Lava lake

Amazing Landsat 8 image of Nyiragongo and Nyamulagira volcanoes!

/ besmets
Landsat 8 image acquired on 9th February 2015, over Nyiragongo and Nyamulagira volcanoes. Source: USGS EROS Data Center

Landsat 8 image acquired on 9th February 2015, over Nyiragongo and Nyamulagira volcanoes.
Image source: USGS EROS Data Center

[FR] Le 9 février 2015, le satellite américain Landsat 8 a pris une image exceptionnelle des volcans Nyiragongo et Nyamulagira, tous deux situés dans l’est de la République Démocratique du Congo. L’absence (rare) de couverture nuageuse permet en effet de voir les deux volcans actifs émettre un panache de gaz permanent poussé vers le sud-ouest par les vents dominants. Mais le plus impressionnant provient des bandes spectrales situées dans l’infrarouge. Quand on combine les bandes 5, 6 et 7 de l’image Landsat 8, le lac de lave de chaque volcan apparaît sous la forme d’un halo lumineux (voir image ci-dessous). Profitez bien de cette magnifique image !

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[EN] On 9th February 2015, the US Landsat 8 satellite took an exceptional image of Nyiragongo and Nyamulagira volcanoes, both located in Eastern Democratic Republic of Congo. The absence (infrequent) of a dense cloud cover allows to observe these two highly active volcanoes emitting a permanent gas plume driven southwestward by the dominant winds. But, the most amazing thing comes from the infrared spectral bands. When bands 5, 6 and 7 of the Landsat 8 image are combined, the lava lake of each volcano appears as a halo of light (see image hereafter). Enjoy this beautiful image!

RGB-composite image, with bands 5, 6 and 7 of the Landsat 8 image. Image source: USGS EROS Data Center

RGB-composite image, with bands 5, 6 and 7 of the Landsat 8 image. Image source: USGS EROS Data Center

First geocoded 3D model of the Nyiragongo crater!

/ besmets
Screenshot of a zoom in the orthophoto of the Nyiragongo crater, recently produced thanks to photographs acquired from a helicopter, in July 2014.

THIS IS NOT A PHOTOGRAPH. 😉   –   Screenshot of a zoom in the orthophoto of the Nyiragongo crater, recently produced thanks to photographs acquired from a helicopter, in July 2014. (Image acquisition realized with the support of Nikon BeLux)

[FR] Grâce aux photographies récoltées par hélicoptère en juillet 2014 (et grâce à un léger changement de stratégie dans le traitement des données), j’ai le plaisir d’annoncer la sortie d’un premier modèle numérique de terrain (MNT) du cratère principal du Nyiragongo.

Ce MNT a été produit à une résolution de 58 cm et couvre la majeure partie du cratère. Seules les parties cachées par le panache de gaz volcanique et le haut des flancs supérieurs n’ont pas été modélisés.

Le MNT est accompagné d’une orthophoto produite à une résolution de 15 cm. Les détails dans cette image (voir photo) sont à couper le souffle. Grâce à ces deux images nouvellement produites, je vais enfin pouvoir clôturer un des objectifs majeurs de ma thèse. … à 3 mois de la fin, il était temps ! 🙂

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[EN] Thanks to photos acquired from a helicopter, in July 2014, (and thanks to small changes in the processing strategy) I have the pleasure to announce the release of a first digital elevation model (DEM) of the Nyiragongo main crater.

This DEM has a spatial resolution of 58 cm and covers almost all the main parts of the crater. Only parts hidden by the volcanic gas plume and the upper flanks were not modeled.

The DEM comes with an orthophoto, which has a spatial resolution of 15 cm. Details in this image (see photo) are breathtaking. Thanks to these two newly produced images, I will finally be able to complete one of the main objectives of my Thesis. … 3 months left, it was time! 🙂

Recent eruptive activity at Nyamulagira: there is currently NO LAVA LAKE.

/ besmets

First publication: 10 September 2014
Updated: 21 October 2014

Sporadically from April 2014, then more systematically since 22nd June 2014, a red glow has become visible on top of Nyamulagira (or Nyamuragira), the most western volcano of the Virunga Volcanic Province. On 1st  and 5th July 2014, helicopter flights confirmed the presence of lava fountains in the 400 × 600 m-wide pit crater located in the NE sector of the caldera.

First information on the Internet about this new eruptive activity came from the NASA Earth Observatory [1], which published a satellite image acquired by Landsat 8 on 30th June 2014, where a strong red glow is visible in the Nyamulagira caldera.  NASA said that a new lava lake appeared at Nyamulagira, but field observations deny this affirmation. Indeed, if the red glow on the Landsat image looks similar to the one caused by the Nyiragongo lava lake, it is however caused by fire fountains. So, currently, there is no active lava lake sensu stricto at Nyamulagira

Unfortunately, this misleading information was quickly relayed on several websites (e.g. [2] [3]) and even in scientific literature [4], as it is often the case for this volcano and the neighbouring Nyiragongo.

More (correct) information about this activity has been published in EOS Transactions. In addition, images of this activity, which were acquired in early July 2014 by N. d’Oreye, F. Kervyn and me during helicopter flights and field work in the Nyamulagira caldera, are available here (Click on the image below).

Fire fountains observed in the pit crater located in the NE part of the Nyamulagira caldera, on 1st July 2014. Photo (c) B. Smets

Fire fountains observed in the pit crater located in the NE part of the Nyamulagira caldera, on 1st July 2014.
Photo: (c) B. Smets – 2014