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ASTER imagery of Ethiopia eruption 18 November 2008

Posted by admin in activity reports, Africa, Alu, Dalaffilla, eruptions, Ethiopia.
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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

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Ongoing volcanic activity in north-east Ethiopia 17 November 2008

Posted by admin in activity reports, Africa, Alu, Dalaffilla, eruptions, Ethiopia.
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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.
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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.
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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

MODIS true colour imagery of the Ethiopian eruption 7 November 2008

Posted by admin in activity reports, Africa, Alu, Dalaffilla, eruptions, Ethiopia.
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MODIS true colour imagery of the Ethiopian eruption from NASA’s Terra satellite can be found at this link. Click on the links within the page for enlargements.

2008/309 - 04 Nov 0735 UTC - volcanic eruption in Ethiopia (NASA Terra MODIS image)

Above, NASA Terra MODIS true colour imagery of volcanic eruption in Ethiopia, 4 November 2008 (1km per pixel). Red area marks the thermal anomaly. Below, detail showing a close-up of the area of the eruption (250m per pixel).

2008/309 - 04 Nov 0735 UTC - volcanic eruption in Ethiopia (NASA Terra MODIS image). Detail view.

The question now is whether we are looking at Alu or Dalaffilla in eruption, or some fissure in between? The Global Volcanism Program has the following summary on its main page, reflecting the inconclusive nature of the current evidence:

An eruption of a volcano N of Erta Ale in Ethiopia’s Afar region began on 3 November. Satellite imagery showed a large sulfur dioxide cloud that drifted E over the Arabian Peninsula. Extensive thermal anomalies near Alu and Dalaffilla volcanoes were also detected presumably indicating lava flows. According to news articles, observers reported ground shaking, hearing loud noises and explosions from a distance, and seeing smoke. Thermal anomalies continued to be detected during 3-6 November.

We are promised ASTER imagery from NASA within the next few days, which may help to clear the matter up.

Thanks to Robert Simmons of NASA for information received.

The Volcanism Blog

MODIS images of the Ethiopian eruption 7 November 2008

Posted by admin in activity reports, Africa, Dalaffilla, eruptions, Ethiopia.
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[This is an image-heavy post, so most of it is under the cut. Click on ‘more’ below, or on the title above, to view the whole thing.]

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. Starting at the HIGP’s main global thermal alerts page, you can click on the part of the globe you are interested in (or select regions from a drop-down menu, or enter latitude and longitude directly) and zoom in progressively to acquire more detailed views. 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 the Afar region of north-eastern Ethiopia (Google Earth)
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.

(more…)

Ethiopian eruption update 6 November 2008

Posted by admin in activity reports, Africa, Dalaffilla, Erta Ale, eruptions, Ethiopia.
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Just time to note that a new report from Bloomberg quotes an Addis Ababa University researcher as saying that the volcano responsible for Monday’s eruption was Dalla Filla (which the Global Volcanism Program calls Dalaffilla, so that’s the version of the name we will use here).

Also Erik Klemetti has two very useful and up-to-the-minute posts on the Ethiopian eruption at his highly-recommended Eruptions blog: ‘CORRECTED: Erta Ale(?) erupts … and more’, and the more recent ‘More details on the Ethiopian eruption’. Check the comments as well as the posts themselves.

There’ll be more on this intriguing Ethiopian event here later…

The Volcanism Blog

Eruption in Ethiopia – Erta Ale, or not? 6 November 2008

Posted by admin in activity reports, Africa, Erta Ale, eruptions, Ethiopia.
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The identification of Monday’s eruption in Ethiopia with Erta Ale may have been erroneous. An update on the eruption from Dr Simon Carn of Michigan Technological University via the VOLCANO listserv is circumspect:

Satellite instruments detected an eruption in northern Afar, Ethiopia on November 3. The eruption first manifested itself as a large sulfur dioxide (SO2) cloud drifting eastwards over the Arabian peninsula, detected by the Ozone Monitoring Instrument (OMI) and the Atmospheric Infrared Sounder (AIRS). MODIS data from the University of Hawaii’s MODVOLC hot-spot monitoring tool (http://modis.higp.hawaii.edu) confirmed an extensive hot-spot (presumably lava flows) near Alu volcano, in the northern part of the Erta ‘Ale range. Details are still sketchy and these observations are as yet unconfirmed from the ground.

Ethiopian news sources are also rather round-about in identifying the location of the eruption. The official Ethiopian News Agency describes the eruption as occurring ‘at Ertale volcanic area of Afar State, north-east Ethiopia’, while the EthioBlog also speaks of ‘a volcanic explosion in Ethiopia’s remote north-eastern Afar region’.

Wherever the plume came from, it was indeed extensive. The image of the plume below from 5 November, put together from data gathered by the Ozone Monitoring Instrument (OMI) on NASA’s Aura satellite, is from the NOAA’s currently experimental site displaying near real-time 24hr composite OMI SO2 information (thanks to Nickolay Krotkov for this link). The plume stretches across the Arabian Peninsula, the Gulf, and across Pakistan and northern India. The more red, the higher the concentration of sulphur dioxide.

SO2 plume

The Activolcans report on the eruption settles for Alu, on the basis of the SO2 monitoring information from OMI and the hotspot report from the University of Hawaii. More on this eruption as news comes in. Erik Klemetti also has detailed coverage at the Eruptions blog.

News
Volcano erupts in Ertale volcanic area of Afar Region – Ethiopia News Agency, 4 November 2008
Ethiopia volcano sets lava record – EthioBlog, 6 November 2008

Information
Global Volcanism Program: Erta Ale – information about Erta Ale (0201-08=)
Geophysical Observatory – Institute of Geophysics, Space Sciences and Astronomy at Addis Ababa University
L’Erta Alé, volcan actif dans le Danakil – a French page with many pictures of Erta Ale from an expedition to the volcano which took place in November 2006

The Volcanism Blog

Erta Ale eruption reported 5 November 2008

Posted by admin in activity reports, Erta Ale, eruptions, Ethiopia.
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Erta Ale, January 2007 (image by Flickr user filippo_jean, licensed under Creative Commons)

Erta Ale, Ethiopia’s most active volcano and one of the most active in Africa, has been busy with its current low-intensity eruptive phase since around 1967. A basaltic shield volcano, Erta Ale is well known for its remoteness, forbidding environment, and long-lasting lava lake (pictured above). A report today from the African Press Agency, quoting the Institute of Geophysics, Space Sciences and Astronomy at Addis Ababa University, says that a significant eruption took place late yesterday without ‘human or material damage’, but details are scarce. There is a fuller report at the South African business news site Moneybiz (also at the Independent Online) which talks of a 300 sq km lava flow and quotes expert opinion that the eruptions of Erta Ale are due to ‘the expansion of tectonic plates under the Great Rift Valley’. Hmm.

In August 2007 an eruption of Erta Ale caused some fatalities and forced local evacuations. UPDATE: Boris Behncke notes (see comments on this post, below) that this 2007 eruption was not at Erta Ale but at Manda Hararo volcano some distance to the south.

Image: lava lake at Erta Ale volcano, January 2007. Credit: Flickr user filippo_jean. Re-used here under a Creative Commons licence. [source]

News
Afar in Ethiopia rocked by volcano – African Press Agency, 5 November 2008
Record volcanic eruption in Ethiopia – Moneybiz, 5 November 2008
Volcano erupts in Ethiopia – Independent Online, 5 November 2008
Ethiopia volcano sets lava record – BBC News, 5 November 2008

Information
Global Volcanism Program: Erta Ale – information about Erta Ale (0201-08=)
Geophysical Observatory – Institute of Geophysics, Space Sciences and Astronomy at Addis Ababa University
L’Erta Alé, volcan actif dans le Danakil – a French page with many pictures of Erta Ale from an expedition to the volcano which took place in November 2006

The Volcanism Blog