This was a special year on Lengai!  One hundred years after the first brief scientific observations by Prof. Fritz Jaeger in 1904, the eight members of the 2004 expedition experienced some extraordinary activity during their week at the crater, and I remained there another 23 nights to gather data that will be used in an attempt to determine if the timing of eruptions is influenced by the lunar cycle or by changes in barometric pressure.     

The expedition began rather badly with two days of terrible weather and very little activity, followed by a very dangerous situation at T56B which could have easily led to loss of life. After that the weather improved and the activity followed suit, with beautiful eruptions from T58B and T49G. On 4 July there was so much interesting activity that people had trouble deciding which eruption to watch. After the first week the expedition members left but I remained at the crater alone to collect additional data. On 15 July I had the privilege of seeing an amazing paroxysm that was a bit frightening in its strength.  A newly opened vent, T58C, ejected gas, ash and lava high into the air and sent several raging rivers of lava through the eastern half of the crater.  I unofficially named the vent "Charging Rhino". On the last two nights a leopard visited the camp.  For more detail about the activity, see 2004 News.

Members of the 2004 expedition were Ge Beijers, Thorsten Bockel, Jeff Brown, Fabian Cruchon, Olivier Gruenwald, Patrick Koster, Martin Rietze, and Richard Roscoe.

 

 

En route to Lengai, Thorsten meets some Masaai boys.

 

 

Expedition base camp in Engare Sero village

 

 

These bags of food and cooking gear were carried up Lengai by Masaai porters.

 

 

Richard models the latest "hot" styles on Lengai: safety glasses and a jacket with lava burn holes. He was hit by spatter from an eruption of T58B.

 

 

Thorsten and Richard photograph inside the "hornito cave" of T45.  This cave existed in July 2003 but at that time was too deep to enter and was full of steam.  Inside this cave we found a vertical shaft leading up to the cone's summit vent. Entering the cave was dangerous due to the possibility of rockfall or collapse.  On July 15, 2004, the entrance was obliterated by huge lava flows from the birth of T58C vent.

 

 

Interior of the T45 cave. The cave floor is composed of lava flows that entered through the cave entrance, probably from T56B.

 

 

This raven and its mate were the "terrorists" of Lengai. They tore open luggage and bags of garbage and made a mess of any gear that was not wrapped in strong woven plastic bags. Fortunately they did not tear up the tents. One of them dropped a stone on Jeff Brown while he was eating lunch and broke his plate. This photo is by expedition member Patrick Koster.

 

 

This is T58B, the most consistently active cone during July. It produced a great deal of Strombolian activity and many lava flows. The tallest vent of the cone, at right, ejected spatter only a few times, but frequently emitted puffs of gas.

 

 

View of T58b after a series of lava flows.

 

 

Ge stands in front of the breached cone T56B, which was nicknamed "Little Etna" in 2003. Inside the cone was a large lava platform that collapsed into a huge underlying lava lake. Ge was one of the last people to walk across the platform before it collapsed.

 

 

Kilimanjaro seen at dawn from T56B in the north crater of Lengai.

 

 

Expedition members photograph lava flows from T49G on 4 July.

 

 

At about 1500 on 15 July a small hole near the base of T58B began to emit gas and spatter.  A large fountain quickly developed and lava flooded the east part of the crater. I unofficially named this vent "Charging Rhino". The official designation of this new vent is T58C.  The cone in the background is T45. 

 

 

This time exposure shows the location of the new T58C vent. At this moment the vent is in a state of repose between eruptions. The breached cone behind the vent is T56B.

 

 

A distant lightening flash lights the sky as flash floods of lava from the new vent T58C flow south toward the crater wall below the summit and also east (not visible here) to the east crater rim and down the flank of the mountain. This time exposure captures reflections of the lava on several cones, including T47 (left of center) T56B, T57, and T37B. The dark cone outlined against the lava is T37. Slight strombolian activity is also seen in the crater of T56B. The time exposure makes the lava appear brighter than it actually is.

 

 

This is one of the lava flows that formed as a result of the 15 July eruption of T58C. The cone on the left is T45.

 

 

This view from the summit shows the extent of the flows from the T58C eruption on 15 July.  All of the dark lava flowed through the crater from about 1530 to 2030. Lava extended to the right (east) and flowed across the east rim overflow and down the flank of Lengai.

 

 

The momentum of the lava from T58C caused it to flow nearly 3m (10ft) up the west side of T45. The entrance to the cave in the north side of T45 could no longer be seen. It would have been very difficult for a person too close to this eruption to escape from the lava.

 

 

The lava burned vegetation and set a brush fire as it crossed the east crater rim.

 

 

Lava flooding toward the east rim overflow from T58C formed layers of "shelly pahoehoe".  At this location an underlying obstruction caused the formation of a rough area in the flow.

 

 

This is the new T58C vent as it was on the morning of 16 July. Lava was bubbling inside at a depth of about 2 meters. The cone in the left background is T45. View is toward the east.

 

 

Lava simmers inside T58C in the early morning.

 

 

Spattering and overflowing lava gradually built up a rim around the lava pond in T58C.

 

 

Continued spattering of T58C over the next few days built a taller cone.

 

 

On 23 July a new sub vent of T58B formed when a section of vibrating ground gave way.  Prior to the eruption the ground at this location moved up and down rapidly like a diaphragm undergoing rapid pressure changes.  This vent spattered strongly and eventually produced a lava flow that extended most of the way to the southern wall of the crater, near T30.

 

 

 

We found these leopard prints next to the tents on July 28, and that night heard the leopard coughing as it watched us. Photo courtesy Celia Nyamweru.

 

 

This natural arch formed in the top of T58B as the result of explosive activity on 21 July.

 

 

The extinct volcano Kerimasi, with Lengai's inactive south crater in the foreground.

 

 

Late afternoon shadow of Lengai on the Rift Valley floor.

 

 

Lava from an eruption of T49B flows toward the NW overflow on 26 July, 2004.

 

 

In Engare Sero on 29 July. Celia, myself, Lois and Sue with porters, our driver Akyoo and porter Danielli kneel at left. Photo by my wife Debby.