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Ol Doinyo Lengai
Image of 1966 eruption
Elevation	2,960 m (9,711 ft)
Location	Tanzania
Range	Great Rift Valley
Coordinates	2°45′5″S 35°54′8″E / 2.75139°S 35.90222°E / -2.75139; 35.90222
Type	Stratovolcano
Last eruption	2009 (ongoing)[1][2]
Easiest route	Scramble

Ol Doinyo Lengai is a volcano located in the north of Tanzania and is part of the volcanic system of the Great Rift Valley in Eastern Africa. It is located in the eastern Rift Valley, south of both Lake Natron and Kenya. It is unique among active volcanoes in that it produces natrocarbonatite lava, a unique occurrence of volcanic carbonatite. Further, the temperature of its lava as it emerges is only around 510 °C (950 °F). A few older extinct carbonatite volcanoes are located nearby, including Homa Mountain.

Geology

"Ol Doinyo Lengai" means "Mountain of God" in the language of the native Maasai people.^[3] The record of eruptions on the mountain dates to 1883, and flows were also recorded between 1904 and 1910 and again between 1913 and 1915. A major eruption took place in June 1917, which resulted in volcanic ash being deposited about 48 kilometres away.

A similar eruption took place for several months in 1926 and between July and December 1940, resulting in the ash being deposited as far as Loliondo, which is 100 kilometres away. Several minor eruptions of lava were observed in 1954, 1955, 1958 the early 1960s.

In modern times, Ol Doinyo Lengai erupted on August 14, 1966. Two geologists — J. B. Dawson and G. C. Clark — who visited the crater a week later, reported seeing “a thick column of black ash” that rose for approximately three thousand feet above the volcano and drifted away northwards towards Lake Natron. When the two climbed the cone-shaped vent, they reported seeing a continuous discharge of gas and whitish-grey ash and dust from the centre of the pit.

Volcanic activity in the mountain caused daily earth tremors in Kenya and Tanzania beginning on July 12, 2007. The latest to hit parts of Nairobi city was recorded on July 18, 2007 at 8.30pm (Kenyan Time). The strongest tremor measured 6.0 on the Richter scale. Geologists suspected that the sudden increase of tremors was indicative of the movement of magma through the Ol Doinyo Lengai. The volcano finally erupted on September 4, 2007, sending a plume of ash and steam at least 18 kilometers downwind and covering the north and west flanks in fresh lava flows. The eruption has continued intermittently into 2008, as of the end of February it was reported that the eruption appeared to be gathering strength, with a major outburst taking place on March 5. During April periods of inactivity have been followed by eruptions on April 8 and 17. Eruptive activity continued until late August 2008. A visit to the summit in September 2008 discovered that lava emission had resumed from two vents in the floor of the new crater. Visits to the crater in March/April 2009 showed that even this activity appears to have ceased.^[4].

Lava

Whereas most lavas are rich in silicate minerals, the lava of Ol Doinyo Lengai is rich in the rare sodium and potassium carbonates, nyerereite and gregoryite. Due to this unusual composition, the lava is erupted at relatively low temperatures (approximately 500-600 degrees Celsius). This temperature is so low that the molten lava appears black in sunlight, rather than having the red glow common to most lavas. It is also much more fluid than silicate lavas. The sodium and potassium carbonate minerals of the lavas formed by Ol Doinyo Lengai are unstable at the Earth's surface and susceptible to rapid weathering, quickly turning from black to grey in color. The resulting volcanic landscape is different from any other in the world.

Gallery

Crater of the Ol Doinyo Lengai with recent lava flow, 15th. August 2007.

Ol Doinyo Lengai erupting in March 2008.

Ol Doinyo Lengai after an explosive eruption.

Image of the volcano sending a plume of ash and steam southward.

See also

• List of volcanoes in Tanzania

References

External links

• Ol Doinyo Lengai at nationalgeographic.com
• Ol Doinyo Lengai at Stromboli Online
• Ol Doinyo Lengai at Volcano World
• St Lawrence University Oldoinyo Lengai
• Middle Tennessee State Univ. Mountain of God
• Volcano Discovery Ol Doinyo Lengai volcano, Tanzania
• Ol Doinyo Lengai videos, Tanzania

From Wikitravel

Location
Flag
Quick Facts
Capital	Dodoma (moved from Dar es Salaam in 1973)
Government	Republic
Currency	Tanzanian shilling (TZS)
Area	945,087 km2
Population	37,187,939 (July 2002 est.)
Language	Kiswahili or Swahili (official); English (official, commerce); Arabic (in Zanzibar), and many local languages.
Religion	Mainland - Christian 30%, Muslim 35%, indigenous beliefs 35%; Zanzibar - 99% Muslim
Electricity	230V/50Hz (Indian or UK plug)
Calling Code	+255 (007 from Kenya and Uganda)
Internet TLD	.tz
Time Zone	UTC +3

Tanzania [1] is the largest country in East Africa, bordered by Kenya and Uganda to the north; Rwanda, Burundi, and the Democratic Republic of the Congo to the west, and Zambia, Malawi, and Mozambique to the south.

Understand

Geography

A large central plateau makes up most of the mainland, at between 900 m and 1800 m. The mountain ranges of the Eastern Arc and the Southern and Northern Highlands cut across the country to form part of the Great Rift Valley.

A land of geographical extremes, Tanzania houses the highest peak (Mount Kilimanjaro), the lowest point (the lake bed of Lake Tanganyika), and a portion of the largest lake (Lake Victoria, shared with Uganda and Kenya) on the African continent.

Climate

Tanzania's weather varies from humid and hot in low lying areas, such as Dar es Salaam, to hot during the day and cool at night in Arusha. There are no discernible seasons, such as winter and summer -- only the dry and wet seasons. Tanzania has two rainy seasons: The short rains from late-October to late-December, a.k.a. the Mango Rains, and the long rains from March to May.