Ol Doinyo Lengai

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  • Primary Volcano Type
  • Last Known Eruption
  • 2.764°S
  • 35.914°E

  • 2962 m
    9715 ft

  • 222120
  • Latitude
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  • Summit
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    Number

17 February-23 February 2010

According to Frederick Belton's website, geologists that had climbed Ol Doinyo Lengai on 11 February saw periodic eruptions from a small fissure, and steam emissions from an area of the crater rim next to a part that had collapsed. Another group of geologists that visited during 14-15 February noted three new hornitos on the W part of the crater floor that were black and very fresh. They also noted a cone-shaped gray hornito on the middle of the floor and a new black lava flow to the S.

Source: Ol Doinyo Lengai (Fred Belton)



 Available Weekly Reports


2010: February
2008: January | February | March | April | June | October
2007: July | September | October | November | December
2006: March | April
2005: August
2002: August


17 February-23 February 2010

According to Frederick Belton's website, geologists that had climbed Ol Doinyo Lengai on 11 February saw periodic eruptions from a small fissure, and steam emissions from an area of the crater rim next to a part that had collapsed. Another group of geologists that visited during 14-15 February noted three new hornitos on the W part of the crater floor that were black and very fresh. They also noted a cone-shaped gray hornito on the middle of the floor and a new black lava flow to the S.

Source: Ol Doinyo Lengai (Fred Belton)


1 October-7 October 2008

According to Frederick Belton's website, a local camper reported a small eruption from Ol Doinyo Lengai on 1 October. Details of the eruption were not provided.

Source: Ol Doinyo Lengai (Fred Belton)


25 June-1 July 2008

According to Frederick Belton's website, visitors whom climbed Ol Doinyo Lengai on 18 June reported that the new active cone covered the former crater floor entirely except for an area N of the summit. The new cone's W, N, and E sides stood about 30 m above the rim of the former crater and enclosed a deep crater. The visitors saw a few small vents on the crater's floor. Frequent emissions of ash-poor plumes originated from the SW part of the crater's floor, producing light ashfall. They heard continuous loud rumbling noises, occasional gas-jetting sounds, and rockfalls.

Source: Ol Doinyo Lengai (Fred Belton)


9 April-15 April 2008

According to Frederick Belton's Ol Doinyo Lengai website, a visitor observed an ash plume during an overflight on 8 April.

Source: Ol Doinyo Lengai (Fred Belton)


12 March-18 March 2008

Based on a pilot observation, the Toulouse VAAC reported that an ash plume rose to an altitude of 12.2 km (40,000 ft) a.s.l. on 13 March. The plume was not confirmed using satellite imagery. A plume at an altitude of 13.7 km (45,000 ft) a.s.l. was observed on satellite imagery on 16 March.

Source: Toulouse Volcanic Ash Advisory Centre (VAAC)


5 March-11 March 2008

Based on pilot reports, MWO reports, and observations of satellite imagery, the Toulouse VAAC reported that ash plumes rose to altitudes of 8.8-10.7 km (29,000-35,000 ft) a.s.l. during 5-6 and 9 March. A cloud at an altitude of 12.2 km (40,000 ft) a.s.l. that possibly contained ash was detected in satellite imagery on 11 March. The cloud drifted S.

Source: Toulouse Volcanic Ash Advisory Centre (VAAC)


27 February-4 March 2008

According to Frederick Belton's Ol Doinyo Lengai website, a visitor reported a large plume accompanied by a "bang" during 26-27 February. The Toulouse VAAC reported that a pilot observed an ash plume that rose to an altitude of 10.7 km (35,000 ft) a.s.l. on 27 February. Another possible ash plume rose to the same altitude on 28 February and drifted SW. Based on a SIGMET, pilot reports, and observations of satellite imagery, the VAAC reported that eruption plumes possibly containing ash rose to altitudes of 10.7-13.7 km (35,000-45,000 ft) a.s.l. during 29 February and 3-4 March.

Sources: Ol Doinyo Lengai (Fred Belton), Toulouse Volcanic Ash Advisory Centre (VAAC)


20 February-26 February 2008

The Toulouse VAAC reported that a plume from Ol Doinyo Lengai was observed by pilots on 21 February and rose to an altitude of 18.3 km (60,000 ft) a.s.l. Based on a Significant Meteorological Information (SIGMET) report, an ash plume rose to an altitude of 14 km (46,000 ft) a.s.l. on 24 February.

Source: Toulouse Volcanic Ash Advisory Centre (VAAC)


13 February-19 February 2008

The Toulouse VAAC reported that an ash plume from Ol Doinyo Lengai was observed by pilots on 15 February and rose to an altitude of 11.6 km (38,000 ft) a.s.l.

Source: Toulouse Volcanic Ash Advisory Centre (VAAC)


6 February-12 February 2008

According to Frederick Belton's Ol Doinyo Lengai website, a local camp manager reported to a visitor, that several large explosive eruptions accompanied by "bangs" on 1 February. The manager noted that ash plumes were originating from a location in the crater that was further N than previous locations. The visitor saw ash plumes on 3 February that rose to altitudes of 3.2-3.3 km (10,500-10,800 ft) a.s.l. The next day, an ash plume rose to an altitude of 4.3 km (14,100 ft) a.s.l. Eruptions also occurred on 6 February.

Source: Ol Doinyo Lengai (Fred Belton)


16 January-22 January 2008

A visitor to Ol Doinyo Lengai reported that it erupted on 14 January. A "shower of stones" fell at their location about 50 m from the summit and a lava flow went another direction.

Source: Ol Doinyo Lengai (Fred Belton)


26 December-1 January 2008

The Toulouse VAAC reported that an ash plume from Ol Doinyo Lengai was observed by visiting scientists on 29 December and rose to an unreported altitude.

Source: Toulouse Volcanic Ash Advisory Centre (VAAC)


19 December-25 December 2007

The Toulouse VAAC reported that an ash plume from Ol Doinyo Lengai was observed by visiting scientists on 20 December and rose to an unreported altitude.

Source: Toulouse Volcanic Ash Advisory Centre (VAAC)


12 December-18 December 2007

Based on information from the Tanzania MVO and pilot reports, the Toulouse VAAC reported that an ash plume from Ol Doinyo Lengai rose to an altitude of 6.1 km (20,000 ft) a.s.l. on 13 December.

Source: Toulouse Volcanic Ash Advisory Centre (VAAC)


7 November-13 November 2007

Based on information from the Tanzania MVO, the Toulouse VAAC reported that Ol Doinyo Lengai erupted on 7 November and remained active. According to Frederick Belton's website, an observer saw a "smoke" plume rise to an altitude of 3.2-3.5 km (10,500-11,500 ft) a.s.l. and drift WSW towards the Gol Mountains on 10 November.

Sources: Toulouse Volcanic Ash Advisory Centre (VAAC), Ol Doinyo Lengai (Fred Belton)


31 October-6 November 2007

According to Frederick Belton's Ol Doinyo Lengai website, the owner of a camp on the S shore of Lake Natron reported that ash eruptions continued "daily" and some "lava eruptions" were observed at night. Based on pilot observations, the Toulouse VAAC reported an eruption on 6 November.

Sources: Toulouse Volcanic Ash Advisory Centre (VAAC), Ol Doinyo Lengai (Fred Belton)


24 October-30 October 2007

Based on pilot observations, the Toulouse VAAC reported that ash plumes from Ol Doinyo Lengai rose to altitudes of 3.2-4.6 km (10,500-15,000 ft) a.s.l. on 23 October. According to Frederick Belton's Ol Doinyo Lengai website, a pilot photographed an ash column rising vertically from the summit on approximately 25 October.

Sources: Toulouse Volcanic Ash Advisory Centre (VAAC), Ol Doinyo Lengai (Fred Belton)


5 September-11 September 2007

An eruption of Ol Doinyo Lengai on 4 September produced an ash plume that was reported by a pilot and visible on satellite imagery. Ashfall lasted about 12 hours in the village of Engare Sero, about 18 km N. Dark areas on the NW, W, and E flanks that were noticeable on satellite imagery from 4 September were possibly due to recent lava flows and burned vegetation or both. An ash plume was also visible, drifting SSW.

Multiple thermal anomalies at and around the summit were present on satellite imagery since 21 August 2007, and on the flanks on 31 August and 1 September.

Sources: Frank Moeckel, Matthieu Kervyn, Mercator and Ortelius Research Center for Eruption Dynamics, Ghent University, Greg Vaughan, Jet Propulsion Laboratory, Thomas M. Holden, Nature Discovery, Ol Doinyo Lengai (Fred Belton), The Guardian News


25 July-31 July 2007

Ol Doinyo Lengai is frequently the scene of fluid but very small volume lava flows in its summit crater, including a few that passed over the crater rim and begun the long descent down the mountain. As noted here last week, news reports had indicated that products of the volcano's 19-July eruption had entered inhabited areas. Subsequent investigations have cast doubt on those earlier claims.

Discussions this week by volcanologist Gerald Ernst with contacts in the region revealed that neither aviators, guides, scientists, nor locals had seen dramatic eruptive events at the mountain. The summit crater was intact, but eruptions were confined to the summit area. What was interpreted from a distance as a modest landslide in the crater may have sent out a dust cloud. That cloud could have been confused with ash from a large flank eruption.

To help shed light on the situation, Greg Vaughan of the Jet Propulsion Labs had a preliminary look at some ASTER satellite data of the volcano and concluded that in mid-June through late July the summit crater was likely to have continued to emit lava. The 20 July thermal emissions appeared no larger than those on 18 June. Those from 15 April appeared weaker. The images supported summit lava eruptions but failed to document any lava that had spilled over the crater rim.

Sources: Gerald Ernst, Centre for Environmental & Geophysical Flows, Department of Earth Sciences, University of Bristol, Greg Vaughan, Jet Propulsion Laboratory


18 July-24 July 2007

According to news reports, an eruption began at Ol Doinyo Lengai around 19 July, forcing villagers living near the volcano to evacuate. An article stated that, "...more than 1,500 people, most of them Maasai families, vacated their homes in Ngaresero, Orbalal and Nayobi villages following the tremors that triggered the volcanic eruption." "Villagers are reported to have heard roaring...before the volcano started discharging ash and lava." There were reports of a damaged school and two injuries, but no reports of deaths.

Sources: East African Standard, Associated Press


5 April-11 April 2006

On Frederick Belton's Ol Doinyo Lengai website, information was compiled about the activity that began around 30 March. According to the site, a bush pilot reported that a lava flow and lava fountains were emitted on the 30th, but there were no ash emissions. A steam plume was visible that may have been mistakenly described as ash in news reports. According to an observer in Tanzania, on 4 April a very large lava flow was visible on the volcano's W flank. The lava flow was over 1 km long and had traveled down the flank of the volcano and into a gorge. There were no signs that the flow was still hot. Photographs revealed that another lava flow may have traveled W of the volcano on 3 or 4 April. On 7 or 8 April, active lava was contained within a new lava lake. Contrary to news reports, a local tour operator stated that there were no evacuations from villages near the volcano.

Source: Ol Doinyo Lengai (Fred Belton)


29 March-4 April 2006

According to news reports, an eruption began at Ol Doinyo Lengai around 30 March, forcing villagers living near the volcano to evacuate. An article stated that, "Eyewitnesses said they heard a rumbling noise before the volcano began discharging ash and lava, prompting local residents to flee the area in their hundreds. District officials estimated that about 3,000 people from Nayobi, Magadini, Engaruka, Malambo, Ngaresero, Gelai Bomba, and Kitumbeine villages left their homes within a few hours of the eruption..." There were reports of polluted water sources and destroyed vegetation, but no reports of deaths or injuries.

Sources: The Guardian News, Associated Press


17 August-23 August 2005

During a trip to Ol Doinyo Lengai by Fred Belton during 19 July to 9 August, three eruptions occurred at cone T58C on 20 and 21 July, one of which lasted 20 hours. No further eruptions were observed through 9 August. The most recent eruption prior to 20 July occurred on 9 July when large lava flows completely covered the campsite in the E part of the crater. Photos indicated that there may have been infrequent activity at the volcano at least as long ago as 15 May. No new cones had formed at the volcano since 15 July 2004 when T58C was created.

Source: Ol Doinyo Lengai (Fred Belton)


7 August-13 August 2002

During 4-9 August, Ol Doinyo Lengai was in a heightened state of volcanic activity. A group visiting the volcano for 5 days saw episodes of sudden explosive lava fountaining from cracks and fissures in the crater floor. Sulfurous gases were also unusually strong in the central crater. Around 0210, part of an expedition camp in the crater of Ol Doinyo Lengai was destroyed by extremely fluid pahoehoe lava flows. A local guide received several second-degree burns on one foot when material in his tent was ignited by the lava.

Source: Ol Doinyo Lengai (Fred Belton)


Summary of eruption dates and Volcanic Explosivity Indices (VEI).

Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
2011 Jun 22 (in or before) 2013 Jul (continuing) Confirmed   Historical Observations
2007 Jun 2010 Oct 9 (?) ± 1 days Confirmed 3 Historical Observations
1994 Sep 18 2006 Jul (?) Confirmed 1 Historical Observations North Crater
1983 Jan 1 1993 Sep 24 Confirmed 2 Historical Observations North Crater
[ 1974 Aug ] [ 1974 Sep ] Discredited    
[ 1969 Jul (?) ] [ Unknown ] Uncertain    
1967 Jul 8 1967 Sep 4 Confirmed 3 Historical Observations North Crater
1960 Mar (in or before) 1966 Nov 28 ± 30 days Confirmed 3 Historical Observations North Crater
1958 Feb 6 (in or before) Unknown Confirmed 1 Historical Observations North Crater
1955 Jan 19 1955 Jan 20 Confirmed 2 Historical Observations North Crater
1954 Jul 26 ± 5 days 1954 Sep Confirmed 2 Historical Observations North Crater
1940 Jul 24 1941 Feb Confirmed 3 Historical Observations North Crater
1926 Unknown Confirmed 2 Historical Observations North Crater
1921 Feb Unknown Confirmed 2 Historical Observations North Crater
1916 Dec 1 ± 30 days 1917 Jun Confirmed 3 Historical Observations North Crater
1914 Aug 15 ± 270 days 1915 Confirmed 0 Historical Observations North Crater
1913 Unknown Confirmed 0 Historical Observations
1907 ± 3 years 1910 Aug 4 (in or after) Confirmed 0 Historical Observations North Crater
1904 Unknown Confirmed 0 Historical Observations North Crater
[ 1894 ] [ Unknown ] Discredited    
1882 1883 Confirmed 2 Historical Observations North Crater
1880 Dec Unknown Confirmed 2 Historical Observations North Crater
1350 (?) Unknown Confirmed   Tephrochronology Footprint Tuff
0700 (?) Unknown Confirmed   Tephrochronology Namrod Ash
0050 BCE (?) Unknown Confirmed   Tephrochronology BTA Tuffs
1550 BCE ± 1000 years Unknown Confirmed   Tephrochronology

The following references are the sources used for data regarding this volcano. References are linked directly to our volcano data file. Discussion of another volcano or eruption (sometimes far from the one that is the subject of the manuscript) may produce a citation that is not at all apparent from the title. Additional discussion of data sources can be found under Volcano Data Criteria.

Bell K, Dawson J B, 1995. Nd and Sr isotope systematics of the active carbonatite volcano, Ol Doinyo Lengai. In: Bell K, Keller J (eds), {Carbonatite Volcanism, Oldoinyo Lengai and the Petrogenesis of Natrocarbonatites}, Berlin: Springer-Verlag, p. 100-112.

Dawson J B, 1962. The geology of Oldoinyo Lengai. Bull Volc, 24: 349-387.

Dawson J B, Keller J, Nyamweru C, 1995. Historic and recent eruptive activity of Oldoinyo Lengai. In: Bell K, Keller J (eds), {Carbonatite Volcanism, Oldoinyo Lengai and the Petrogenesis of Natrocarbonatites}, Berlin: Springer-Verlag, p. 4-22.

Green J, Short N M, 1971. Volcanic Landforms and Surface Features: a Photographic Atlas and Glossary. New York: Springer-Verlag, 519 p.

Hay R L, 1989. Holocene carbonatite nephelinite tephra deposits of Oldoinyo Lengai, Tanzania. J Volc Geotherm Res, 37: 77-91.

Katsui Y (ed), 1971. List of the World Active Volcanoes. Volc Soc Japan draft ms, (limited circulation), 160 p.

Keller J, 1989. . (pers. comm.).

Keller J, Klaudius J, Kervyn M, Ernst G G J, Mattsson H B, 2010. Fundamental changes in the activity of the natrocarbonatite volcano Oldoinyo Lengai, Tanzania I. New magma composition during the 2007-2008 explosive eruptions . Bull Volc, 72: 893-912.

Kervyn M, Ernst G G J, Keller J, Vaughan R G, Klaudius J, Pradal E, Belton F, Mattsson H B, Mbede E, Jacobs P, 2010. Fundamental changes in the activity of the natrocarbonatite volcano Oldoinyo Lengai, Tanzania II. Eruptive behaviour during the 2007-2008 explosive eruptions . Bull Volc, 72: 913-931.

Kervyn M, Ernst G G J, Klaudius J, Keller J, Kervyn F, Mattsson H B, Belton F, Mbede E, Jacobs P, 2008. Voluminous lava flows at Oldoinyo Lengai in 2006: chronology of events and insights into the shallow magmatic system. Bull Volc, 70: 1069-1086.

Mattsson H B, Vuorinen J, 2009. Emplacement and inflation of natrocarbonatitic lava flows during the March-April 2006 eruption of Oldoinyo Lengai, Tanzania. Bull Volc, 71: 301-311.

Nyamweru C, 1997. Changes in the crater of Oldoinyo Lengai: June 1993 - February 1997. J African Earth Sci, 25: 43-53.

Nyamweru C, 1990. Observations on changes in the active crater of Ol Doinyo Lengai from 1960 to 1988. J African Earth Sci, 11: 385-390.

Richard J J, Neumann van Padang M, 1957. Africa and the Red Sea. Catalog of Active Volcanoes of the World and Solfatara Fields, Rome: IAVCEI 4: 1-118.

Vaughan R G, Kervyn M, Realmuto V, Abrams M, Hook S J, 2008. Satellite measurements of recent volcanic activity at Oldoinyo Lengai, Tanzania. J Volc Geotherm Res, 173: 196-206.

The symmetrical Ol Doinyo Lengai stratovolcano is the only volcano known to have erupted carbonatite tephras and lavas in historical time. The prominent volcano, known to the Maasai as "The Mountain of God," rises abruptly above the broad plain south of Lake Natron in the Gregory Rift Valley. The cone-building stage of the volcano ended about 15,000 years ago and was followed by periodic ejection of natrocarbonatitic and nephelinite tephra during the Holocene. Historical eruptions have consisted of smaller tephra eruptions and emission of numerous natrocarbonatitic lava flows on the floor of the summit crater and occasionally down the upper flanks. The depth and morphology of the northern crater have changed dramatically during the course of historical eruptions, ranging from steep crater walls about 200 m deep in the mid-20th century to shallow platforms mostly filling the crater. Long-term lava effusion in the summit crater beginning in 1983 had by the turn of the century mostly filled the northern crater; by late 1998 lava had begun overflowing the crater rim.