25 results on '"Barrière, Julien"'
Search Results
2. Local Infrasound Monitoring of Lava Eruptions at Nyiragongo Volcano (D.R. Congo) Using Urban and Near‐Source Stations
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Barrière, Julien, primary, Oth, Adrien, additional, d’Oreye, Nicolas, additional, Subira, Josué, additional, Smittarello, Delphine, additional, Brenot, Hugues, additional, Theys, Nicolas, additional, and Smets, Benoît, additional
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- 2023
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3. Detecting sources of shallow tremor at neighboring volcanoes in the Virunga Volcanic Province using seismic amplitude ratio analysis (SARA)
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Subirats, Jessica, Barrière, Julien, Caudron, Corentin, Hubert-Ferrari, Aurélia, Oth, Adrien, Smets, Benoit, d’Oreye, Nicolas, Kervyn, François, Subirats, Jessica, Barrière, Julien, Caudron, Corentin, Hubert-Ferrari, Aurélia, Oth, Adrien, Smets, Benoit, d’Oreye, Nicolas, and Kervyn, François
- Abstract
Volcano monitoring requires simple techniques to rapidly identify the cause of volcanic unrest. The so-called RSAM (real-time seismic amplitude measurements) technique, used in many observatories, is a good example of extracting information from seismograms with minimal processing. Built on a similar principle, the more recent seismic amplitude ratio analysis (SARA) technique allows locating migrating seismicity at high frequency (> 2 Hz, e.g. due to dike intrusions) under certain assumptions. However, such analysis generally requires a dense distribution of stations close to the seismic sources (depending on the magnitude) and/or station sites undisturbed by human activity. In a more straightforward and qualitative approach, computing amplitude ratios between station pairs can also allow for the detection of temporal and (2D) spatial changes of volcanic activity. In this work, we adopt such a simplified approach of SARA in order to characterize seismic tremors originating from two open-vent neighboring volcanoes, Nyiragongo and Nyamulagira, in the Virunga Volcanic Province (VVP) in the Democratic Republic of the Congo (DRC). In contrast with previous studies, we focus here on the low-frequency band (0.3–1 Hz), free from anthropogenic noise and sensitive to shallow volcanic tremors linked to intermittent or permanent intra-crater eruptive activity recorded through the large-aperture local network. We apply for the first time the SARA methodology for volcanic sources predominantly generating surface waves and propagating over long distances. The analysis is performed on more than two years of continuous seismic data. Seismic amplitude analysis in this frequency band is strongly influenced by the short-period microseisms originating from nearby Lake Kivu. Despite this diurnal to seasonal amplitude variability, SARA successfully detects continuous volcanic tremor activity and its arrest at both volcanoes. In light of these findings, we discuss the applicability of the, SCOPUS: ar.j, info:eu-repo/semantics/published
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- 2023
4. Listen to the sound of moving sediment in a small gravel-bed river
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Krein, Andreas, Schenkluhn, Reimar, Kurtenbach, Andreas, Bierl, Reinhard, and Barrière, Julien
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- 2016
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5. Infrasonic noise from lava eruptions at Nyiragongo volcano, D.R. Congo
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Barrière, Julien, Oth, Adrien, Subira, Josué, Smets, Benoît, and d'Oreye, Nicolas
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During eruptions, volcanoes produce air-pressure waves inaudible for the human ear called infrasound, which are very helpful for detecting early signs of magma at the surface. Compared to violent ash-rich explosions, recording more discreet atmospheric disturbances from effusive eruptions remains a practical challenge. Wind and human activity are other powerful sources of unwanted infrasound noise masking volcanic ones. At Nyiragongo volcano (D.R. Congo), close to a one-million urban area, the drainage of the world’s largest lava lake concomitant with short-duration lava flows on its flank and the renewal of an effusive eruption within its crater a few months later were a series of major volcanic events in 2021, all monitored with infrasound sensors. First, we explore these records for characterizing the temporal and spatial evolution of the flank eruption on May 22, 2021. In a second step, we show evidence of the infrasonic rumbling of a nascent lava lake starting a few months later detected up to the volcano observatory facilities in Goma city center about 17 km from Nyiragongo’s crater. These results show remarkable local recordings of eruptive infrasound from rural and city-based stations and have significant implication for optimizing future monitoring efforts in a harsh field environment., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)
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- 2023
6. Precursor-free eruption triggered by edifice rupture at Nyiragongo volcano
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Smittarello, Delphine, Smets, Benoit, Barrière, Julien, Michellier, Caroline, Oth, Adrien, Shreve, Tara, Grandin, Raphaël, Theys, Nicolas, Brenot, Hugues, Cayol, Valérie, Allard, Patrick, Caudron, Corentin, Chevrel, Oryaëlle, Darchambeau, François, de Buyl, Pierre, Delhaye, Louise, Derauw, Dominique, Ganci, Gaetana, Geirsson, Halldór, Kamate Kaleghetso, Ephrem, Kambale Makundi, J., Kambale Nguomoja, I., Kasereka Mahinda, C., Kervyn, Matthieu, Kimanuka Ruriho, C., Le Mével, Hélène, Molendijk, Sander, Namur, Olivier, Poppe, Sam, Schmid, Martin, Subira, Josué Muhindo J., Wauthier, Christelle, Yalire, Mathieu Mapendano M., d’Oreye, N., Kervyn, Francois, Syavulisembo Muhindo, A., Smittarello, Delphine, Smets, Benoit, Barrière, Julien, Michellier, Caroline, Oth, Adrien, Shreve, Tara, Grandin, Raphaël, Theys, Nicolas, Brenot, Hugues, Cayol, Valérie, Allard, Patrick, Caudron, Corentin, Chevrel, Oryaëlle, Darchambeau, François, de Buyl, Pierre, Delhaye, Louise, Derauw, Dominique, Ganci, Gaetana, Geirsson, Halldór, Kamate Kaleghetso, Ephrem, Kambale Makundi, J., Kambale Nguomoja, I., Kasereka Mahinda, C., Kervyn, Matthieu, Kimanuka Ruriho, C., Le Mével, Hélène, Molendijk, Sander, Namur, Olivier, Poppe, Sam, Schmid, Martin, Subira, Josué Muhindo J., Wauthier, Christelle, Yalire, Mathieu Mapendano M., d’Oreye, N., Kervyn, Francois, and Syavulisembo Muhindo, A.
- Abstract
Classical mechanisms of volcanic eruptions mostly involve pressure buildup and magma ascent towards the surface1. Such processes produce geophysical and geochemical signals that may be detected and interpreted as eruption precursors1–3. On 22 May 2021, Mount Nyiragongo (Democratic Republic of the Congo), an open-vent volcano with a persistent lava lake perched within its summit crater, shook up this interpretation by producing an approximately six-hour-long flank eruption without apparent precursors, followed—rather than preceded—by lateral magma motion into the crust. Here we show that this reversed sequence was most likely initiated by a rupture of the edifice, producing deadly lava flows and triggering a voluminous 25-km-long dyke intrusion. The dyke propagated southwards at very shallow depth (less than 500 m) underneath the cities of Goma (Democratic Republic of the Congo) and Gisenyi (Rwanda), as well as Lake Kivu. This volcanic crisis raises new questions about the mechanisms controlling such eruptions and the possibility of facing substantially more hazardous events, such as effusions within densely urbanized areas, phreato-magmatism or a limnic eruption from the gas-rich Lake Kivu. It also more generally highlights the challenges faced with open-vent volcanoes for monitoring, early detection and risk management when a significant volume of magma is stored close to the surface., SCOPUS: ar.j, info:eu-repo/semantics/published
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- 2022
7. Imaging the uppermost layers of the Eifel volcanic system (Germany) using ambient microseismic noise
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Barrière, Julien, primary and Oth, Adrien, additional
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- 2022
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8. Structural failure and shallow dike intrusion at Nyiragongo volcano (D.R Congo)
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Smittarello, Delphine, primary, Barrière, Julien, additional, d'Oreye, Nicolas, additional, Smets, Benoit, additional, Oth, Adrien, additional, Michellier, Caroline, additional, Shreve, Tara, additional, Grandin, Raphael, additional, Cayol, Valérie, additional, Wauthier, Christelle, additional, Derauw, Dominique, additional, Geirsson, Halldor, additional, Theys, Nicolas, additional, Brenot, Hugues, additional, Froger, Jean-Luc, additional, Muhindo, Adalbert, additional, and Kervyn, François, additional
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- 2022
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9. Propagation and arrest of the May 2021 lateral dike intrusion at Nyiragongo (D.R. Congo)
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Smittarello, Delphine, primary, Barrière, Julien, additional, d'Oreye, Nicolas, additional, Smets, Benoit, additional, Oth, Adrien, additional, Shreve, Tara, additional, Subira, Josue, additional, Mafuko Nyandwi, Blaise, additional, Cayol, Valerie, additional, Grandin, Raphael, additional, Wauthier, Christelle, additional, Derauw, Dominique, additional, Geirsson, Halldor, additional, Theys, Nicolas, additional, Darchambeau, François, additional, Poppe, Sam, additional, Allard, Patrick, additional, Caudron, Corentin, additional, Lesage, Philippe, additional, Samsonov, Sergey, additional, Delhaye, Louise, additional, Chevrel, Magdalena Oryaëlle, additional, Mashagiro, Niche, additional, Muhindo Syavulisembo, Adalbert, additional, and Kervyn, Francois, additional
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- 2021
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10. An advanced signal processing technique for deriving grain size information of bedload transport from impact plate vibration measurements
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Barrière, Julien, Krein, Andreas, Oth, Adrien, and Schenkluhn, Reimar
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- 2015
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11. Intra‐Crater Eruption Dynamics at Nyiragongo (D.R. Congo), 2002–2021.
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Barrière, Julien, Nicolas d'Oreye, Smets, Benoît, Oth, Adrien, Delhaye, Louise, Subira, Josué, Mashagiro, Niche, Derauw, Dominique, Smittarello, Delphine, Syavulisembo, Adalbert Muhindo, and Kervyn, François
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CRATER lakes , *LAVA flows , *URBAN lakes , *REMOTE-sensing images , *IMAGE reconstruction - Abstract
Nyiragongo is one of the rare volcanoes on Earth hosting a lava lake. However, the understanding of its plumbing and lava lake systems remains limited, with, until recently, only sporadic or time‐limited historical observations and measurements. Combining dense accurate lava lake and crater floor level measurements based on 1,703 satellite radar images and topographic reconstructions using photogrammetry, we obtain the first reliable picture and time evolution of intra‐crater erupted lava volumes between the two last flank eruptions in January 2002 and May 2021. The filling of the crater by lava, initiated in 2002 and continued up to May 2021, is seen as an evidence of a long‐term pressure build up of the magmatic system. This filling occurs through irregular pulsatory episodes of rising lava lake level, some of which overflow and solidify on the surrounding crater floor. Pauses of stable molten lava lake level and sudden numerous level drops also marked the summit's eruptive activity. The joint analysis with seismic records available since 2015 revealed that the largest lava lake drops are synchronous with seismic swarms associated with deep magma intrusions, generally preceded by an increase of extrusion rate within the crater. The appearance of a spatter cone in the summit crater in 2016, most likely superficially branched to the lava lake, was a clear marker of the change in eruption dynamics. This first long‐term time series of Nyiragongo's crater topography between two hazardous flank eruptions might further help to better decipher Nyiragongo's past and future behavior using multi‐parameter observations. Plain Language Summary: Nyiragongo volcano, in D.R. Congo, stands close to a densely populated area (∼1 million inhabitants). Its Hawaiian‐style eruptive activity essentially consists in a long‐lived molten lava lake or lava fountains in the summit crater lasting for weeks to decades, interrupted by effusive flank eruptions. Nyiragongo erupted on its southern flank in January 2002 and May 2021, draining the lava lake system and opening fissures producing rapid lava flows toward the city of Goma and Lake Kivu. Between these two flank eruptions, the continuous summit eruptive activity took the form of a persistent lava lake progressively filling in the summit crater. Here, we derive accurate elevation measurements of Nyiragongo's crater floor and lava lake surface between the two last flank eruptions from radar satellite instruments and 3D photogrammetric reconstruction. The lava lake, of which the level fluctuates, acts as a growing piezometer connected to the magmatic system as its rim rose by ∼300 m in about 19 years due to overflowing. A combined analysis with seismic records provides important indications on the origins of the observed variations and helps to better understand the link between the continuous eruptive activity and the deeper magmatic processes. Key Points: Processing of 1,703 satellite radar images leads to the first reliable picture of erupted volumes within Nyiragongo's crater since 2002We provide a multi‐instrumental analysis with topographic reconstructions using photogrammetry and seismic observations at NyiragongoOur approach helps to decipher the origins of surface (intra‐crater) evidences of magmatic pressure variations in the plumbing system [ABSTRACT FROM AUTHOR]
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- 2022
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12. Seismicity and outgassing dynamics of Nyiragongo volcano
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Barrière, Julien, primary, d'Oreye, Nicolas, additional, Oth, Adrien, additional, Theys, Nicolas, additional, Mashagiro, Niche, additional, Subira, Josué, additional, Kervyn, François, additional, and Smets, Benoît, additional
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- 2019
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13. Single-Station Seismo-Acoustic Monitoring of Nyiragongo's Lava Lake Activity (D.R. Congo)
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Barrière, Julien, primary, d'Oreye, Nicolas, additional, Oth, Adrien, additional, Geirsson, Halldor, additional, Mashagiro, Niche, additional, Johnson, Jeffrey B., additional, Smets, Benoît, additional, Samsonov, Sergey, additional, and Kervyn, François, additional
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- 2018
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14. Long‐term monitoring of long‐period seismicity and space‐based SO 2 observations at African lava lake volcanoes Nyiragongo and Nyamulagira (DR Congo)
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Barrière, Julien, primary, Oth, Adrien, additional, Theys, Nicolas, additional, d'Oreye, Nicolas, additional, and Kervyn, François, additional
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- 2017
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15. KivuSNet: The First Dense Broadband Seismic Network for the Kivu Rift Region (Western Branch of East African Rift)
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Oth, Adrien, primary, Barrière, Julien, additional, d’Oreye, Nicolas, additional, Mavonga, Georges, additional, Subira, Josue, additional, Mashagiro, Niche, additional, Kadufu, Benjamin, additional, Fiama, Silvanos, additional, Celli, Gilles, additional, Bigirande, Jean de Dieu, additional, Ntenge, Alain Joseph, additional, Habonimana, Laurent, additional, Bakundukize, Charles, additional, and Kervyn, François, additional
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- 2016
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16. Effect of water saturation on seismoelectric coupling : A laboratory study
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Bordes, Clarisse, Sénéchal, Pascale, Barrière, Julien, Brito, Daniel, Normandin, Eric, Jougnot, Damien, Laboratoire des Fluides Complexes et leurs Réservoirs (LFCR), Centre National de la Recherche Scientifique (CNRS)-Université de Pau et des Pays de l'Adour (UPPA)-TOTAL FINA ELF, Plateau Innov'Adour., Université de Pau et des Pays de l'Adour (UPPA), Milieux Environnementaux, Transferts et Interactions dans les hydrosystèmes et les Sols (METIS), Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Pierre et Marie Curie - Paris 6 (UPMC), ANR-08-BLAN-0251,TRANSEK,Seismo-electromagnetic conversions in porous media(2008), TOTAL FINA ELF-Université de Pau et des Pays de l'Adour (UPPA)-Centre National de la Recherche Scientifique (CNRS), Institut des sciences analytiques et de physico-chimie pour l'environnement et les materiaux (IPREM), Université de Pau et des Pays de l'Adour (UPPA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Université Pierre et Marie Curie - Paris 6 (UPMC)-École Pratique des Hautes Études (EPHE), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)
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[SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph] ,Physics::Geophysics - Abstract
International audience; Seismic waves propagating in a porous medium, under favorable conditions , generate measurable electromagnetic fields due to electrokinetic effects. It has been proposed, following experimental and numerical studies , that these so-called ?seismoelectromagnetic ? couplings depend on pore fluid properties. The theoretical frame describing these phenomena are based on the original Biot's theory, assuming that pores are fluid-filled. We study here the impact of a partially saturated medium on amplitudes of those seismoelectric couplings by comparing experimental data to an effective fluid model. We have built a 1 m-length-scale experiment designed for imbibition and drainage of an homogeneous silica sand ; the experimental setup includes a seismic source, acce-lerometers, electric dipoles and capacitance probes in order to monitor the seismic and seismoelectric fields during water saturation. Apparent velocities and frequency spectra are derived from seismic and electric measurements during experiments in varying saturation conditions. Amplitudes of the seismic and seismoelectric waves and their ratios (i.e. transfer functions) are discussed using a spectral analysis performed by Continuous Wavelet Transform (CWT). The experiment results reveal that the amplitude ratiosof seismic to co-seismic electric signals remain rather constant as a function of the water saturation. This result show good agreement with theoretically predicted transfer functions including effective fluid properties and some recent electrokinetic models. This experiment also show the evidence of the dynamic effect in seis-moelectric coupling.
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- 2014
17. On the potential of fluvial seismology and acoustic for bedload transport monitoring in small gravel-bed rivers
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Barrière, Julien, Oth, Adrien, and Krein, Andreas
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- 2014
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18. Laboratory monitoring of P-waves in partially saturated sand
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Barrière, Julien, Bordes, Clarisse, Brito, Daniel, Sénéchal, Pascale, Perroud, Hervé, Laboratoire des Fluides Complexes et leurs Réservoirs (LFCR), TOTAL FINA ELF-Université de Pau et des Pays de l'Adour (UPPA)-Centre National de la Recherche Scientifique (CNRS), Géosciences Montpellier, Université des Antilles et de la Guyane (UAG)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), and Centre National de la Recherche Scientifique (CNRS)-Université de Pau et des Pays de l'Adour (UPPA)-TOTAL FINA ELF
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Seismic attenuation ,Wave propagation ,[SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph] ,[SDE.MCG]Environmental Sciences/Global Changes ,Wavelet transform ,[PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph] ,Physics::Geophysics - Abstract
International audience; Energy dissipation is observed on seismic data when a wave propagates through a porous medium, involving different frequency regimes depending on the nature of rock and fluid types. We focus here on the role of partial fluid saturation in unconsolidated porous media, looking in particular at P-wave phase velocity and attenuation. The study consists in running an experiment in a sand-filled tank partially saturated with water. Seismic propagation in the tank is generated in the kHz range by hitting a steel ball on a granite plate. Seismic data are recorded by buried accelerometers and injecting or extracting water controls the partial saturation. Several imbibition/drainage cycles were performed between the water and gas residual saturations. A Continuous Wavelet Transform applied on seismic records allowed us to extract the direct P-wave at each receiver.We observe an hysteresis in phase velocities and inverse quality factors between imbibition and drainage. Phase velocities and inverse quality factors are then jointly inverted to get a final poro-visco-elastic model of the partially saturated sand that satisfactorily reproduces the data. The model formulation consists in generalizing the Biot theory to effective properties of the fluid and medium (permeability and bulk modulus) in order to properly explain the phase velocity variation as a function of the saturation. The strong level of attenuation measured experimentally is further explained by an anelastic effect due to grain to grain sliding, adding to Biot's losses. This study shows that fluid distribution at microscopic scale has strong influence on the attenuation of direct P-waves at macroscopic scale and confirms that seismic prospection may be a powerful tool for the characterization of transport phenomena in porous media.
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- 2012
19. Atténuation et dispersion des ondes P en milieu poreux partiellement saturé: approche expérimentale
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Barrière, Julien, Laboratoire des Fluides Complexes et leurs Réservoirs (LFCR), TOTAL FINA ELF-Université de Pau et des Pays de l'Adour (UPPA)-Centre National de la Recherche Scientifique (CNRS), Université de Pau et des Pays de l'Adour, Hervé PERROUD(herve.perroud@univ-pau.fr), and ANR TRANSEK
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Hydrogeophysics ,Ondes sismiques ,Geophysics ,[SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph] ,Milieux poreux ,Porous media ,Hydrogéophysique ,[PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph] ,Géophysique ,Seismic wave - Abstract
In order to analyse the role of partial saturation on direct P-waves phase velocity and attenuation, we performed a laboratory experiment in the kiloHertz range to avoid scale effects between field studies and traditional ultrasonic laboratory measurements. This experiment consists in a sand-filled tank equiped with accelerometers and water capacitance probes, were seismic propagation is generated by hitting a steel ball on a granite plate. Several imbibition/drainage cycles were performed between the water and gas residual saturations. Seismic data were processed by a Continuous Wavelet Transform using the complex Morlet wavelet which was numerically validated using a viscoelastic 2D code for wave propagation (Specfem2D). Phase velocity of direct P-wave decreases with the increase of water content, which is quite consistent with Biot-Gassmann-Wood (BGW) limit of the Biot's theory for both imbibition and drainage. This behaviour indicates that the fluid mixture (gaz and water) can be considered as an effective fluid, which is typical of field seismic applications. In this experiment, attenuation is very strong and cannot be fully explained by the macroscopic fluid flow of Biot's theory. It is necessary to introduce a viscoelastic contribution linked to the grain to grain overall losses, which are described by a constant Q-model. Moreover, hysteresis between imbibition and drainage are observed and explained by introducing an effective permeability of the mixture depending on water and gas relative permeabilities.; Afin d'analyser le rôle de la saturation partielle sur la vitesse de phase et l'atténuation des ondes P directes, nous avons élaboré une expérience en laboratoire dans la gamme du kiloHertz. Celle-ci permet une corrélation avec les mesures de terrain et limite les effets d'échelle induits par l'utilisation des traditionnelles mesures ultrasoniques. Le montage expérimental est composé d'un container rempli de sable, équipé d'accéléromètres et de sondes de teneur en eau. Une propagation d'onde est générée par une source mécanique constituée d'une bille en métal frappant une plaque de granite. Plusieurs cycles d'imbibition/drainage sont réalisés entre les saturations résiduelles en eau et en air. Une transformée continue en ondelette a été choisie pour le traitement des données sismiques et validée numériquement par une simulation de propagation d'ondes dans un milieu viscoélastique 2D (code Specfem2D). En imbibition et en drainage, la vitesse de phase décroît avec l'augmentation de la saturation, ce qui peut être expliqué par la limite Biot-Gassmann-Wood (BGW) de la théorie de Biot. Ce comportement, typique des mesures de terrain, indique qu'il est possible de considérer le mélange de fluides (eau et air) comme un fluide effectif. L'interprétation de l'atténuation est plus complexe et ne peut être expliquée par le mécanisme de relaxation de flux macroscopique de la théorie de Biot. Il est nécessaire d'introduire une contribution viscoélastique reliée aux pertes frictionelles grain-à-grain et décrite par un modèle à Q constant. De plus, un hystérésis entre imbibition et drainage est observé et expliqué en introduisant une perméabilité effective du mélange, dépendante des perméabilités relatives à l'eau et à l'air.
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- 2011
20. Bed load transport monitoring using seismic observations in a low-gradient rural gravel bed stream
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Barrière, Julien, primary, Oth, Adrien, additional, Hostache, Renaud, additional, and Krein, Andreas, additional
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- 2015
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21. Long-term monitoring of long-period seismicity and space-based SO2 observations at African lava lake volcanoes Nyiragongo and Nyamulagira (DR Congo).
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Barrière, Julien, Oth, Adrien, Theys, Nicolas, d'Oreye, Nicolas, and Kervyn, François
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- 2017
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22. Long‐term monitoring of long‐period seismicity and space‐based SO2observations at African lava lake volcanoes Nyiragongo and Nyamulagira (DR Congo)
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Barrière, Julien, Oth, Adrien, Theys, Nicolas, d'Oreye, Nicolas, and Kervyn, François
- Abstract
Magma ascent that may lead to an eruption is commonly accompanied by variations of long‐period seismic activity and SO2degassing. Space‐based measurements of SO2emission rates represent a rapidly emerging and highly convenient approach for volcano monitoring; however, combining these long‐term remote sensing observations with seismic data is still rare and, in particular, the potential of such a multidisciplinary approach as volcano monitoring tool remains largely unexplored. Here shallow magmatic activity and magma migration patterns at the two closely located African volcanoes Nyiragongo and Nyamulagira are inferred from a nearly 3 years long SO2emissions record and seismic observations between April 2014 and February 2017. The discrimination of magma movements into shallow plumbing systems allows for signs of volcanic unrest to be deciphered on a daily time scale, even with limited instrumentation on site. Multidisciplinary monitoring framework using seismic data and space‐based SO2measurements at African lava lake volcanoesCharacterization of the spatiotemporal shallow magmatic activity and magma migration patterns during nearly 3 yearsNew insights into the dynamics of two of the most active African volcanoes (Nyiragongo and Nyamulagira)
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- 2017
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23. Pressures changes in volcanic systems and volcanic interactions in the Virunga Volcanic Province inferred from lava lake level measurements.
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d'Oreye, Nicolas, Barrière, Julien, Derauw, Dominique, Gheirsson, Halldor, Smets, Benoît, Oth, Adrien, Samsonov, Sergey, and Kervyn, François
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VOLCANIC eruptions , *LAVA , *LAKES , *LAVA flows , *VOLCANOES - Abstract
Lava lakes are the uppermost parts of magmatic systems and changes in the height of those lakes provide insight into pressure changes in the magmatic systems. We measure the rise of the crater floor and the lava lake level fluctuations from the module of hundreds of SAR images acquired by RADARSAT, COSMO-SkyMed, SENTIEL-1 and Envisat. The height changes are obtained from the length of the shadow casted by surrounding rims. We develop an automatic method for detecting illumination/shadow transitions using a grid-search strategy among an extensive dictionary of synthetics 1-D transects. Results are validated by comparison with high resolution DEMs obtained from UAV photogrammetry. This analysis is applied to the Nyiragongo volcano (DR Congo), which hosts a ~260m wide persistent lava lake nested in a 1.2km wide crater. Recurrent lava overflows inundate the crater, which, after solidification, make the floor to rise up to several dozens of meters per year. After its co-eruptive drainage in 2002, the crater filled up to ~400m thickness until 2008. From 2008 to 2012, the variations in lava lake level reduced (level fluctuations of various amplitude and time scales within the pit). In 2012, after a large volume eruption at neighboring Nyamulagira volcano, the level progressively lowered, reaching ~70m below the crater floor. It remained at low level until the end of 2015. Early in 2016 a new vent opened within the crater, which intermittently emits important lava flows that blanket the crater. In November 2016, the lake level dropped of a hundred meters in a few hours. Since then, the lava lake level experienced several large amplitude drops. We compare these measures with other observations, such as seismicity, degassing, ground deformation and visual observations. We infer that these lava lake level changes can be used as a proxy for the pressure changes in the magmatic system. In addition, petrological studies show that despite a distance as small as 13km, Nyiragongo and neighboring Nyamulagira volcanoes share no common magmatic sources, at least at crustal depth. Nevertheless, comparing volcanic activity at both volcanoes, seismicity, regional ground deformation and lava lake level changes, our study suggests that volcanic activity at one volcano can influence the other volcano. The SAR shadow measurement method can be applied to some of the other rare volcanoes hosting or having hosted a lava lake, such as Kīlauea or Erta Ale. [ABSTRACT FROM AUTHOR]
- Published
- 2019
24. Investigation of cyclic relation between Nyiragongo SO2 fluxes and its lava lake height.
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Hugues, Brenot, Theys, Nicolas, Van Roozendael, Michel, Fayt, Caroline, Gliß, Jonas, Stebel, Kerstin, Smets, Benoît, Barrière, Julien, d'Oreye, Nicolas, Mapendano, Mathieu Yalire, Minani, Abel, Syauswa, Muhindo, Arellano, Santiago, and Kervyn, François
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- 2019
25. The broadband seismic network KivuSNet in the Virunga Volcanic Province (Democratic Republic of the Congo): seismicity catalogues and fundamental seismological models after more than 2 years of continuous operation.
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Oth, Adrien, Kervyn, François, Mavonga, Georges, Barrière, Julien, and d'Oreye, Nicolas
- Published
- 2018
Catalog
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