoine Leo & Måløy, Knut Jørgen (2022). Transition from viscous Fingers to compact displacement during unstable drainage in porous media. Full text in Research Archive
• Brissaud, Quentin; Näsholm, Sven Peter & Turquet, Antoine Leo (2021). Predicting infrasound transmission loss using deep learning. Full text in Research Archive Show summary

  Modeling the spatial distribution of infrasound attenuation (or transmission loss, TL) from surface sources is key to understanding and interpreting observations at ground-based stations. Such predictions enable the reliable assessment of infrasound source characteristics such as ground pressure levels associated with earthquakes, volcanic explosion properties, yield of nuclear and non-nuclear explosions, and ocean-generated microbaroms wavefields. However, the computational cost associated with current full-waveform modeling tools, such as Parabolic Equation (PE) codes, often prevents the exploration of a large parameter space, i.e., variations in wind models, source frequency, and source location, when deriving reliable estimates of source or atmospheric properties — in particular for real-time and near-real-time applications. Therefore, many studies rely on analytical regression heuristic TL equations that neglect complex vertical wind variations and the range-dependent variation in the atmospheric properties. This introduces significant uncertainties in the predicted TL. In this contribution, we propose a deep-learning model trained on a large set of simulated wavefields using PE simulations and ERA5 re-analysis atmospheric models to predict infrasound amplitudes up to 1000 km from the source, also accounting for arbitrarily large vertical and horizontal wind variations. Given an atmospheric model, our new modeling framework provides a fast (0.05 s runtime) and reliable (<5 dB error on average, compared to PE simulations) estimate of the infrasound TL. This work paves the way for real-time monitoring and characterization of infrasound sources such as active volcanoes and man-made explosions. We also see a potential for this approach to be incorporated into frameworks that invert for infrasound source locations, and into studies where infrasound datasets are exploited to constrain atmospheric and numerical weather prediction models.

• Rodriguez, Ismael Vera; Näsholm, Sven Peter; Brissaud, Quentin; Turquet, Antoine Leo & Pichon, Alexis Le (2021). Estimation of infrasound-consistent wind and temperature atmospheric profiles from model ensembles in North Scandinavia. Full text in Research Archive Show summary

  Atmospheric reanalysis models rely on the assimilation of direct and indirect measurements of different properties of the atmosphere. A better representation of the upper stratosphere in these models, especially for winds, can contribute to enhanced numerical weather predictions on weekly to monthly timescales. Thus, in the current work, we consider the problem of estimating an updated atmospheric model to become consistent with a set of infrasound array observations of travel-time, backazimuth, and apparent velocity.

• Turquet, Antoine Leo; Brissaud, Quentin; Kero, Johan; Näsholm, Sven Peter; Pichon, Alexis Le & Listowski, Constantino [Show all 7 contributors for this article] (2021). Near and Far-Field Seismo-Acoustic Analysis of Mb 4.9 Mining Induced Earthquake Nearby Kiruna, Sweden. Full text in Research Archive
• Turquet, Antoine Leo; Brissaud, Quentin; Kero, Johan; Näsholm, Sven Peter; Kværna, Tormod & Pichon, Alexis Le [Show all 7 contributors for this article] (2021). Insights from mb4.9 Kiruna Minequake (Sweden) - 18 May 2020. Full text in Research Archive
• Turquet, Antoine Leo; Brissaud, Quentin; Näsholm, Sven Peter; Kero, Johan; Kværna, Tormod & Listowski, C. [Show all 7 contributors for this article] (2021). Near and far-field seismo-acoustic analysis of mb 4.9 mining induced earthquake nearby Kiruna, Sweden. Full text in Research Archive
• Turquet, Antoine Leo; Brissaud, Quentin; Kero, Johan; Näsholm, Sven Peter; Kværna, Tormod & Pichon, Alexis Le [Show all 7 contributors for this article] (2021). Seismo-acoustic analysis of Mw 4.2 mining induced earthquake nearby Kiruna, Sweden. Full text in Research Archive
• Rodriguez, Ismael Vera; Näsholm, Sven Peter; Turquet, Antoine Leo & Evers, Läslo G. (2020). Climatology reflected by infrasound travel-times sampling the stratosphere in its transition between summer and winter. Full text in Research Archive
• Näsholm, Sven Peter; Vorobeva, Ekaterina; Pichon, Alexis Le; Orsolini, Yvan; Turquet, Antoine Leo & Hibbins, Robert [Show all 10 contributors for this article] (2020). Semidiurnal tidal signatures in microbarom infrasound array measurements. Full text in Research Archive
• Turquet, Antoine Leo; Toussaint, Renaud; Eriksen, Fredrik Kvalheim; Flekkøy, Eirik Grude & Måløy, Knut Jørgen (2020). Reverse Engineering Earthquakes using Lab-scale Replicas: Application to Mw5. 5 2017 Pohang Earthquake. Full text in Research Archive

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