Mount Oldoinyo Lengai
Northern Tanzania Region
Mount Oldoinyo Lengai, located in northern Tanzania's Arusha region, is a unique and active volcano renowned for erupting natrocarbonatite lava, a rare type of low-temperature, highly fluid magma found nowhere else on Earth. The volcano features a symmetric cone rising over 1,800 meters above the surrounding rift valley, with two craters at its summit. The northern crater remains active with lava flows resembling pahoehoe, while the southern crater is inactive and sometimes holds water. The volcano is culturally significant to the Maasai and Sonjo peoples, who call it 'The Mountain of God' and associate it with the god Engai. Geologically, Mount Oldoinyo Lengai is part of the Gregory Rift within the East African Rift system, with volcanic activity shifting northeastward over time to this site. Its volcanic cone is primarily composed of melilite, nephelinite, and phonolite, with carbonatitic lavas appearing only recently in the northern crater. These carbonatite lavas chemically alter rapidly upon exposure, forming unique secondary minerals. The surrounding landscape includes parasitic vents and evidence of past debris avalanches. The region around the volcano supports livestock farming and growing tourism, offering visitors a compelling blend of natural wonder and cultural heritage.
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Tip: Visitors are advised to plan their visit during dry seasons for safer and clearer trekking conditions. Due to the volcano's activity, checking current volcanic status and local guidance before visiting is essential. Booking guided tours in advance is recommended to explore safely and gain cultural insights. Visitors should prepare for high-altitude trekking and variable weather conditions. Discounts may be available for group bookings or through tour operators.
Interesting facts
- •Mount Oldoinyo Lengai is the only volcano on Earth known to have erupted natrocarbonatite lava during historical times.
- •Its name means 'The Mountain of God' in the Maasai language, reflecting its cultural significance.
- •The volcano's natrocarbonatite lava is unusually low in temperature and highly fluid compared to typical volcanic lava.
- •Eruptions in 2007–2008 notably affected the surrounding region with ash deposits.
- •The volcano is part of the active East African Rift system, which is slowly spreading at about 3 millimeters per year.
History
Mount Oldoinyo Lengai was first explored between 1904 and 1915 and is part of the Ngorongoro volcanic highland system, active from the Miocene epoch to the present.
Volcanic activity in the region has shifted northeastward over time, culminating in the current activity at Oldoinyo Lengai.
The volcano's natrocarbonatite eruptions are unique in recorded history, with significant eruptions noted in 2007–2008.
The surrounding region has been inhabited by the Maasai and Sonjo peoples, who have long held the mountain sacred.
Place Guide
Northern Crater
The active northern crater features recent lava flows of natrocarbonatite magma, which are highly fluid and form distinctive pahoehoe-like surfaces. Small cones within the crater produce lava flows from their summits and flanks.
Southern Crater
An inactive crater occasionally filled with water, contrasting with the northern crater’s activity. It forms part of the mountain’s summit ridge and offers scenic views.
Parasitic Vents and Flanks
Various smaller vents such as Kirurum Crater and Nasira cones are located on the volcano’s flanks, contributing to its complex volcanic landscape.
