Long‐term monitoring of long‐period seismicity and space‐based SO<sub>2</sub> observations at African lava lake volcanoes Nyiragongo and Nyamulagira (DR Congo)

Barrière, Julien; Oth, Adrien; Theys, Nicolas; d’Oreye, Nicolas; Kervyn, F.

doi:10.1002/2017gl073348

Cited by 16 publications

(25 citation statements)

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“…The rather low velocity values chosen for the Earth correspond to typical subsurface soft material and are in accordance with the travel-time curve obtained by Barrière et al (2017) for surface waves generated by the continuous tremor at Nyiragongo. We define a line of 12 acousticseismic receivers spaced 500 meters along the topographic profile between the summit and KBTI.…”

Section: -D Numerical Simulation Of the Seismo-acoustic Propagation supporting

confidence: 81%

“…Although no detailed event classification has yet been performed, these seismic events generally have characteristics of volcano-tectonic earthquakes (e.g., higher and broader frequency content than LP events, more clear P or S wave onsets). Volcano-tectonic locations are obtained using a "picking-free" cross-correlation based technique adapted to low SNR events (see Barrière et al, 2017) and a simple low-resolution 1-D velocity model with two layers between 0 and 30 km depth for the Virunga Volcanic Province (VVP) (Mavonga et al, 2010). Precise hypocenter determination is adversely impacted by the use of this rough velocity model and relatively poor station coverage around the volcano (see Oth et al, 2017).…”

Section: Figure 11 | (A)mentioning

confidence: 99%

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Single-Station Seismo-Acoustic Monitoring of Nyiragongo's Lava Lake Activity (D.R. Congo)

et al. 2018

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Since its last effusive eruption in 2002, Nyiragongo has been an open-vent volcano characterized by the world's largest persistent lava lake. This lava lake provides a unique opportunity to detect pressure change in the magmatic system by analyzing its level fluctuations. We demonstrate that this information is contained in the seismic and infrasound signals generated by the lava lake's activity. The continuous seismo-acoustic monitoring permits quantification of lava lake dynamics, which is analyzed retrospectively to identify periods of volcanic unrest. Synchronous, high-resolution satellite SAR (Synthetic Aperture Radar) images are used to constrain lava lake level by measuring the length of the SAR shadow cast by the rim of the pit crater where the lava lake is located. Seventy-two estimations of the lava lake level were obtained with this technique between August 2016 and November 2017. These sporadic measurements allow for a better interpretation of the continuous infrasound and seismic data recorded at the closest station (∼6 km from the crater). Jointly analyzed seismo-acoustic and SAR data reveal that slight changes in the spectral properties of the continuous cross-correlated low-frequency seismo-acoustic records (and not solely single events) can be used to track fluctuations of the lava lake level on a daily and hourly basis. We observe that drops of the lava lake and the appearance of significant long period (LP) "lava lake" events are a consequence of a probable deep lateral magma intrusion beneath Nyiragongo, which induces changes in its shallow plumbing system. In addition to contributing to understanding lava lake dynamics, this study highlights the potential to continuously monitor pressure fluctuations within the magmatic system using a single seismo-acoustic station located several kilometers from the vent.

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Section: -D Numerical Simulation Of the Seismo-acoustic Propagation supporting

confidence: 81%

Section: Figure 11 | (A)mentioning

confidence: 99%

Single-Station Seismo-Acoustic Monitoring of Nyiragongo's Lava Lake Activity (D.R. Congo)

et al. 2018

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“…As one of the most abundant gases in a volcanic plume, SO 2 is often used as a tracer for volcanic emissions by a variety of spectroscopic remote sensing techniques. The strong characteristic absorption features in the UV spectral range allow for the quantification of SO 2 using differential optical absorption spectroscopy (DOAS; see, e.g., Stutz, 2008 andWagner, 2011) both from the ground (e.g., Bobrowski and Platt, 2007;Galle et al, 2003) and from space (e.g., Eisinger and Burrows, 1998;Khokhar et al, 2005 andKrueger, 1985).…”

Section: Satellite So 2 Vertical Column Density Datamentioning

confidence: 99%

African volcanic emissions influencing atmospheric aerosols over the Amazon rain forest

et al. 2018

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Abstract. The long-range transport (LRT) of trace gases and aerosol particles plays an important role for the composition of the Amazonian rain forest atmosphere. Sulfate aerosols originate to a substantial extent from LRT sources and play an important role in the Amazonian atmosphere as strongly light-scattering particles and effective cloud condensation nuclei. The transatlantic transport of volcanic sulfur emissions from Africa has been considered as a source of particulate sulfate in the Amazon; however, direct observations have been lacking so far. This study provides observational evidence for the influence of emissions from the Nyamuragira–Nyiragongo volcanoes in Africa on Amazonian aerosol properties and atmospheric composition during September 2014. Comprehensive ground-based and airborne aerosol measurements together with satellite observations are used to investigate the volcanic event. Under the volcanic influence, hourly mean sulfate mass concentrations in the submicron size range reached up to 3.6 µg m−3 at the Amazon Tall Tower Observatory, the highest value ever reported in the Amazon region. The substantial sulfate injection increased the aerosol hygroscopicity with κ values up to 0.36, thus altering aerosol–cloud interactions over the rain forest. Airborne measurements and satellite data indicate that the transatlantic transport of volcanogenic aerosols occurred in two major volcanic plumes with a sulfate-enhanced layer between 4 and 5 km of altitude. This study demonstrates how African aerosol sources, such as volcanic sulfur emissions, can substantially affect the aerosol cycling and atmospheric processes in Amazonia.

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“…Aerosols offset the ongoing regional climate warming in SSA, shift monsoon and precipitation patterns, and are detrimental to the air quality (IPCC, 2013;WHO, 2016). Ambient air pollution in SSA is estimated to cause 563 000 premature deaths annually, making it one of the main causes of mortality in the region (Bauer et al, 2019). However, the level of scientific understanding of the overall health and climate impact of aerosols is still low, owing to the complex aerosol life cycle during which emissions, transformations, and sinks are associated with large uncertainties, in particular given their vast physical and chemical complexity.…”

Section: Introductionmentioning

confidence: 99%

Seasonal source variability of carbonaceous aerosols at the Rwanda Climate Observatory

et al. 2020

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Abstract. Sub-Saharan Africa (SSA) is a global hot spot for aerosol emissions, which affect the regional climate and air quality. In this paper, we use ground-based observations to address the large uncertainties in the source-resolved emission estimation of carbonaceous aerosols. Ambient fine fraction aerosol was collected on filters at the high-altitude (2590 m a.s.l.) Rwanda Climate Observatory (RCO), a SSA background site, during the dry and wet seasons in 2014 and 2015. The concentrations of both the carbonaceous and inorganic ion components show a strong seasonal cycle, with highly elevated concentrations during the dry season. Source marker ratios, including carbon isotopes, show that the wet and dry seasons have distinct aerosol compositions. The dry season is characterized by elevated amounts of biomass burning products, which approach ∼95 % for carbonaceous aerosols. An isotopic mass-balance estimate shows that the amount of the carbonaceous aerosol stemming from savanna fires may increase from 0.2 µg m−3 in the wet season up to 10 µg m−3 during the dry season. Based on these results, we quantitatively show that savanna fire is the key modulator of the seasonal aerosol composition variability at the RCO.

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Long‐term monitoring of long‐period seismicity and space‐based SO₂ observations at African lava lake volcanoes Nyiragongo and Nyamulagira (DR Congo)

Cited by 16 publications

References 62 publications

Single-Station Seismo-Acoustic Monitoring of Nyiragongo's Lava Lake Activity (D.R. Congo)

Single-Station Seismo-Acoustic Monitoring of Nyiragongo's Lava Lake Activity (D.R. Congo)

African volcanic emissions influencing atmospheric aerosols over the Amazon rain forest

Seasonal source variability of carbonaceous aerosols at the Rwanda Climate Observatory

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Long‐term monitoring of long‐period seismicity and space‐based SO2 observations at African lava lake volcanoes Nyiragongo and Nyamulagira (DR Congo)

Cited by 16 publications

References 62 publications

Single-Station Seismo-Acoustic Monitoring of Nyiragongo's Lava Lake Activity (D.R. Congo)

Single-Station Seismo-Acoustic Monitoring of Nyiragongo's Lava Lake Activity (D.R. Congo)

African volcanic emissions influencing atmospheric aerosols over the Amazon rain forest

Seasonal source variability of carbonaceous aerosols at the Rwanda Climate Observatory

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Product

Resources

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Long‐term monitoring of long‐period seismicity and space‐based SO₂ observations at African lava lake volcanoes Nyiragongo and Nyamulagira (DR Congo)