Understanding the relationship between the mass eruption rate (MER) and volcanic column height is essential for both real-time volcanic hazard management and reconstruction of past explosive eruptions. Using 134 eruptive events from the new Independent Volcanic Eruption Source Parameter Archive (IVESPA, v1.0), we constrain bespoke empirical MER-height relationships for four measures of column height: spreading level, sulfur dioxide height, and two measures of top height, from direct observations and as reconstructed from deposits. These relationships show significant differences, and we discuss implications for their applications in ash dispersion forecasting and modelling volcanic climate impacts. The roles of atmospheric stratification, wind, and humidity remain challenging to detect across the wide range of eruptive conditions spanned in IVESPA, ultimately resulting in empirical relationships outperforming analytical scaling relationships and the Geneva 1-dimensional (1D) volcanic plume model accounting for atmospheric conditions. However, when excluding the IVESPA events with the highest uncertainties, the 1D model progressively outperforms the empirical MER-height relationship. Our findings highlight persisting challenges in constraining the MER-height relation and reinforce the need for improved eruption source parameter databases documenting uncertainties, as well as improved physics-based models.

How to cite: Aubry, T., Engwell, S., Bonadonna, C., Mastin, L., Carazzo, G., Van Eaton, A., Jessop, D., Grainger, R., Scollo, S., Taylor, I., Jellinek, M., Schmidt, A., Biass, S., and Gouhier, M.: New insights into the relationship between mass eruption rate and volcanic column , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10163, https://doi.org/10.5194/egusphere-egu24-10163, 2024.

The expression of volcanic activity at the Earth’s surface is accompanied by the emission of a cocktail of different gases, including water, carbon dioxide, sulphur species, halogens and metals. The composition and magnitude of these emissions reflects the state of magmatic systems, providing insights into volcanic processes and key hazard monitoring information. Many of these products also have serious health implications for local communities and are important species for the global climate. The primary target species for quantification of volcanic emissions is SO₂, due to its high prevalence in volcanic emissions, its low typical atmospheric concentration and the ability to detect it remotely using UV and IR spectroscopy from both ground and space.

Satellite instruments provide a global view of volcanic activity through a combination of geostationary and polar orbiting platforms. This is particularly useful for remote or difficult to reach volcanoes, as well as for identifying eruptions from those which have not been historically active. Most previous satellite work has focused on explosive eruptions due to the decreased sensitivity of satellites to SO₂ lower in the atmosphere, however recent advances in instrumentation and processing algorithms have opened the possibility of detecting and quantifying passive emissions in the troposphere.

In this work we combine daily SO₂ imagery from the TROPOMI satellite instrument with the PlumeTraj back-trajectory analysis toolkit to detect and quantify daily eruptive and non-eruptive SO₂ emissions as a function of time and altitude from volcanoes globally throughout the year 2020. We consistently detect more than 20 degassing volcanoes per day, dominated by non-eruptive emissions. We also investigate the emissions with respect to latitude, tectonic setting and volcano type.

These results demonstrate the ability of TROPOMI and PlumeTraj to provide daily automatic SO₂ emissions for volcanoes globally. In the future, this analysis will be extended to the full TROPOMI dataset (from 2018 to present) as well as to the development of a near real-time processing workflow. This will generate an invaluable dataset of volcanic degassing for investigating volcanic processes and characterising SO₂ emissions as a function of latitude and altitude, an important input for global climate modelling. Finally, the near real-time analysis will provide a key monitoring tool for volcano observatories worldwide.

How to cite: Esse, B., Burton, M., Hayer, C., and Queißer, M.: Quantifying daily volcanic SO2 emissions on a global scale, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5975, https://doi.org/10.5194/egusphere-egu24-5975, 2024.

The April 2021 explosive eruption of La Soufrière, St Vincent, produced plumes of ash and SO₂ which were observed with multiple satellite instruments. In this project these were studied with the Advanced Baseline Imager (ABI) on the Geostationary Operational Environmental Satellite (GOES) and the Infrared Atmospheric Sounding Interferometer (IASI) onboard the three MetOp satellites.

The high temporal resolution of the ABI instrument (1-10 minutes) was used to identify the approximate start and end times of each eruptive event during the 14-day eruption. There were a minimum of 35 explosive events which have been divided into four phases. The first was an initial explosive event, which was followed by a sustained event lasting over nine hours. The eruption then entered a pulsatory phase which consisted of 25 explosive events in a 65.3 hour period. Finally, there was a waning sequence of events. Over the final two phases, the duration of each event and the repose time between them was shown to increase.

The IASI instrument has sensitivity to sulfur dioxide (SO₂) which can be exploited to flag pixels containing SO₂ and then to quantify the amount and height. Using IASI data, the SO₂ plume was tracked as it was transported around the globe between –45 and 45° N. The retrievals showed a complex structure to the plume which may reflect the multiple explosive events that occurred. Most of the SO₂ was shown to be in the upper troposphere and lower stratosphere. A peak SO₂ mass loading of 0.31 ± 0.09 Tg occurred on 13 April a few days after the eruption began. The total mass values were converted into fluxes, with the highest fluxes occurring in the first few days of the eruption. In total it is estimated that the eruption emitted 0.63 ± 0.5 Tg of SO₂.

A number of similarities between the 1979 and 2021 eruptions of La Soufrière were observed in this study. These include the sequence of events with both eruptions including a pulsatory phase and the plume heights. These similarities highlight the value of these studies for better understanding eruptive events.

How to cite: Taylor, I. A., Grainger, R. G., Prata, A. T., Proud, S. R., Mather, T. A., and Pyle, D. M.: A satellite study of the volcanic plumes produced during the April 2021 eruption of La Soufrière, St Vincent, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12580, https://doi.org/10.5194/egusphere-egu24-12580, 2024.

Explosive volcanic eruptions can damage or destroy surrounding forests, with the potential to alter their characteristics over different timescales. The damage can range from minor/temporary damage to total destruction and burial of vegetated landscapes. While eruptions resulting in vegetation damage over 100s of kilometres are rare, some volcanoes regularly impact and damage local vegetation, with frequencies of months to decades. The intensity and mechanism of the driving volcanic process influences the extent and style of the forest damage, with resulting timescales and patterns of regrowth reflecting the nature of initial impacts and local floral, climatic and environmental parameters.

As such, vegetation damage holds potential as a novel proxy for the magnitude and nature of volcanic eruptions. Particularly in the case of volcanic eruptions without recorded observations, vegetation damage could potentially constrain parameters such as tephra-fall deposit thickness, dispersal and pyroclastic density currents (PDC) distribution. Additionally, mapping the initial impact and trajectories of recovery are key to understanding the long-term environmental consequences of volcanic eruptions. Here, we aim to constrain eruption magnitudes and deposit volumes, particularly in remote environments, using optical (Landsat 8, Sentinel-2) and radar (Sentinel-1) satellite data to study forest disturbance and recovery following an explosive volcanic eruption in Southern Chile: the 2015 eruption of Calbuco volcano.

The 2015 eruption of Calbuco consisted of three explosive episodes between the 22^nd-23^rd of April resulting in buoyant ash plumes depositing tephra over 100s km², pyroclastic flows reaching over 6km and lahars reaching over 15km. Thus, different intensities and spatial extents of damage were experienced by the surrounding temperate broadleaf forests. We identify areas impacted by the different eruptive deposits using the disturbance and recovery signatures from the optical and radar satellite data. We observe a decrease in vegetation coverage and health immediately following the eruption in the areas impacted by PDCs, lahars and tephra. PDC impacted regions exhibit the greatest decrease in vegetation coverage and health, and consequently a much slower vegetation recovery rate. We develop a satellite-based methodology through time series analysis and cluster analysis to understand the impact of explosive volcanic eruption on vegetation properties. This allows us to assess the extent and severity of forest disturbance caused by the eruption and to map the rates of post-eruption vegetation recovery. We hope to expand this methodology to be applied to different ecosystems and for different styles of eruption using freely available satellite data. With the eventual aim of developing a toolkit for identifying the footprint of past volcanic eruptions on forest environments.

How to cite: Udy, M., Ebmeier, S., Watt, S., and Hooper, A.: Constraining explosive volcanic eruption parameters and environmental impacts using remote sensing observations of forest disturbance and recovery., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15840, https://doi.org/10.5194/egusphere-egu24-15840, 2024.

Volcanic eruptions impact human populations and the environment, with volcanic ash contributing to these effects through its influence on air quality, agriculture, and air transportation. Traditional satellite observation methods for monitoring volcanic ash encounter several challenges, including distinguishing ash from other aerosols, coverage area limitations, frequency of observations, and the impact of adverse weather and atmospheric conditions. These issues highlight the need for supplementary satellite-based approaches to improve volcanic ash monitoring. This project introduces a new method that utilizes machine learning techniques to analyze UV and visible satellite data for detecting and classifying volcanic ash. The research focuses on exploring how satellite UV and visible light observations can be used to identify volcanic ash in the atmosphere. A classifier was developed using simulations from a radiative transfer model, which represents various atmospheric scenarios. This classifier is then applied to analyze spectral measurements obtained by the TROPOspheric Monitoring Instrument (TROPOMI) on the ESA Sentinel-5p satellite. The complexity of detecting and classifying volcanic ash arises not only from the presence of other aerosols in the atmosphere but also from the changing characteristics of the ash, influenced by the type of magma and ongoing alterations as the ash remains airborne. This research presents progress in tackling these challenges and in developing a complex algorithm that incorporates a wide range of parameters. The application of this method to the Raikoke eruption case study enables the identification of some volcanic ash, illustrating the potential of this approach. However, this case study also reveals the presence of misclassifications, highlighting the need for continuous improvement in the classifier. This research offers valuable insights into the detection and classification of volcanic ash, contributing to the enhancement of monitoring strategies for hazard mitigation.

How to cite: Azoulay, A., Hedlt, P., and Efremenko, D.: Detection and classification of volcanic ash based on satellite UV/VIS measurements , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19256, https://doi.org/10.5194/egusphere-egu24-19256, 2024.

Ground-based observation of volcanic ash clouds after an eruption is currently done using weather radars which were originally designed for monitoring meteorological clouds. As ash particles and aggregates have different sizes and refractive indices compared to raindrops and ice crystals, certain parts of the volcanic ash cloud can go undetected by these low frequency weather radars. This can lead to incorrect predictions from the volcanic ash transport prediction models to the aviation industry; the field could benefit from higher frequency radars designed exclusively for ash cloud monitoring. However, the increased sensitivity to fine ash from high frequency signals comes at a cost of significant path attenuation as the wavelengths (in the order of millimeters) are comparable to the ash sizes, and any selection of frequencies should take into account the increased attenuation. In this talk we present a radar forward operator ‘SynRad’ that numerically simulates the radar measurement process and generates synthetic return signals. SynRad is used to evaluate the performance of three radar frequency bands (C-,Ka- and W-bands) to detect a volcanic ash cloud. The numerically simulated volcanic ash cloud of the Redoubt 2009 eruption serves as the case study. Results suggest that a dual-frequency radar with a C- and Ka-band is the best option to detect the predominantly larger ash particles and aggregates at the early stages of the eruption and the fine ash in the distal ash cloud during the later stages of the eruption respectively. The W-band radar undergoes heavy attenuation at all locations except for downwind of the ash cloud. 

How to cite: Nair, V., Mohanathan, A., Herzog, M., Macfarlane, D., and Ferguson, D.: Millimeter wave radars: the way forward for remote sensing of ash plumes?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14074, https://doi.org/10.5194/egusphere-egu24-14074, 2024.

From 18 January to 23 October 2021, 58 paroxysmal events occurred at Mt. Etna volcano by the South East Crater (SEC). Three events, that occurred on 4, 12 March and 24 June, were selected to be studied through a plume dispersion modelling approach. All the selected paroxysms generated ash-SO₂ rich plumes ranging from 6 to 8.5 km above the main vent.
In this work, we explored the spatial dispersion of the volcanic SO₂ plume in each paroxysmal event by using the Weather Research and Forecasting Chemistry (WRF-Chem) model coupled with the time-variable ground-based SO₂ flux emission data recorded by FLAME (FLux Automatic MEausurement) scanning spectrometers network managed by INGV-OE (Osservatorio Etneo). In this context, WRF-Chem was specially configured to run with variable Eruption Source Parameters (ESPs), reading at each integration time-step experimentally measured SO₂ flux values.
The SO₂ maps resulting from the WRF-Chem simulations were compared with the dispersion pattern detected by TROPOMI sensor onboard Sentinel-5p satellite, in order to validate the capability of the model in reproducing the volcanic plume dispersion. The comparison for each simulation highlights a very good agreement between simulated data and those observed by the satellite.
The ash transport was also modelled in each simulation, considering an ash Mass Eruption Rate (MER) which was inverted from the plume height. The spatial evolution of the ash patterns was compared with data retrieved from the MGS-SEVIRI satellite. The comparison shows a good agreement between simulated and observed maps. Particularly for the 12 March event, the ash comparison clearly shows that the WRF-Chem model was able to well reproduce the eastward path of the ash cloud, even at long distances, as the simulated plume reached Greece about 10 hours after the paroxysm, in agreement with satellite observations.
In conclusion, the obtained results testify that the WRF-Chem model can efficiently reproduce the dispersion of both SO₂ and ash plume emitted from Mt. Etna volcano over the Mediterranean basin, representing a powerful tool for assessing air quality, flying security and other hazard factors due to volcanic plume transport and deposition from local to Mediterranean scale. In addition, the performed simulations highlighted that the ground-based data measured by the FLAME network play a key role in improving the accuracy in simulating the SO₂ dispersion pattern as it allows us to take into account the fluctuating and not stationary nature of volcanic plume emissions.

How to cite: Semprebello, A., Salerno, G., Gattuso, A., Sellitto, P., Caccamo, M. T., Longo, M., and Magazù, S.: The 2021 paroxysmal events at Mt. Etna: Modelling of SO2 and volcanic ash dispersion by using WRF-Chem model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18896, https://doi.org/10.5194/egusphere-egu24-18896, 2024.

Understanding the relationship between volcanic eruptions and their associated climate response requires a view extending further back than historical records can provide. Polar ice cores offer one of the best continuous records of past volcanism in the form of sulphates and ash particles preserved in the ice. Because of their light scattering effect, these sulphate aerosols are the dominant volcanic product contributing to annual and muti-annual climate perturbations. The ice-core sulphate record underpins our ability to reconstruct the climate forcing potential of past eruptions but translating the sulphate concentrations within polar ice cores to atmospheric sulphate loading requires knowledge of the volcanic source’s latitude and plume height. While geochemical analysis of the ash particles can identify the source volcano, for prehistoric eruptions there is no primary record of plume height information available.

Here we assess the efficacy of ash dispersion modelling to predict minimum plume height, eruption season and meteorological conditions for events in which there is knowledge only of the source volcano, ash deposition at a given distal location, and ash grain size and shape. We use the eruption of Novarupta-Katmai 1912 as a case study, as ash from this eruption has previously been identified in the North Greenland Ice Core Project (NGRIP) ice core. Using Ash3d software, we model ash dispersion from Novarupta using historical information about the eruption and meteorology to evaluate the sensitivities of the model to parameters such as total grain size distribution, particle shape, ash cloud concentrations over the deposition site and duration of the suspended ash cloud. Using size and shape data from the NGRIP Novarupta-Katmai ash and randomly sampled values of erupted mass, column height, start dates tied to NCEP-NCAR Reanalysis meteorological data, and eruption duration, we run Ash3d simulations of a large series of eruptions from Novarupta, to compare conditions common to “successful” simulations (i.e., those that deposit ash at NGRIP coring site) with known parameters. Our results show that particle shape and size influence the longevity of the ash cloud, requiring longer simulation runs to ensure deposition is captured. We consider the value and limitations of our approach for reconstructing past volcanic plumes and the potential for further developments to aid in our knowledge of past volcanic impacts on climate.

How to cite: Plunkett, G., Mastin, L., and Schwaiger, H.: Ash dispersion modelling as a tool to constrain source parameters of past volcanic eruptions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7784, https://doi.org/10.5194/egusphere-egu24-7784, 2024.

Volcanic lightning during explosive eruptions has been suggested has a key process in the abiotic nitrogen fixation in the early Earth. Although laboratory experiences and thermodynamic models convincingly suggest that volcanic lightning can fix atmospheric nitrogen (e.g. Navarro-Gonzalez et al., 1998, Martin et al., 2007). No geological archives of N-fixed by volcanic lightning have been found yet. Recently, high nitrate concentrations in volcanic deposits from large Neogene explosive eruptions (VEI>7; Aroskay et al. 2023) have been discovered. It is tempting to infer that these nitrates correspond to the end-product of N-fixation by volcanic lightning. However long-term atmospheric deposition of nitrate is suggested to be responsible of nitrate deposits in arid environment (e.g. Atacama Desert and Mojave Desert – Michalski et al. 2004, Lybrand et al. 2013). Therefore, the long-term atmospheric deposition could contribute to nitrates preserved in volcanic deposits.

Our study aims to distinguish the origin of nitrates in volcanic deposits: end-product of volcanic lightning or long term atmospheric deposition? To answer this question, volcanic samples from super-eruptions as well as sediments have been collected in the Tecopa Basin – California, USA. The whole sedimentary column (sediments interspersed with volcanic deposits) has been preserved in the same arid conditions for the last 2Ma. The multi-isotopic composition of nitrate has been measured (δ¹⁸O, δ¹⁵N and Δ¹⁷O) and shows clear distinction between nitrate from volcanic deposits and those from sediments. It appears that while nitrate from sediments result from a mix between atmospheric nitrate and biogenic nitrate, in volcanic deposit the nitrate are most likely the end product of volcanic lightning.

As a conclusion, we demonstrate that volcanic deposits can be an archive of N-fixation by volcanic lightning. This is an open window on the direct quantification of N-fixation by large explosive volcanic eruptions and their role on the development of life on the early Earth.

How to cite: Contamine, D., Martin, E., Aroskay, A., Bekki, S., Szopa, S., and Savarino, J.: Nitrates Production by Volcanic lightning during Explosive Eruptions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13523, https://doi.org/10.5194/egusphere-egu24-13523, 2024.