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2002 News

Page history last edited by Frederick Belton 9 years, 8 months ago

Jan 2002: Ronald Hanson reported: Although January is not a bad time to do Kili (although I think Aug-Oct is probably better), it's not nearly as good a time to climb Lengai.  The rainy season there started shortly before we arrived making the road to Lake Natron almost impassible.   When we got to the crater rim it was cold (about 10 - 15 C.), windy and  rainy.  We could only see about 20 to 40 meters.  It could have been worse, there had been a thunderstorm at Lake Natron just hours before we  started our climb. However, we did see one large (4 - 5 meters diameter) active, boiling lava pool.  I was quite surprised to see how "foamy" the lava  was.   There were also several very recent lava flows (our guide said  less than two days old) one of which provided us with some much appreciated warmth.  Even these flows were light brown to white.  The rest of the crater floor was covered with a thick layer of light brown powder.

 

Aug 2002: During 4-9 August 2002, (for photos see 2002 Expedition) Fred Belton, Sven Dahlgren, Jeff Brown, and seven others observed four new spatter cones that had formed between 22 June and 4 August. One of these new cones was T55. Inactive when visited, T55 formed a white cone under 2 m tall containing a wide crater. T56, black and active, was ~7 m tall including a distinctive thin spire rising ~2 m above the summit. T57, ~4 m tall, was partly black but inactive. T57B stood ~7 m tall and was covered by fresh black lava. T54, documented by Weber on 21 June, had disappeared. Older cones such as T37B, T49B, and T49C had grown significantly since 2001 and towered above the N half of the crater rim.  Throughout the visit, T57B ejected clots of lava, expelled loud gas puffs, and produced thick clinkery aa flows. T56 spattered intermittently, T48 erupted pahoehoe lava from vents near its NW base, and T44 and T46 also produced spatter and a few short flows.  At around noon on 4 August a new vent, T49F, abruptly opened in rough, steaming ground near the W base of T49B. The eruption began with noisy ejection of spherical lapilli to a height of ~7 m and fluid lava to a height of 1 m. Throughout the day, the vent erupted at intervals of 1-2 hours, ejecting clouds of lapilli and forming aa lava flows that moved slowly W and NW to the crater rim area. Around 0200 on 5 August T49F eruptions dramatically increased in height and volume. Fountains played to at least 15 m and produced a flood of fluid pahoehoe that flowed W with great speed, destroying a supply camp. (See 2002 Expedition Accident: Lava in the Kitchen.) Similar eruptions continued for the next 28 hours, at first about two hours apart with gradually lengthening periods of repose between eruptions.  A typical T49F eruption consisted of lava first flowing or spattering from the low, open vent, then the abrupt onset of violent fountains that played for 2-4 minutes to a height of 10-15 m at a ~60° angle toward the W, and finally a decrease in fountain height and the draining of lava back into the vent. The final draining accompanied loud noises that to J. Brown sounded like "sheet metal being bent." By the afternoon of 5 August the site of the supply camp was under at least 1 m of thick pahoehoe slabs. The area just W of the vent was more than ankle deep in 2-8-mm-diameter spherical lapilli. Three vigorous fountaining episodes at T49F the night of 5 August started brush fires along the W crater rim. After dawn on 6 August, T49F's activity gradually waned, completely stopping by evening.  On 7 and 8 August T49F was completely inactive, thin pahoehoe lava flowed from T48, and T57B produced meter-thick clinkery aa flows. In the central crater there was an exceptionally strong smell of sulfur that at times made breathing uncomfortable, continuous low-pitched audible vibrations, and frequent hard bumps and tremors underfoot, especially near T57B and T56.  At about 2300 on 8 August a fissure ~12 m in length opened between T52B and T56 and began erupting a curtain of fire 6-8 m high with nearly continuous violent explosions. After midnight observers began to see an elongated spatter cone containing an extremely vigorous lava lake, whose surface rose ~0.3 m/hour. The new cone (T58) gradually merged with the flanks of T52B and T56. By 0830, T58 was over 2 m tall and its lava lake measured ~5 x 9 m. Lava bubbles over 2 m in diameter burst every 1-3 seconds and the activity showed no sign of abating when observers left at 0830 on 9 August. A photo from 17 August by Jean Bahr documented that T58 had grown to ~10 m in height and had a wide circular summit vent.

 

 

Oct 2002: Paramount Pictures shot footage for the film “Tomb Raiders II” in the crater of Lengai, using helicopters for access.  Unfortunately the footage shot in the crater was very brief. One scene showed Lara Croft (Angelina Jolie) climbing out of a vent in the crater floor. I am pretty certain that vent was T49F, which destroyed the "Kitchen" in Aug 2002.

 

Dec 29-30, 2002: The following report was sent to me by Claude Grandpey, President of L'Association Volcanologique Européenne (L.A.V.E.).  “I visited Ol Doinyo Lengai on December 29th and 30th during a trip organised by the French agency Aventure et Volcans. We left our camp at Engare Sero in the early morning and arrived on the crater rim at 11 o’clock or so. The first thing we saw was a very active lava lake in T49, that began to overflow a few minutes after our arrival.  The consequent lava flow was about 10 to 15 meters wide and reached a length of about 50 meters before stopping [See picture]. Indeed, as the overflow stopped after a few minutes, the flow itself was no longer fed and could not progress. I measured the temperature inside the solid flow some 2 hours after it had stopped.  The lava was still quite hot with 462°. However, the lake – which had a roughly circular shape and was about 5 meters in diameter – was extremely active and noisily throwing up and around blobs of fluid lava. This type of activity lasted all through the day, without any other flow to be seen. After several hours of careful observations, I decided to climb the cone and stand a few meters from the lake.  It looked as if it was fed in a oblique way from a vent on its south-western side; then the lava would come under pressure against the eastern inner side, before being projected back to the west and splashing out. Standing a few meters away from the lake was very impressive. One could feel the pressure of the lava as it splashed against the eastern side and the whole cone was vibrating under the feet! It has to be noticed that in the evening the activity decreased at the lake itself, and a small vent opened a few meters to the east, emitting occasional vertical squirts of lava. By that time, atmospheric pressure had gone down by 10Hp and it confirmed observations I made on other volcanoes, indicating a link between moderate eruptive activity and atmospheric pressure. All the time we stayed in the crater, cone T40 kept roaring, but no lava ever came out of it. After a night of heavy rain, we visited the crater one more time. No lava flow had occurred during the night. Another lake was still bubbling at T49, at the exact spot were lava was squirting vertically the day before. It was violently throwing blobs of lava on its outer slopes. After watching the event for some time, we left the crater.”

 

 

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