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1999 Expedition

Page history last edited by Frederick Belton 10 years, 4 months ago

In July of 1999 I teamed up with Christoph Weber of Germany and his clients, a German "volcano chaser" (Wolfgang Mueller) and a film crew who were making a documentary for German television.  Celia Nyamweru from St. Lawrence University also joined us for 3 nights in the crater. (Celia is a specialist on the Rift Valley who has been studying Ol Doinyo Lengai since around 1988.)  The German team camped in the crater for 9 nights, and I camped with Paulo, my guide, for 15 nights (July 23-Aug 7).


During the visit, nearly all activity occurred in spatter cone T40.  For the first 9 days it contained a lava lake that became progressively larger and more active.  On the night of July 31 the lava lake filled T40 nearly to overflowing, and powerful degassing created holes in its weak northern rim.  Lava escaped and flowed northeast onto the floor of the main crater. The most interesting activity occurred from Aug 4-5 when a small explosion blew open a vent on the flank of T40 and spectacular lava splashes formed a new spatter cone.  At the moment that eruption began, I was lying in my sleeping bag only about 15m away!  For a few days in early August, T37N1 also contained a lava lake at a depth of around 20m.



We arrived in the crater of Lengai on July 23 and found a small lava lake inside a deep pit in cone T40. During my 15 day stay in the crater, dramatic changes occurred at T40.  The first picture above shows T40 as it was on July 23.  On July 26 its two-pronged summit collapsed into the lava lake.  During the first week of August, bursting lava bubbles formed a dome-like overhang above the lake.  From Aug 4-5 a new spatter cone formed just NW of the main vent.  All of those changes are seen in the second photo, taken on Aug 6.



This snowy looking scene is actually the east crater rim overflow where lava has flowed in previous days or weeks. The lava killed the plants growing on the rim and adhered to their stems but did not incinerate them.



A lava lake existed inside T40 during most of our stay in the crater. Could this be the face of Pele?



Wolfgang and the camera crew observe the lava lake in T40.



This little cone provided the perfect seat for Fred Belton to observe the eruption. In the background at left is the Rim Cone, shown as "C" on maps.



White crystals often form along cracks on the surface of cooling lava flows. Roger Mitchell of Lakehead University has analyzed the crystals and found that they are primarily  natron (hydrated sodium carbonate Na2CO3.10H2O) and aphthitalite - (K,Na)3Na(SO4)2.



The lava lake in T40 gradually became much more active.  Here a bursting lava bubble has just torn away a small piece of a newly formed rim, at left.



Paulo watches a new spatter cone being formed on Aug 5.



The new cone continued to erupt for several hours.



Looking into the vent of the new spatter cone from higher up on the flank of T40.  At this time lava was bubbling about 1 meter down inside this vent.

On the night of August 2 lava suddenly began pouring out of the lava lake and down the east side of  T40.  This time exposed photo was taken about ten meters from the co ne, looking west.



This close-up time exposure of the NE corner of the the T40 lava lake shows the thin ledges that have formed along the sides of the lake.  At upper left is the site of the strongest degassing and spattering which has resulted in a the formation of a hooded secton of the rim.



Time exposure of lava flowing on the east side of T40.



Lava from T40 flowing in an open channel.


Lava flows in an enclosed tube from T40 and emerges into an open channel here.



Lava moves slowly through this channel near the base of T40.



Early on Aug 7 lava was exiting the T40 lava lake via this large channel. Highly fluid lava is visible in the upper section of the channel. The lava was flowing so rapidly that blobs of it were expelled by centrifugal force and struck and burned the material of my trousers,



Wolfgang Mueller is standing at a very dangerous location on the unstable rim of T40 while a lava bubble bursts just below him.



A small lava pond deep inside cone T37N1



Departure of the German team from the summit on Aug 1



Paulo stands near fresh lava below T40.


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