jump to navigation

Alu/Dalaffilla fissure eruption at the NASA Earth Observatory 6 February 2009

Posted by admin in Africa, Alu, Dalaffilla, eruptions, Ethiopia, NASA Earth Observatory.
Tags: , , , , ,
comments closed

November 2008 Alu/Dalaffilla Fissure Eruption (NASA Earth Observatory. Formosat image copyright 2008 Dr Cheng-Chien Liu, National Cheng-Kung University, and Dr An-Ming Wu, National Space Organization, Taiwan.)

The NASA Earth Observatory image of the day for 4 February 2009 is a crystal-clear Formosat-2 true-colour image of the Alu/Dalaffilla area of the Afar region of north-eastern Ethiopia, for which I have written the caption. This is the place where a notable fissure eruption occurred in November 2008 (see earlier coverage at the Earth Observatory).

The original image (reduced size version above) is available at 720 x 540 pixels and a huge and beautiful 7700 x 9720 pixels (7MB). For the full picture visit the Earth Observatory, and do also have a look at the other wonderful images of the day, going back to 1999, available via the Image of the Day index page.

(Credit: NASA Earth Observatory. Formosat image copyright 2008 Dr Cheng-Chien Liu, National Cheng-Kung University, and Dr An-Ming Wu, National Space Organization, Taiwan.)

Information
Global Volcanism Program: Dalaffilla – information about Dalaffilla (0201-07=)
Global Volcanism Program: Alu – information about Alu (0201-06=)
Global Volcanism Program: volcanoes of Africa (northeastern) and the Red Sea – regional list of volcanoes from the Global Volcanism Program

The Volcanism Blog

Alu/Dalaffilla eruption – photographs 19 December 2008

Posted by admin in activity reports, Africa, Alu, Dalaffilla, eruptions, Ethiopia, geoblogosphere.
Tags: , , , ,
comments closed

In November an eruption occurred in the Afar region of north-east Ethiopia. Two pictures of that eruption from ground level have been published by Sylvie and Daniel Chereau’s volcano site: they were taken by Claude-Henri Mussat on 3 and 4 November and show a lofty plume. The pictures are copyrighted, so are not reproduced here – click on the link above to view.

In a new post today at the same site, there is an interesting (French language) summary, with many images, of the debate over the location of the eruption: Alu, Dalaffilla, or a point in between? The evidence from satellite imagery is strongly in favour of the latter – a fissure eruption from between Alu and Dalaffilla – but the possibility remains that the two volcanic centres are part of the same complex. More research needed …

For more on the Ethiopian eruption: Ethiopia « The Volcanism Blog.

The Volcanism Blog

Ethiopia eruption at NASA Earth Observatory 19 November 2008

Posted by admin in Africa, Alu, Dalaffilla, eruptions, Ethiopia.
Tags: , , , ,
comments closed

The ‘Image of the Day’ slot at the wonderful NASA Earth Observatory today features the ASTER images of the eruption in the Afar region of Ethiopia that were previewed here yesterday (thanks to our generous friends at NASA). There is an informative commentary and links to very large versions of the original images – 2000 pixels square, around 4MB – which reveal a lot of detail. It is clear from these that the origin of this eruption lies between Alu and Dalaffilla, without showing the precise character of the vents/fissures involved.

Alu/Dalaffilla eruption - ASTER images from 2006 and 2008 (NASA)

Above, detail views of the area of the activity from before and after the eruption (from the large ASTER images) are juxtaposed. The new flows appear to originate from cones along the line of the fissure(s). The south-eastern rim of the Alu horst can be seen at top left, the north-western fringes of Dalaffilla’s cone at bottom right.

N.B. For more discussion of this eruption, see Boris Behncke’s comment on yesterday’s TVB post.

Viewing the Ethiopia category will bring up previous posts from The Volcanism Blog on this eruption.

Information
Global Volcanism Program: Dalaffilla – information about Dalaffilla (0201-07=)
Global Volcanism Program: Alu – information about Alu (0201-06=)
Global Volcanism Program: volcanoes of Africa (northeastern) and the Red Sea – regional list of volcanoes from the Global Volcanism Program

The Volcanism Blog

ASTER imagery of Ethiopia eruption 18 November 2008

Posted by admin in activity reports, Africa, Alu, Dalaffilla, eruptions, Ethiopia.
Tags: , , , , ,
comments closed

Alu and Dalaffilla, before and after the November 2008 eruption (NASA ASTER imagery)

On 16 November the ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) equipment aboard NASA’s Terra satellite acquired the area of north-east Ethiopia where the volcanic eruption took place on 3 November 2008. The ASTER data provides the clearest imagery made available to date. On the evidence of these images it is a fissure vent zone between Alu and Dalaffilla, rather than Dalaffilla volcano, which is responsible for the current eruption.

Our thanks to Rob Simmon of NASA for these images. For more NASA satellite imagery, visit the NASA Earth Observatory.

ASTER image of Dalaffilla and Alu, 5 Feb 2006, reduced (NASA)
Figure 1. The Alu/Dalaffilla area captured on 5 February 2006, before the current eruption. To see a larger version in a new window, click here.

ASTER image of Dalaffilla and Alu, 16 Nov 2008, reduced (NASA)
Figure 2. The Alu/Dalaffilla area captured on 16 November 2008, after the current eruption began. A new, large dark lava flow is evident, covering a large area and extending about 12km to the east and north. The main cone of Dalaffilla, in the lower centre of the image, shows no signs of activity. To see a larger version of this image in a new window, click here.

ASTER image of Dalaffilla and Alu, 5 Feb 2006, detail (NASA)
Figure 3. Close-up of the Alu/Dalaffilla volcanic zone from the 2 February 2006 image.

ASTER image of Dalaffilla and Alu, 11 Nov 2008, detail (NASA)
Figure 4. Close-up of the Alu/Dalaffilla volcanic zone from the 16 November 2008 image.

The lava flow produced by this eruption covers a large area and overlies previously-deposited flows. The Global Volcanism Program summary for Alu describes ‘voluminous youthful basaltic lava flows to the east’, so the current event is clearly the latest in a long line of similar effusive eruptions.

The source of this eruption may well fall between Alu and Dalaffilla and represent the type of basaltic, effusive eruption associated with the former, but the question arises of how far Alu and Dalaffilla are interrelated, perhaps even forming part of the same volcanic complex (this image from Stromboli Online shows how the two features, which are only about 3km apart, relate to one another). Dalaffilla is silicic rather than basaltic, but Alu, which is a complex of fissure vents, also appears to produce silicic lava flows, which emerge from vents on the west of the horst, while basaltic flows originate from vents on the east and to the south. It’s all very interesting.

The latest MODIS imagery and hotspot data for the area indicates that all is quiet at the moment.

[N.B. The first version of this post located Alu closer to Dalaffilla than is actually the case, and as a result was rather more definitive in attributing the eruption to Alu than was justified. Alu is a volcanic horst and can be identified as the rounded shape on the left edge of the ASTER images - a comparison with this picture at the Global Volcanism Program confirms the identification. However, the style and location of this eruption suggests that Alu's southern fissures ('fissures to the south have produced voluminous youthful basaltic lava flows', says the GVP caption) have more to do with it than any flank activity originating at Dalaffilla.]

Viewing the Ethiopia category will bring up previous posts from The Volcanism Blog on this eruption.

Information
Global Volcanism Program: Dalaffilla – information about Dalaffilla (0201-07=)
Global Volcanism Program: Alu – information about Alu (0201-06=)
Global Volcanism Program: volcanoes of Africa (northeastern) and the Red Sea – regional list of volcanoes from the Global Volcanism Program

The Volcanism Blog

Ongoing volcanic activity in north-east Ethiopia 17 November 2008

Posted by admin in activity reports, Africa, Alu, Dalaffilla, eruptions, Ethiopia.
Tags: , , , , , ,
comments closed

The eruptive activity in the Afar region of north-east Ethiopia that began on 3 November is continuing, with substantial effusive lava flows visible on recent MODIS satellite images of the area. Activolcans reported yesterday the presence of ‘a very important thermal anomaly in the Alu volcanic zone, north of Erta Ale’. The MODIS images for the period 12-17 November, generated by the Hawaii Institute of Geophysics and Planetology hotspots website, are as follows:

MODIS images of Ethiopian eruption, 12-17 November 2008 (Hawaii Institute of Geophysics and Planetology)

Viewing the Ethiopia category will bring up previous posts from The Volcanism Blog on this eruption.

Information
Global Volcanism Program: Dalaffilla – information about Dalaffilla (0201-07=)
Global Volcanism Program: Alu – information about Alu (0201-06=)
Global Volcanism Program: volcanoes of Africa (northeastern) and the Red Sea – regional list of volcanoes from the Global Volcanism Program

The Volcanism Blog

Ethiopian eruption – further coverage 10 November 2008

Posted by admin in Africa, Alu, Dalaffilla, Erta Ale, eruptions, Ethiopia, geoscience.
Tags: , , , , , ,
comments closed

NASA’s Earth Observatory has a feature today on one of the MODIS images of the eruption in the Afar region of north-east Ethiopia, captured by NASA’s Aqua satellite on 4 November, that have been discussed here in an earlier post: Activity on the Erta Ale Range.

This link came via Geology.com, who also have a very useful article on the wider geological context for all that’s going on in the Ethiopian Rift: East Africa’s Great Rift Valley: A Complex Rift System (by James Wood and Alex Guth). For further background reading, try this article from Spiegel Online, March 2006: Africa’s New Ocean: A Continent Splits Apart.

Viewing the Ethiopia category will bring up previous posts from The Volcanism Blog on this eruption.

The Volcanism Blog

Volcanic eruption in Ethiopia – more MODIS 10 November 2008

Posted by admin in activity reports, Africa, Alu, Dalaffilla, eruptions, Ethiopia.
Tags: , , , , ,
comments closed

The excellent French site Activolcans has two new despatches on the Ethiopian eruption of 3 November 2008.

The first report, from 8 November, notes the evidence of activity detected by MODIS in the vicinity of Alu volcano between 3 and 7 November: ‘a series of thermal anomalies aligned in a north-easterly direction. This suggests that the effusive activity was continuing at this time’. Activolcans has ‘without absolute certainty’ provisionally concluded that Alu rather than Dalaffilla has erupted, given the evidently basaltic, low-viscosity, effusive character of this eruption (Dalaffilla is a silicic stratovolcano, while Alu is a system of fissures with a recent history of extensive effusive activity). For more on this, see the comment from Activolcans on an earlier post here at TVB, and Ron Schott’s comment on this post at Eruptions.

A second report on 9 November notes a further large thermal anomaly oriented towards the north-east and 10-12km in length, and an ongoing eruption of SO2 in the vicinity of Alu volcano.

The MODIS data referred to by the Activolcans report can be seen below in images from the Hawaii Institute of Geophysics and Planetology hotspots website.

NASA MODIS image for the Afar region, 7 November 2008 (Hawaii Institute of Geophysics and Planetology)
Above: MODIS image from 7 November 2008.

NASA MODIS image for the Afar region, 8 November 2008 (Hawaii Institute of Geophysics and Planetology)
Above: MODIS image from 8 November 2008.

NASA MODIS image for the Afar region, 9 November 2008 (Hawaii Institute of Geophysics and Planetology)
Above: MODIS image from 9 November 2008.

It still isn’t possible to be definitive about the origin of the eruption. This is a very complex setting, with fissures and subsidiary cones and vents scattered across and between the main volcanic features (some ASTER imagery of the area can be found in the NASA ASTER Volcano Archive), so the current activity may well be from neither Alu nor Dalaffilla, but from fissures in between. On balance, however, as Activolcans notes, it seems to originate more from the area of Alu, and to partake more of the eruptive character of Alu than that of Dalaffilla. But we’ll have to wait to see what further evidence comes in…

Viewing the Ethiopia category will bring up previous posts from The Volcanism Blog on this eruption.

Information
Global Volcanism Program: Dalaffilla – information about Dalaffilla (0201-07=)
Global Volcanism Program: Alu – information about Alu (0201-06=)
Global Volcanism Program: volcanoes of Africa (northeastern) and the Red Sea – regional list of volcanoes from the Global Volcanism Program

The Volcanism Blog

Follow

Get every new post delivered to your Inbox.

Join 124 other followers