Analyzing the 2011 eruption of Nabro volcano using satellite remote sensing and numerical modeling of lava flows

2020 ◽  
Author(s):  
Ciro Del Negro ◽  
Gaetana Ganci ◽  
Annalisa Cappello ◽  
Giuseppe Bilotta ◽  
Claudia Corradino
Keyword(s):  
Remote Sensing ◽  
Numerical Modeling ◽  
Lava Flow ◽  
Satellite Remote Sensing ◽  
Discharge Rate ◽  
Lava Flows ◽  
Maximum Speed ◽  
High Temporal Resolution ◽  
Monitoring Networks ◽  
Maximum Extent

<p>The 2011 eruption of Nabro volcano, situated at the southeast end of the Danakil Alps in Eritrea, has been the first historical on record and one of the largest eruptions of the last decade. Due to the remote location of the Nabro volcano and the lack of data from ground monitoring networks at the time of the eruption, satellite remote sensing gives the first global view of the event, providing insights on its evolution over time. Here we used numerical modeling and high spatial resolution satellite data (i.e. EO-ALI, ASTER, PlanetScope) to track the path and velocity of lava flows and to reconstruct the pre- and post-eruptive topographies in order to quantify the total bulk volume emitted. High temporal resolution images (i.e. SEVIRI and MODIS) were exploited to estimate the time-averaged discharge rate (TADR) and assess the dense rock equivalent (DRE) lava volumes constrained by the topographic approach. Finally, satellite-derived parameters were used as input and validation tags for the numerical modelling of lava flow scenarios, offering further insights into the eruption and emplacement dynamics. We found that the total volume of deposits, calculated from differences of digital elevation models (DEMs), is about 580 × 10<sup>6</sup> m<sup>3</sup>, of which about 336 × 10<sup>6</sup> m<sup>3</sup> is the volume of the main lava flow that advanced eastward beyond the caldera. Multi-spectral satellite observations indicate that the main lava flow had reached its maximum extent (∼16 km) within about 4 days of the eruption onset on midnight 12 June. Lava flow simulations driven by satellite-derived parameters allow building an understanding of the advance rate and maximum extent of the main lava flow showing that it is likely to have reached 10.5 km in one day with a maximum speed of ~0.44 km/h.</p>

scholarly journals Sea ice circulation in the Laptev Sea and ice export to the Arctic Ocean: Results from satellite remote sensing and numerical modeling

2000 ◽  
Vol 105 (C7) ◽  
pp. 17143-17159 ◽  
Author(s):  
Vitaly Y. Alexandrov ◽  
Thomas Martin ◽  
Josef Kolatschek ◽  
Hajo Eicken ◽  
Martin Kreyscher ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Numerical Modeling ◽  
Sea Ice ◽  
Arctic Ocean ◽  
Satellite Remote Sensing ◽  
The Arctic ◽  
Laptev Sea ◽  
The Arctic Ocean ◽  
The Laptev Sea

scholarly journals Hazards from lava–river interactions during the 1783–1784 Laki fissure eruption

2020 ◽  
Vol 132 (11-12) ◽  
pp. 2651-2668
Author(s):  
Frances Boreham ◽  
Katharine Cashman ◽  
Alison Rust
Keyword(s):  
Remote Sensing ◽  
Surface Water ◽  
Lava Flow ◽  
Field Studies ◽  
Fissure Eruption ◽  
Lava Flows ◽  
Aerial Photographs ◽  
Geological Evidence ◽  
Digital Terrain ◽  
Remote Mapping

Abstract Interactions between lava flows and surface water are not always considered in hazard assessments, despite abundant historical and geological evidence that they can create significant secondary hazards (e.g., floods and steam explosions). We combine contemporary accounts of the 1783–1784 Laki fissure eruption in southern Iceland with morphological analysis of the geological deposits to reconstruct the lava–water interactions and assess their impact on residents. We find that lava disrupted the local river systems, impounded water that flooded farms and impeded travel, and drove steam explosions that created at least 2979 rootless cones on the lava flow. Using aerial photographs and satellite-derived digital terrain models, we mapped and measured 12 of the 15 rootless cone groups on the Laki lava field. We have identified one new rootless cone group and provide data that suggest another cone group previously attributed to the 939–940 CE Eldgjá eruption was created by the Laki eruption. We then use contemporary accounts to estimate formation dates and environments for each cone group, which formed in wetland/lake areas, on riverbeds, and near areas of impounded water. Furthermore, comparison with previous field studies shows that assessments using remote sensing can be used to identify and map meter-scale and larger features on a lava flow, although remote mapping lacks the detail of field observations. Our findings highlight the different ways in which lava can interact with surface water, threatening people, property, water supplies, and infrastructure. For these reasons, anticipation of such interactions is important in lava flow hazard assessment in regions with abundant surface water; we further demonstrate that remote sensing can be an effective tool for identifying lava–water interactions in past lava flows.

scholarly journals A novel methodology for large-scale daily assessment of the direct radiative forcing of smoke aerosols

2015 ◽  
Vol 15 (10) ◽  
pp. 5471-5483 ◽  
Author(s):  
E. T. Sena ◽  
P. Artaxo
Keyword(s):  
Remote Sensing ◽  
Spatial Distribution ◽  
Radiative Transfer ◽  
Biomass Burning ◽  
Satellite Remote Sensing ◽  
Radiative Forcing ◽  
High Temporal Resolution ◽  
Radiation Balance ◽  
Direct Radiative Forcing ◽  
The Impact

Abstract. A new methodology was developed for obtaining daily retrievals of the direct radiative forcing of aerosols (24h-DARF) at the top of the atmosphere (TOA) using satellite remote sensing. Simultaneous CERES (Clouds and Earth's Radiant Energy System) shortwave flux at the top of the atmosphere and MODIS (Moderate Resolution Spectroradiometer) aerosol optical depth (AOD) retrievals were used. To analyse the impact of forest smoke on the radiation balance, this methodology was applied over the Amazonia during the peak of the biomass burning season from 2000 to 2009. To assess the spatial distribution of the DARF, background smoke-free scenes were selected. The fluxes at the TOA under clean conditions (Fcl) were estimated as a function of the illumination geometry (θ0) for each 0.5° × 0.5° grid cell. The instantaneous DARF was obtained as the difference between the clean (Fcl (θ0)) and the polluted flux at the TOA measured by CERES in each cell (Fpol (θ0)). The radiative transfer code SBDART (Santa Barbara DISORT Radiative Transfer model) was used to expand instantaneous DARFs to 24 h averages. This new methodology was applied to assess the DARF both at high temporal resolution and over a large area in Amazonia. The spatial distribution shows that the mean 24h-DARF can be as high as −30 W m−2 over some regions. The temporal variability of the 24h-DARF along the biomass burning season was also studied and showed large intraseasonal and interannual variability. We showed that our methodology considerably reduces statistical sources of uncertainties in the estimate of the DARF, when compared to previous approaches. DARF assessments using the new methodology agree well with ground-based measurements and radiative transfer models. This demonstrates the robustness of the new proposed methodology for assessing the radiative forcing for biomass burning aerosols. To our knowledge, this is the first time that satellite remote sensing assessments of the DARF have been compared with ground-based DARF estimates.

scholarly journals Satellite and Ground Remote Sensing Techniques to Trace the Hidden Growth of a Lava Flow Field: The 2014-15 Effusive Eruption at Fogo Volcano (Cape Verde)

2018 ◽  
Author(s):  
Sonia Calvari ◽  
Gaetana Ganci ◽  
Sónia Silva Victória ◽  
Pedro A. Hernandez ◽  
Nemesio Perez ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Flow Field ◽  
Lava Flow ◽  
Rapid Expansion ◽  
Lava Flows ◽  
Key Factors ◽  
Supply Rate ◽  
Eruptive Fissure ◽  
Lava Flow Field ◽  
Fogo Volcano

Fogo volcano erupted in 2014-15 producing an extensive lava flow field in the summit caldera that destroyed two villages, Portela and Bangaeira. The eruption started with powerful explosive activity, lava fountains, and a substantial ash column accompanying the opening of an eruptive fissure. Lava flows spreading from the base of the eruptive fissure produced three arterial lava flows. By a week after the start of the eruption, a master lava tube had already developed within the eruptive fissure and along the arterial flow. In this paper, we analyze the emplacement processes on the basis of observations carried out directly on the lava flow field, remote sensing measurements carried out with a thermal camera, SO2 fluxes, and satellite images, in order to unravel the key factors leading to the development of lava tubes. These were responsible for the rapid expansion of lava for the ~7.9 km length of the flow field, as well as the destruction of the Portela and Bangaeira villages. The key factors leading to the development of tubes were the low topography and the steady magma supply rate along the arterial lava flow. Comparing time-averaged effusion rates (TADR) obtained from satellite and Supply Rate (SR) derived from SO2 flux data, we estimate the amount and timing of the lava flow field endogenous growth, with the aim of developing a tool that could be used for hazard assessment and risk mitigation at this and other volcanoes.

scholarly journals Evaluating the potential of remote sensing imagery in mapping ground-level fine particulate matter (PM2.5) for the Vaal Triangle Priority Area

2020 ◽  
Vol 30 (1) ◽  
Author(s):  
Luckson Muyemeki ◽  
Roelof Burger ◽  
Stuart J. Piketh
Keyword(s):  
South Africa ◽  
Remote Sensing ◽  
Satellite Remote Sensing ◽  
Fine Particulate Matter ◽  
Temporal Trends ◽  
Ground Level ◽  
Monitoring Networks ◽  
Priority Area ◽  
Satellite Retrievals ◽  
Vaal Triangle

The quality of air breathed in South Africa is of great concern, especially in industrialised regions where PM2.5 concentrations are high. Long term exposure to PM2.5 is associated with serious adverse health impacts. Traditionally, PM2.5 is monitored by a network of ground-based instruments. However, the coverage of monitoring networks in South Africa is not dense enough to fully capture the spatial variability of PM2.5 concentrations. This study explored whether satellite remote sensing could offer a viable alternative to ground-based monitoring. Using an eight-year record (2009 to 2016) of satellite retrievals (MODIS, MISR and SeaWIFS) for PM2.5 concentrations, spatial variations and temporal trends for PM2.5 are evaluated for the Vaal Triangle Airshed Priority Area (VTAPA). Results are compared to corresponding measurements from the VTAPA surface monitoring stations. High PM2.5 concentrations were clustered around the centre and towards the south-west of the VTAPA over the highly industrialised cities of Vanderbijlpark and Sasolburg. Satellite retrievals tended to overestimate PM2.5 concentrations. Overall, there was a poor spatial agreement between satellite-retrieved PM2.5 estimates and ground-level PM2.5 measurements. Root mean square error values ranged from 6 to 11 µg/m3 and from -0.89 to 0.32 for the correlation coefficient. For satellite remote sensing to be effectively exploited for air quality assessments in the VTAPA and elsewhere, further research to improve the precision and accuracy of satellite-retrieved PM2.5 is required.

scholarly journals Satellite and Ground Remote Sensing Techniques to Trace the Hidden Growth of a Lava Flow Field: The 2014–2015 Effusive Eruption at Fogo Volcano (Cape Verde)

2018 ◽  
Vol 10 (7) ◽  
pp. 1115 ◽  
Author(s):  
Sonia Calvari ◽  
Gaetana Ganci ◽  
Sónia Victória ◽  
Pedro Hernandez ◽  
Nemesio Perez ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Flow Field ◽  
Lava Flow ◽  
Rapid Expansion ◽  
Lava Flows ◽  
Key Factors ◽  
Supply Rate ◽  
Eruptive Fissure ◽  
Lava Flow Field ◽  
Fogo Volcano

Fogo volcano erupted in 2014–2015 producing an extensive lava flow field in the summit caldera that destroyed two villages, Portela and Bangaeira. The eruption started with powerful explosive activity, lava fountains, and a substantial ash column accompanying the opening of an eruptive fissure. Lava flows spreading from the base of the eruptive fissure produced three arterial lava flows. By a week after the start of the eruption, a master lava tube had already developed within the eruptive fissure and along the arterial flow. In this paper, we analyze the emplacement processes based on observations carried out directly on the lava flow field, remote sensing measurements carried out with a thermal camera, SO2 fluxes, and satellite images, to unravel the key factors leading to the development of lava tubes. These were responsible for the rapid expansion of lava for the ~7.9 km length of the flow field, as well as the destruction of the Portela and Bangaeira villages. The key factors leading to the development of tubes were the low topography and the steady magma supply rate along the arterial lava flow. Comparing time-averaged discharge rates (TADR) obtained from satellite and Supply Rate (SR) derived from SO2 flux data, we estimate the amount and timing of the lava flow field endogenous growth, with the aim of developing a tool that could be used for hazard assessment and risk mitigation at this and other volcanoes.

scholarly journals Probabilistic forecast of microcystin toxin using satellite remote sensing, in situ observations and numerical modeling

2020 ◽  
Vol 128 ◽  
pp. 104705
Author(s):  
Qianqian Liu ◽  
Mark D. Rowe ◽  
Eric J. Anderson ◽  
Craig A. Stow ◽  
Richard P. Stumpf ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Numerical Modeling ◽  
Satellite Remote Sensing ◽  
Probabilistic Forecast ◽  
In Situ Observations

scholarly journals A novel methodology using MODIS and CERES for assessing the daily radiative forcing of smoke aerosols in large scale over the Amazonia

2014 ◽  
Vol 14 (22) ◽  
pp. 31515-31550
Author(s):  
E. T. Sena ◽  
P. Artaxo
Keyword(s):  
Remote Sensing ◽  
Spatial Distribution ◽  
Radiative Transfer ◽  
Biomass Burning ◽  
Satellite Remote Sensing ◽  
Radiative Forcing ◽  
Large Scale ◽  
High Temporal Resolution ◽  
Modis Aod ◽  
The Impact

Abstract. A new methodology was developed for obtaining daily retrievals of the direct radiative forcing of aerosols (24h-DARF) at the top of the atmosphere (TOA) using satellite remote sensing. For that, simultaneous CERES (Clouds and Earth's Radiant Energy System) shortwave flux at the top of the atmosphere (TOA) and MODIS (Moderate Resolution Spectroradiometer) aerosol optical depth (AOD) retrievals were used. This methodology is applied over a large region of Brazilian Amazonia. We focused our studies on the peak of the biomass burning season (August to September) from 2000 to 2009 to analyse the impact of forest smoke on the radiation balance. To assess the spatial distribution of the DARF, background scenes without biomass burning impacts, were defined as scenes with MODIS AOD < 0.1. The fluxes at the TOA retrieved by CERES for those clean conditions (Fcl) were estimated as a function of the illumination geometry (θ0) for each 0.5° × 0.5° grid cell. The instantaneous DARF was obtained as the difference between clean Fcl (θ0) and the polluted mean flux at the TOA measured by CERES in each cell (Fpol (θ0)). The radiative transfer code SBDART (Santa Barbara DISORT Radiative Transfer model) was used to expand instantaneous DARFs to 24 h averages. With this methodology it is possible to assess the DARF both at large scale and at high temporal resolution. This new methodology also showed to be more robust, because it considerably reduces statistical sources of uncertainties in the estimates of the DARF, when compared to previous assessments of the DARF using satellite remote sensing. The spatial distribution of the 24h-DARF shows that, for some cases, the mean 24h-DARF presents local values as high as −30 W m−2. The temporal variability of the 24h-DARF along the biomass burning season was also studied and showed large intraseasonal and interannual variability. In an attempt to validate the radiative forcing obtained in this work using CERES and MODIS, those results were compared to coincident AERONET ground based estimates of the DARF. This analysis showed that CERES-MODIS and AERONET 24h-DARF are related as DARFCERES-MODIS24 h = (1.07 ± 0.04)DARFAERONET24 h −(0.0 ± 0.6). This is a significant result, considering that the 24h-DARF retrievals were obtained by applying completely different methodologies, and using different instruments. The instantaneous CERES-MODIS DARF was also compared with radiative transfer evaluations of the forcing. To validate the aerosol and surface models used in the simulations, downward shortwave fluxes at the surface evaluated using SBDART and measured by pyranometers were compared. The simulated and measured downward fluxes are related through FBOAPYRANOMETER = (1.00 ± 0.04)FBOASBDART −(20 ± 27), indicating that the models and parameters used in the simulations were consistent. The relationship between CERES-MODIS instantaneous DARF and calculated SBDART forcing was satisfactory, with DARFCERES-MODIS = (0.86 ± 0.06)DARFSBDART −(6 ± 2). Those analysis showed a good agreement between satellite remote sensing, ground-based and radiative transfer evaluated DARF, demonstrating the robustness of the new proposed methodology for calculated radiative forcing for biomass burning aerosols. To our knowledge, this was the first time satellite remote sensing assessments of the DARF were compared with ground based DARF estimates.

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