Except for Figure 1, the images below come from the Moderate Resolution Imaging Spectroradiometer (MODIS) carried aboard NASA’s Terra and Aqua satellites. The Hawaii Institute of Geophysics and Planetology (HIGP) at the University of Hawaii has developed an automatic system that uses the infrared satellite imagery from MODIS to plot thermal anomalies in near real-time, and publishes the results on its hotspots website. The detection of thermal anomalies – hotspots – is of course one of the fundamental tools of volcano monitoring. This post features MODIS images of the recent eruption in north-eastern Ethiopia generated by the HIGP system.
The first map below is an overview of volcanoes the Afar region of north-eastern Ethiopia (as registered by the Global Volcanism Program) from Google Earth, for reference. Below are screen captures from the Hawaii thermal alerts website, showing MODIS data for this region during the period 2-6 November 2008. This data shows the development of the hotspot associated with the eruption of 3 November, and would seem to support the contention that Dalaffilla is the volcano responsible. (Click on ‘more’ to see the MODIS images, which are under the cut.)
Figure 1. Volcanoes of north-eastern Ethiopia, created using Google Earth with the ‘volcanoes’ layer enabled. This layer integrates information from the Global Volcanism Program.
Figure 2. MODIS image for the Afar region, 2 November 2008. Nothing happening, but this gives a good sense of the terrain. In the centre of the image, running SE to NW, is the Danakil Depression with the volcanic Erta Ale ridge forming a kind of inland island in the middle. Erta Ale volcano itself is marked just below right of centre, and the phreatic explosion crater Dallol, formed in 1926, is marked top left.
Figure 3. Image from 3 November 2008. Eruption under way, with the presence of a sizeable heat source: the identification with Dalaffilla seems credible. A smaller hot-spot, interestingly, appears about 20km east of the main event.
Figure 4. Image from 4 November 2008. Indications of lava on the eastern flanks of the ridge.
Figure 5. Image from 5 November 2008.
Figure 6. The situation on 6 November 2008.
Figure 7. Cumulative image of hotspot development, 2-6 November 2008. Figures 2-6 above are reduced from the originals, but these detail views are at full size.
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