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2003 News

Page history last edited by Frederick Belton 9 years, 5 months ago

 Jan 2003: National Geographic Magazine ran an article about Lengai, with beautiful photographs by Carsten Peter showing activity from the T49 cone group in October 2001.

 

Jan 13, 2003: Johan Smith sent me several aerial photos of Lengai’s crater that he made on this date. No active surface lava flows were visible, but recent grey flows could clearly be distinguished, originating form somewhere in the central crater.  It appears that T58, T57, T56 and possibly other cones may have grown together into one long ridge. T37, T45, T53, T51, T40, T40C, T49B and T49C were clearly visible as distinct cones.

 

Jan 13-14, 2003: Sam Tarnero sent me excellent photos of the crater. Several of his shots showed a cave containing fantastic white soda straw stalactites. According to a diagram he made, the cave was located in the north side of cone T57B. Here is his description of the visit: "We stayed only two days in the crater. The only activity was a big but flat hornito in the middle of the crater with a cave on its side. It was making a sound like a washingmashine. It sounded like there was pretty thick lava inside making huge bubbles as gases escaped. This same cave has a vent right above it, early in the morning we were woken by a very loud noise from exacly that vent. Gases or air where escaping with high pressure, interrupted by loud and intense bursts of what I guess was steam. This activity took only thirty sec. or so.  I didn´t dare climbing the hornito to take a look inside the cave, because I wasnt sure if it would have carried my weight. We had our tent right under the summit wall on the right hand side."

 

Jan 29-Feb 5, 2003:  Yves Bessard and some friends in the Société de Volcanologie–Geneve (SVG) spent 7 nights in the crater (29.01 to 5.02). (Their tents are visible near the East Rim Overflow, in Brian Rippon's Feb 1 photo at the end of this page.) He sent me several photos which show lava effusion from T58's summit and what appears to be a new low vent on the NW flank of T58. His comments on the visit: "Originally our goal was to stay for 5 nights and extend it, if the activity would not have been so great, and it was the case : most of the activity happened on the 3rd and 4th of February. I am currently writing (in French !) an activity report for the March bulletin of SVG. A lot of changes occurred in the centre of the crater, since our last visit on February 3rd to 8th 2002, thus it is relatively difficult to refer to the map of Chris Weber to design the hornitos. The best description would be a "complex" or a "conglomerate" of hornitos. The last big activity occurred probably the night before we went up. When we reached the crater on 29th of Jan. at 9 am the lava flows were still very warm, the photo was taken in the evening when we saw a small lava flow which  lasted only 30 min. There were nice bursts of carbonatite from the central hornito of the complex on 30th of Jan. between 1 to 3 pm. There was a big stream of lava at the base of the hornito (about 6 m long / 2 m wide) on 3rd of Feb. (major activity between 12 and 3 pm). Lava continued to pour out of the hornito without stop until the night of 5th of Feb. Originally we set up our camp on the SW of crater, at the foot of the vertical cliff because it was the only area in the crater without recent lava flow. But, due to the strong wind and the dust we had to find out another place to sleep, so we let there our mess tent and set up our two "sleeping" tents close to the overflow. But, already the next night we were back in our mess tent to sleep even with the wind and the dust ! The reason was the T-37B was rumbling like crazy (and it did during all of our stay) and off course, our tents were exactly in the trajectory of the lava flow if something would have happened... all this story to say that there is no optimal place to sleep inside the crater, I honestly think that, for sleeping (well) it is better to go in the South crater (it takes about 15 min). I forgot to mention that the last day when we waked up, we were amazed to hear a very strange and strong noise. A few minutes later we were back to the central group of hornitos and we got the explanation : an estimated  8x15m of the upper part of the massif had collapsed, it was not possible from the south to approach close enough due to big cracks near to the summit. But from the other side (North) I could go up for a few seconds. There were big waves of lava about 2 to 3 m below and the lava lake seemed to extend much further than the "sky light" of 8x15m, maybe occupying most of the complex (?)"

 

Feb 1, 2003: During a morning fly-over of the crater, Brian Rippon made some excellent photographs which can be seen at  http://www.rippon.net/lengai/index.htm.  What follows here are my own observations of Brian's photos.  "The pictures show an active lava flow originating from T58’s summit area and from a vent lower down on its NW flank. The lava is flowing around the NE side of T49B and T49C toward the NW rim overflow. Little change can be seen, in comparison to my August visit, in the shapes of the T37 cones, T45, T51, T47, T49C, T49B, or T40. A large circular vent is visible in the NE part of T40 and a higher, smaller vent exists just SW of it.  It appears that T57 and T57B have merged into one broad cone, primarily due to growth of T57B. A saddle separates T57B from a ridge to the SW. It appears that the ridge has formed by the merging of T58, T56 and a new cone (with double peaks) that has grown between T58 and T48. (Chris Weber has tentatively designated the new cone as T58B based on a Sept 26, 2002 photo by Celia Nyamweru.) It is clear that the center of activity in the recent past before Feb 1 has been in and around T58. T58 has now completely covered up T52B.  I cannot see T48 or T55; they may have become incorporated into T58 or T58B. T49 also seems to be gone, possibly covered with lava flows from the T58 group.  T40C is still visible but looks low and is surrounded by recent lava flows. In another photo (not shown) I see what might be the low vent opening of T49F at the west base of T49B. It appears to be unchanged from August 2002."

 

Feb 4, 2003:  Richard Wiese of New York City's Explorers Club climbed Lengai. "I started at approximately 1 AM, reaching just below the summit at 5AM. Waited with a Massai guide till sunrise to go onto the actual summit. The day before I had observed some major exhalations so did not want to walk around in the dark. During my 1 hour stay on the crater I did see lava shooting from the largest hornito (?) about 20-30 feet into the air with a periodicity of around 1-3 minutes. Saw smaller flows in the crater as well"

 

Feb 5, 2003: Friedemann Vetter flew over the crater at 9:25 EAT. His photo, seen below, clearly shows the collapsed area of T58. The collapse, described above by Yves Bessard, had occurred earlier that morning.Lava flows from T58 have reached the north crater rim wall.

 

Photo courtesy Friedemann Vetter


June 9, 2003:  Donald A. McFarlane reports: My colleague and I just returned from a visit to Lengai; on the summit the morning of June 9th. Activity was modest; with one "splatter cone" throwing small amounts of material perhaps 2-3 m into the air.  As cave scientists, we were most interested to note an opening into one of the hornitos, exposing a significant cave with sodium carbonate spelothems.

 

Mid June, 2003:  Johan Smith flew over the crater and made the photograph below, which seems to show a lava lake in the small "caldera" containing T58B and the crater of T56. It is not possible to tell if the black area is really liquid lava or just a fresh solid coating the inside of the "caldera."  It appears that there may be a black cone present inside the "caldera", could it be T58B?  There is no sign of any recent lava flow on the crater floor, except possibly at the NE edge of the "caldera."  The photo also shows an open black vent at the site of T49.  This may be a new cone that has formed on the site of the original T49. There is no sign of T56B, which is first described in the next report by Chris Weber.

 


Photo courtesy Johan Smith


June 29 - July 3, 2003:  A visit by Chris Weber of Volcano Expeditions International revealed that "since the report from Bernhard Donth and others by visits Febuary 2003, most activity had occurred in the center part of the crater. Lava flows and hornitos out of the center part were strongly weathered. C. Weber noticed a new formed hornito NW of T56 and because of an open connection to T56 this hornito could be numbered as T56B. Lava penetrated once through the underground from T56B into T56. This T56B was on 29 June a collapsed hornito located at the north end and inside (integrated) of the huge T58B, T58 pont. This pre June hornito T56B erupted with strombolian type activity during the visit of C.Weber. Observations by Burra Gadiye established this kind of eruptions of T56B also some days before 29 June. Only in averege the following facts discribe the activity of T56B. One third of the time of observations, a lava lake inside T56B spattered in common kinds with a strong, but non explosive release of gas. Another third of the time of observation the lava lake seemed calm (forced back or secluded), but a huge quantity of gas released outside the hornito T56B, simular in sound and power like a Boing 747jet engine on full trust. The period of this events lasted from 1 to 2 hours. Another third of the time strombolian eruptions accoured with very explosive lava spattering  more than 40 meters in altitude. The strombolian intervals were between one and 30 seconds. The period of this events lasted from 10 minutes to 2 hours. Fumarol temperatures at the NW rim overflow were 86 degrees celsius and inside a fracture at the base of T49C about 76 degrees celsius."

 

July 13 - July 18, 2003:  Paul Hloben reports: "I stayed on Lengai for 6 days (13-18 July 2003). The volcano was erupting all the time what can be best described as Strombolian activity - magma was ejected by gases in discrete bursts resulting in showers of lava fragments up to 25 cm in size normally 3 to 20 metres high collecting on the flanks of the cone. The individual bursts occurred in 2 to 5 second intervals. The eruption usually lasted between 8 to 15 minutes following the equal time of rest. At times, spectacular jet-like explosions (see the attached picture) sent blobs and a poor ash cloud up to 50 metres high (if not more), showering the crater floor with small (up to 5cm) blobs and up to 30 metres from the cone. Ash fell sometimes outside the crater, blown away by strong winds.  This activity was usually longer lasting (between 15 to 25 minutes) with powerful bursts every 1 to 3 seconds. This activity occurred from a new cone (the black cone in the attached picture) that has grown up from 6 to 8 metres in two days (13 to 15 July). The other, white cone in the foreground was also active.  It was completely roofed, with a lateral opening 1m x 0.5m (not visible in the picture) about one metre below its rounded top. The activity usually not coincided with the black cone. It was bursting lava blobs up to 5 metres high after 2 to 3 puffs of steam (like a locomotive).  Occasionally strong bursts sent lava  fragments up to 15 metres high.  The black cone was positioned (exactly between T49 and T56 on your map) on  the NE side (outside) of the huge collapsed T58 cone (this is my assumption because T58 had a different position than that on your map from August 2002,  but very similar to Brian Rippon and Friedemann Vetter pictures. It was elongated from NE to SW - not N to S as on your map.  The T58 dimensions were max 20m x 10m, it looked like a huge swimming pool with a metre wide terrace around its perimeter marking the original level of lava. From there a drop of about 1.5 metre marked how much lava drained during the collapse (at least 300 cu metres?). The white active cone was situated on the SW side within the collapsed cone (see the pic). The two active cones were about 15 metres apart. On 15 July at 23h30 I was waken up by a strong noise. Sleeping on the crater floor between T26 and the SE crater rim I was obviously worried about lava flows as this was the lowest point on the crater floor, but the furthest point from the erupting cones. I immediately ran out of the tent. The cones were not showing any incandescent eruption.  The rumbling within the black cone was very loud with violent sounds.  After about 10 minutes of staring at the site, all hell broke loose and a spectacular eruption started, putting Stromboli to shame.  I grabbed my camera and ran uphill. I stopped next to T37B, about 70 metres from the eruptive site.  Loud explosions every second or so send huge lava bursts tens of metres high.  The cone was permanently red from falling pyroclastics.  It looked like the Etna 2001 flank eruption. After 20 minutes the eruption ceased and I came within 10 metres to observe the site.  At least 2 metres of the cone collapsed into he crater, causing the event (probably).  Hardly 5 minutes passed and the eruption recommenced with the equal fury. I stayed till 3h30 observing many of this spectacularly-violent eruptions. Since then the white cone stopped erupting. The following day (16 July) I observed many big eruptions, though not as big as those at the night. On 17 and 18 July the cone calmed to its 15 July pre-collapse activity.  No lava flows were observed during my stay. On 18 July the cone had grown up 3 metres from its 15 July collapse, reaching about 9 metres in height. You can check the images on http://volcano.20m.com click on Lengai Photo. When we were driving from the Waterfall camp towards Lengai at 15h00, to our surprise, we saw jet-ash eruptions from the bottom of the Rift Valley."

 

Aug 1 - Aug 8, 2003: (For photos see 2003 Expedition) Fred Belton, Marco Fulle, Stefano Granier, Tom Pfeiffer, and Martin Reitze, accompanied by Paul Mongi and Othman Swalehe, observed that recent and ongoing activity was confined to a small area of the central crater that contained the active cone T56B.  Another active cone, T58B, was positioned inside a small caldera adjacent to T56B. On Aug 1, T56B was a black cone ~12m in height, its lower two-thirds composed of fresh loose scoria and its steeper upper third composed of fresh spatter.  The caldera was a roughly oval structure about 45m long, oriented from NE to SW.  It had a distinct rim 2-3m high on the south, west and east but its northern rim had been buried by scoria from T56B. Several small channels on the rim showed where lava had overflowed from the caldera in previous eruptions.   Cones T39, T46, T37C, T52, T52B, T40C, T55, T56, and T58 were no longer visible. (The NE end of the caldera had contained the active vent of T56 during Chris Weber’s visit from 29 June – 3 July.)  T49, a heavily weathered spatter cone one year earlier, had disappeared by Feb 2003 but eventually formed again in the same location.  Now a cinder cone, it has been partially covered by the growing flank of T56B. T48 was barely distinguishable and appeared only as a lump at the W end of the caldera. T40 was drastically reduced in height by lava inundation from the caldera and honeycombed with unstable arches and caves.

 

From the summit of Lengai, many old brown lava flows originating from the caldera and older central crater vents could be distinguished. They have dramatically changed the topography of the crater by covering up many old cones and further increasing the height of the crater floor.  In comparison to Aug 2002, The NW rim overflow width appeared unchanged, the E rim overflow grew by 5 m to 44m and the W overflow grew by 5 m to 17m.

 

All activity occurred from T56B (first described by Weber on 3 July 03) and T58B.  At  0930 on 1 Aug T56B was ejecting spatter up to 20m as a result of Strombolian activity, with 30 minute long active periods followed by 10 minutes of repose.  Activity declined in the afternoon and was low until the afternoon of Aug 2, when stronger eruptions ejected solid and partly liquid material 3-15m above the cone. At 0040 Aug 3 the upper 5 m of T56B collapsed silently. Twenty seconds later an episode of strong activity began, with bombs falling within a 25m radius of the vent.   On 3 Aug Strombolian eruptions at T56B ejected bombs to 50m and ash to 100m. Explosions were audible in the south crater at times.  After 1320 activity stopped. On 4 Aug T56B’s ash and bomb eruptions resumed and T58B began to eject spatter.  Around 1630, T58B began to steam heavily from several locations, in particular from a vertical crack in its S flank.  Steaming intensified and the cone abruptly collapsed.  After collapsing a 15min eruption of T58B ejected bombs and blocks to 40m.  During the evening there were Strombolian eruptions from both T56B and T58B.  By 5 Aug T56B had been rebuilt to a sharp cone and both active cones were erupting weak ash puffs and a few bombs.   At 1900 the upper 3 or 4 meters of T56B collapsed.  The collapse began with a landslip on the N side of the cone, followed by disintegration of the E side.  The west side of the cone remained standing. Immediately after the collapse, violent spattering and overflows covered much of the cone with glowing lava.  Similar eruptions continued, separated by pauses of ~5 min between them. During the third eruption the remaining west side of the upper cone collapsed.  Strong ash eruptions followed later in the evening.  By 6 Aug T56B had once again rebuilt itself into a steep cone. During the day and evening activity was very low, but there was a strong smell of sulfur in the area just south of T56B.  At around 0400 on 7 Aug short lava flows from T58B and from a hole near T58B’s base entered the caldera. Spatter up to 10m from the hole rapidly built a new cone on the NW flank of T58B.   A lava pond formed in the new vent and bursting lava bubbles erupted to 15m. By mid morning the new vent merged with the original T58B vent, forming a single long, narrow summit vent.  Activity at T58B ended by noon, and T56B had begun to turn white due to its very low activity. No further significant activity occurred before our departure at 0730 on 8 Aug.

 

 

Sept 10, 2003: Gaston Gonnet reported minor activity at T56B, T49, and T58B.  Gaston's photo (below) shows that T49 has become active again, after having been mostly buried by T56B's growing flank.  T56B is the tallest cone in the photo, with the jagged peak of T49B just left of it.  T49 is the dark black slope between the two cones.  T49 had been mostly buried by the flank of T56B when it became active again, so now it appears (see Charlie Grieves-Cook's photo below) to be growing from the flank of T56B.  Evidently T49 ejected quite a lot of fresh lava shortly before Gaston's visit.  Since there appear to be no lava flows from T49, the activity was probably Strombolian. The cone immediately right of T56B is T58B which has grown much larger since Aug 8.  To see more photos of Gaston's climb, visit his website.

 


Photo courtesy Gaston Gonnet


Sept 13, 2003:  Duncan Drury climbed and witnessed activity from T56B and T58B. Photos on Duncan's website also show that T58B has grown much larger than it was on Aug 8.

 

Sept 13, 2003: Charlie Grieves-Cook visited the crater and made a picture from the summit. I have cropped the photo to show the central crater only. It appears that since Aug 8 there have been no visible lava flows on the crater floor. T58B has grown considerably and has covered the SW rim of the little caldera that contains it. T49, nearly buried by T56B, has resumed activity and is clearly seen in the photo above, attached to the W flank of T56B (the tallest cone in the crater.)   While Charlie was there, T58B and T56B were erupting lava and T49 was degassing. To see more of Charlie's Africa photos, visit Images of Kenya. 


 

 

 

 

 

 

 

Photo courtesy Charlie Grieves-Cook

 

Sept 2003: Joerg Keller wrote the following interim report covering his recent visit to Lengai : "We camped at the summit from Sept. 27th to October 1st, and picked up at the summit our colleagues on the 5th.  Jurgis Klaudius and two more students from Freiburg have been one day up earlier in September, thus between Fred's visit and our summit camp.  All activity was at the group of T56n-T58n, as I understand your numbering.  In summary, it seems that for the whole of September T56"B" had magnificent lava splashing and gas jets producing ashes. The eruptions were nicely seen from the rift floor. When we arrived on Sept. 27th it had some sort of double peak, always collapsing and rebuilding in the summit part. On 27th to 28th some short lava flows were emitted, in part spatter-fed. Next to this 56 group T58? (wait for GPS!) collapsed and showed a nice "hornito-caldera" with obviously a lava lake inside. The walls were too fragile to go to the rim.  Over the period of observation, the strombolian activity continuously decreased in intensity, calming down at the end to more sporadic gas bursts and some spitting and splashing. But always lava remained present in the three throats, such is the 56-double peak and the presumed 58.

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