MOUNT OLDONYO LENGAI OVERVIEW
Ol Doinyo Lengai volcano, altitude 2960 meters (9711 feet), is a unique and extremely fascinating volcano that towers above the East African Rift Valley in Northern Tanzania, just south of Lake Natron. It is the only volcano in the world that sometimes erupts natrocarbonatite lava, a highly fluid lava that contains almost no silicon.
Natrocarbonatite lava is also much cooler than other lavas, being only about 950 degrees F (510 degrees C) compared to temperatures over 2000 degrees F (~1100 degrees C) for basaltic lavas. Natrocarbonatite is the most fluid lava in the world. Lava with a low gas content can flow like a whitewater stream, and actually has a viscosity near that of water.
Natrocarbonatite lava glows orange at night, but is not nearly as bright as silicon-based lavas since it is not as hot. During the day it is not incandescent; most flows look like very fluid black oil, or brown foam, depending on the gas content. In the past, some visitors to the crater believed they were seeing mud flows. Most newly solidified lava is black and contains crystals that sparkle brightly in the sun.
There are also sometimes small flows known as “squeeze-ups” that are light gray when they flow and harden. Contact with moisture rapidly turns natrocarbonatite lava white because of chemical reactions that occur when the lava absorbs water.
Eventually the water absorption process turns lava flows into soft brown powder. During dry weather the whitening of flows happens over a period of a few days to a couple of weeks, depending on the thickness of the flow. In rainy weather the lava surface turns white immediately.
In parts of the crater that have been inactive for several months, the ground is light brown/white and so soft that one sinks into it when walking.
Ol Doinyo Lengai also has phases of explosive activity during which the composition of the lava may contain much more silicate material, reducing its viscosity. In this type of eruption there is no fluid lava and activity takes the form of ash eruptions accompanied by ejection of blocks and bombs.
However, initial phases of an explosive eruption may include strong lava fountains. The two most recent explosive eruptions occurred during 1966-1967 and 2007-2008.
Since the mid 1980’s, lava flows, and to a much lesser extent, explosive eruptions, have been witnessed by many observers of Ol Doinyo Lengai. Natrocarbonatite lava eruptions are usually centered in one or more small cones that have been formed on the crater floor by previous eruptions of lava.
These eruptions have typically taken the form of open lava pools or lakes that may or may not be overflowing, lava flows issuing from holes or cracks inside or near the base of the cones, or lava splashes or fountains from the summit vents of the cones.
The activity is not well understood but is thought to be a function of the plumbing of the crater, the level of the lava within the plumbing, and the gas content of the lava. No one knows what causes the lava to flow out at any particular time or how the various vents in the crater are interconnected.
Mineralogists would like to understand how the lava evolves under the surface and why it has its unusual chemical composition, but that also is unknown, although there are several theories. Finally, no one has any idea why the pattern of frequent small lava flows gave way to explosive activity at the end of August 2007 and how that may have related to earthquakes in the region during the previous two months.
Eruption of T58C on July 15, 2004
3 Days Mount Ol Donyo Lengai and lake Natron
Climbing to the summit [2890 mt / 9481 ft] of the active volcano, which is locally regarded as the sacred Mountain of God in the Maa Language, is possible without specific equipment but the ascent is challenging because the mountain is very steep. The best time to climb the mountain is early in the morning before the sun is getting to hot. The upper part of the volcano is the hardest to climb. The slope is about 45 to 55 degrees. The surface is covered by a thin slippery layer of lava under which the ash is still loose. You will proceed almost crawling, going up and sliding down continuously. The summit tent to be hazy and cloudy except for a few hours early in the morning when you should be able to see the sun rising over Mount Kilimanjaro. There is a cold wind and temperature is about 10 degrees. To descent it will take you approximately 5 hours.
Until 2007 eruption there were two craters, the active northern one about 200 meters deep and the sleeping southern one. After the eruption they melted together.
Mt. Ol Doinyo Lengai is the only known volcano in the world that sometimes erupts natrocarbonatite lava, a highly fluid lava that contains almost no silicon. Natrocarbonatite lava (most fluid lava) is also much cooler than other lavas. During the day most of this lava flows look like fluid black oil. Some feel the lava flows resemble mud like?flows. Natrocarbonatite lava turns white when in contact with moisture. During rainy periods, the lava turns white almost immediately whilst this whitening takes longer during the dry periods.
Herds of zebra and wildebeest can sometimes be seen on the trip. A trip to the mountain can also cover other nearby areas of interest like Lake Natron, which is a breeding ground for all East African flamingos and other birds. There are several Maasai bomas (villages) which can be visited on additional cost, just talk to your driver guide. If you are interested, you can visit the nearby Mount Gelai with geysers and a brilliant waterfall.
- Day 1: Moshi/Arusha – Lake Natron
Departure from Moshi or Arusha at 7.00 am and drive to Ngaresero village (Lake Natron) with packed lunch. After lunch you will travel north along the Great Rift Valley wall to Lake Natron and the village of Ngare Sero near the holy Maasai mountain “Ol ‘Doinyo Lengai”. This is about 8 hours driving. Optional: In the late afternoon, together with a local Maasai guide, you hike through a shady gorge to the Engero Sero waterfalls. There you’ll have the opportunity to swim in a beautiful natural swimming pool surrounded by steep cliffs.Meal plan: lunch, dinner
Possible Accommodation: Maasai Giraffe Eco Lodge or Campsite
- Day 1: Moshi/Arusha – Lake Natron
- Day 2: Climb Ol Doinyo Lengai
At very early morning 1:00 a.m. drive to the base of the Ol’ Doinyo Lengai mountain to start the climb. You will reach the summit during sunrise and spend some time there before coming down to the base of the mountain. From there clients will be transferred by Jeep to Giraffe Eco Lodge or Campsite for shower and rest.Optional:
In the afternoon you drive to the edge of Lake Natron, one of the most alkaline lakes in the world. With millions of small crustaceans, the lake is a refuge for thousands of flamingos and one of the most important flamingo breeding grounds on earth.Meal plan: breakfast, lunch, dinner
Possible Accommodation: Maasai Giraffe Eco Lodge or Campsite
- Day 2: Climb Ol Doinyo Lengai
- Day 3: Lake Natron – Arusha/Moshi
After breakfast relaxation and then drive back to Arusha or Moshi with lunch box or additional program (see our options).Optional:
Before leaving for Arusha or Moshi a visit to a Maasai village (Boma) can be arranged to interact with Maasai people and learn their culture and everyday activities.Meal plan: breakfast, lunch
- Day 3: Lake Natron – Arusha/Moshi
INCLUDE
- Transport from and to your hotel/residence or airport/seaport
- English-speaking professional driver/mountain guides
- 4×4 vehicle
- Guides, Porters, cook salaries
- All Park fees
- Accommodation and meals as mentioned in the itinerary or as agreed. N. B. accommodation mentioned in the itinerary is dependent on availability at the time of booking; alternatives of a similar class may be booked instead
- All camping gear (if applicable)
- Drinking water during the game drives/walking safaris/mountain hikes
- Driver’s salary and allowances and park fees for vehicle and driver
EXCLUDE
- International/national flights and visa fees
- Extras, personal expenses i.e. soft and alcoholic drinks, telephone, souvenirs, laundry etc.
- Travel, medical, injury and luggage insurance
- Flying doctor rescue services
- Government-imposed increases in taxes and/or park entrance fees
- Tips to the driver & guides
- Anything else not mentioned in the inclusions
- Optional activities not outlined in the itinerary