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Lengai Hazards

Page history last edited by Frederick Belton 9 years, 4 months ago

Much of the information given below is not currently applicable to Lengai due to the changes brought about by the 2007- 2008 explosive eruption. The active vents are deep inside the summit crater and are no longer accessible to climbers. Currently the main dangers are the potential instability of the crater rim, the risk of sudden unexpected explosive activity, and the steep, unstable terrain during the ascent and descent. When the pit crater eventually fills with lava and becomes accessible to visitors the safety information below will again be relevant.

 

The late Katia Kraft, one of the world's most experienced "volcano chasers," once described Ol Doinyo Lengai as a "toy volcano." In one sense she was right, because the small cones inside the crater often seem to produce harmless miniature eruptions and cute little spatters of lava.  Even the lava is not very hot compared to other volcanoes in the world.  In spite of that, the crater is very dangerous.  People observing an eruption at close range are at very high risk for minor accidents and at moderate risk for serious accidents.  In fact, Lengai may be the world's most dangerous lava-erupting volcano in terms of risk to crater visitors.  That is because the low lava temperature and the small size of the intracrater cones encourages photographers and other observers to approach much more closely to the eruptions than they would at basaltic volcanoes.  In such close proximity to a vent it is easy to be overtaken by unexpected changes in activity, which often occur much faster at Lengai than at other volcanoes.  The highly fluid natrocarbonatite lava can flow rapidly and sometimes bursts from vents without warning.  The intracrater cones of Lengai are structurally weak and collapse often. I count myself lucky to have not been seriously injured or killed on Lengai, considering that I have spent more than 3 months in the crater and had a close call of some sort on nearly every visit.

 

There have been some serious accidents on Lengai. In 2000 a camper sustained a third degree burn to his foot that required skin grafts.  In 2002 lava destroyed part of an expedition camp and burned a guide. In 2007 a porter fell into flowing lava and received severe burns that led to the amputation of his legs.

 

Here are some example of what can happen and some suggestions on how to stay reasonably safe:

 

1. Be cautious around fissures and cracks. I saw a very experienced volcano climber fall into a crater rim fissure because he was pulled off balance by his heavy backpack. He became pinned under his pack and could not climb out without assistance. The crater rim may also be unstable (See 10 below).  Sections of the crater rim may collapse into the deep pit crater formed by the 2007-2008 explosive eruption. In July 2000 one of my legs plunged up to the hip into a hidden cavity inside the crater rim.  

 

2. The cones on the crater floor can collapse under you if you climb on them. In 1998 the flank of a cone collapsed under me and I fell waist deep into a steaming hole. At the base of the same cone a few days later, one of my legs plunged hip deep into the soft flank just as a fast moving, very fluid lava flow was bearing down on me. By the time I extricated my leg the lava was only a couple of feet away and closing fast.  I avoided serious burns with about one second to spare. In a third incident, the flank of a cone collapsed into a deep pit less than 12 hours after a woman and I climbed on it, revealing that a large section of the flank we walked on had been only about 5 cm thick.  Finally,  in 2004, a flat lava platform of around 300 square feet (~35 square meters) inside T56B collapsed about 40 minutes after some expedition members and myself had walked across it.  After the collapse we could see that the platform was only a few cm thick and had been covering a huge lava lake.  Even a part of the lava platform that we believed to be safe had collapsed.  That was one of my closest brushes with death in all my experience on Lengai.  The next day, part of the rim of the same cone collapsed just after an expedition member had stood on it.  His footprints could be seen leading to the vanished section of rim, which fell into the lava lake.  I believe that the number one safety rule for Lengai should be: Do not climb on the cones!!

 

3. Cones can collapse on top of you.  In 1999 the summit area of a large cone containing a lava lake collapsed less than 3 minutes after I left its rim. The section of the cone's rim where I had been standing was struck by large boulders and then broke off and fell into the lava lake. Cones that are already partially collapsed and have overhanging sections are the most dangerous.  Do not go inside a partially collapsed cone.

 

4. Lava spattering out of lakes, from the tops of cones, and from lava channels can burn you because it is around 950 degrees Fahrenheit (510 degrees Celsius). That is a major risk since it is very tempting to get close to activity for photographs. I have received several dozen small burns from tiny blobs of spatter.  In July 1999 I was struck in the face with great force by spatter from a bursting lava bubble in a lava lake. The lava adhered to my face, giving me several second degree burns above and below my right eye, and leaving me with a scar. My sunglasses saved me from a serious eye injury. The lava melted two small parts of the glasses, one location being INSIDE the lens. Always wear glasses when you are anywhere near activity, and if approaching closely to violent activity wear safety glasses designed for chemical spills. (Those protected me very effectively in 2000.)  In July 2001 an expedition member not wearing glasses was hit in one eye by spatter from a lava channel.  He was incredibly lucky because his eye was closed at that instant.  He received second-degree burns on his upper and lower eyelid and I had to remove some solidified lava particles from his eye.Stay away from places where you can see spatter landing and accumulating. Wear as much clothing as possible, including long sleeves, long pants, and a hat. A thick wool sweater provides especially good protection. If a lot of lava splashes into the air and you think some of it may hit you, turn your face away immediately.  If the lava hits you, much of its heat will be absorbed by your clothes if they are thick, but they might start burning.  That assumes that the amount of lava involved is quite small.  Contact with more than a few "spoonfuls" of lava would be a major accident and would cause serious, scar producing burns. Being "drenched" by a large volume would probably be fatal.  Lava also damages equipment, as I discovered when it melted a hole in my camera.

 

5. If you walk around in an area of lava that is flowing on the crater floor, (it will be black during the day and dull orange at night) be sure to test your footing before you put all your weight on a flow. If the lava is moving, it will definitely not support your weight, except in the case of certain thick aa flows.  At night, a flow that is glowing orange will not support your weight.  Even lava that is not moving and not glowing orange may be liquid inside, and that is the most dangerous kind.  There have been several people, including myself, who have stepped into lava but were not injured due to the protection offered by leather hiking boots.  It is essential to wear leather hiking boots in the crater.  In October 2000 a person wearing plastic shoes stepped into liquid lava. One boot melted and caused third degree burns on his foot and ankle. After being carried most of the way down the mountain by porters, he returned to his home country for skin grafts.  The value of leather boots was demonstrated on my 2001 expedition when a member wearing them stepped into ankle-deep lava with both feet while trying to cross a wide flow. His shoelaces burned completely and his blue jeans ignited but he able to extinguish them with water and was not burned at all.

 

 

Boot and foot of October 2000 accident victim.

Wear all-leather boots so this will not happen

to you! Photo Copyright Daniela Szczepanski.

 

6. I heard of an occasion when a previously inactive cone suddenly exploded without warning, throwing some large rocks several meters away from its flank. That is probably a rare event, but it indicates that no place in the crater is safe from sudden violent activity. In 2002, sudden violent fountaining episodes began from two locations in the crater floor during a 5 day period.  People had walked over or near those locations just an hour or two before the eruptions began.  Cones and the rims of lava lakes have also been known to collapse suddenly and release a flood of fast moving lava that could overtake an unprepared person. That happened in July 2001, causing an expedition member to have to run to avoid the flood.  A lava flash flood can flow faster than a person can run.  On July 23, 2000 a cone suddenly erupted a high and voluminous lava fountain that would have probably killed anyone standing just NW of its base.

 

7. Camping on the crater floor has become extremely dangerous.  In August 2002 a violently erupting vent flooded the W part of the crater floor with fast flowing pahoehoe lava.  Our supply camp was destroyed and on the second night we had to stand watch for lava flows.  Large fluid pahoehoe flows can travel from the central part of the crater to the rim in well under one minute. For details of our mishap, see 2002 Expedition Accident: Lava in the Kitchen.  There are a few places on the crater rim where a small bivouac tent could be erected, but the safest option is to set up camp in the inactive south crater.  Any groups camping on the crater floor should keep a 24 hour watch.

 

8. There are sometimes caves and lava tunnels that are large enough to explore, but they might contain a high concentration of carbon dioxide.  Caves could also become active and rapidly fill with lava.  Pieces of the cave ceiling might fall on your head. 

 

9. Ol Doinyo Lengai has a history of occasional explosive eruptions. If any large explosions occur while you are in the crater, survival would be a matter of luck.  The most recent big eruptions were some relatively small ash explosions in 1993 and  very major explosions in 1966 that blasted out a deep pit crater.  Judging by eruption frequency over the past hundred years, Lengai is about due for another big blow up.  

 

10. There is evidence that the overall structure of the crater is weakening.  For years some scientists have been predicting a collapse of the crater wall due to pressure building against it from lava filling up the crater.  Large cracks in the rim and crater floor have been more apparent in the past three years, and in 2001 a lava flow that passed completely through a fissure to the E flank proved that the cracks permeate the crater’s overall structure.  Obviously a major landslide would be disastrous for those on the slopes or in the wrong part of the crater.  As of 2011, it appears that the most unstable part of the crater rim is the NE quarter.

 

11. There is always a possibility of falling during the steep climb or descent.  In 2001 I fell on a relatively easy part of the descent and hurt my knee to the point that the remainder of the descent was painful and slow.  One of my clients had a bad fall on the lower slopes in 2003.  There is also a problem with falling rocks dislodged by other climbers, a considerable hazard on the upper section of the mountain.

 

12. At times there may be dangerous wildlife near the summit.  On 28 June 2004 Christoph Weber of VEI reported seeing a deadly Egyptian cobra on the track between the north and south crater.  From 27- 28 July 2004 there was a male leopard roaming around the craters.  It came very close to the tents at night and seemed to be following us when we were walking after dark.  Baboons are common during the day and are potentially dangerous.

 

13. From 1998-2000 some travelers on the route to Lake Natron and Lengai were attacked by armed bandits, rumored to be Somalis.  Security has now improved, and as of July 2001 the route was considered safe again.  However, in August 2004 a Lengai climber, Thomas Gesthuizen,  reported that his group almost drove into a trap about a half hour out of Engare Sero en-route to Mto Wa Mbu.  The trap consisted of a piece of wood with large spikes that had been placed in the road, which would have destroyed their tires if not seen in time and would be very difficult to see at night.  Tanzanians said this was a typical way that bandits disable vehicles before robbing them.

14. In July 2004 a number of young children climbed to the crater.  Lengai is really not a suitable place for children to visit, simply because of the many dangers.  The risk is increased if their parents are also inexperienced with Lengai.


 

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