Activity: 2006-2007

By early 2006 the summit crater was almost full; it looked very like the ‘platform’ that the early German explorers had described from 1904 and 1910. The photograph below was taken by Guido Simonetti on 23 March 2006.

Over the months that followed, changes took place in the cones standing towards the center of the platform, and considerable amounts of lava flowed over the crater rim and down its outer slopes. The first photograph below (left) was taken by Anne Dijkman flying to the north of the summit in September 2006, and shows a wide overflow down the western slope of the volcano. The second one (right) is from the following year, probably in July or August 2007, and was taken by Meave Leakey. This shows a wide overflow down the eastern slope, whose lava is already white, contrasting with the dark burned vegetation on the rest of the slope. There are fresh black lava flows that have originated from vents close to the pointed cone in the center of the summit crater.

On 30 March 2006 some quite powerful activity began in the summit crater, which led to the movement of people from nearby villages, and to news headings and stories such as “Villagers flee as volcano erupts” (IPP Media 1 April 2006) and “The only active volcano in Tanzania burst into flames … at least six villages occupied mostly by nomadic Maasai herdsmen were rocked by red-hot landslide, spewing scalding fumes and lava covering a big area on the mountain slopes” (AfricaNews 26 April 2006). However these stories were quite exaggerated, though certainly lava did reach much further than it had since overflow from the crater rim began in 1998; estimates are that one flow down the west side of the mountain may have traveled as far as 3 kilometres from the summit, reaching close to a Maasai homestead.The photograph below, by Michael Dalton-Smith, was taken on 30 March 2006 and shows fresh black lava extending a long way down the outer western slopes.

In July 2007 earthquakes originating close to Oldoinyo Lengai were felt widely, some as far away as Arusha and even Nairobi. The tremors in Nairobi were so strong that people rushed out of office buildings in the central building district. A BBC news story on 18 July described how “Dozens of workers declined to enter high buildings … worried about their safety”. At least six tremors were reported between 12 and 16 July, with magnitudes ranging from 4.4 to 5.4. The epicenters of the earthquakes were located at a depth of about 10 kilometers (that is, relatively shallow depths) mostly below Lake Natron and close to Mount Gelai on the eastern edge of the Rift Valley.

Relatively small scale activity continued in the summit crater for several more weeks: Chris Weber’s photograph below, taken on 23 August 2007 shows the topography of the summit area essentially unchanged from earlier months, with cones rising from the central area of the platform surface, and fresh lava flows radiating towards the edges of the platform.

Satellite observations detected thermal anomalies (that is, unusually hot conditions) at the summit area between 23 August and 3 September, and again between 10 and 20 September 2007.

On 3 September 2007 a large ash eruption began, creating clouds of ash 3 to 4 km high. The photograph below (left) was provided to me by Thad Peterson. A more detailed view of the early stages in this eruption comes from this photograph (right) by Gwynne Morson, taken on 6 September 2007.

Eruptive activity continued into early 2008; see the Recent Activity page!

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