Ol Doinyo Lengai: Mountain of god

Ol Doinyo Lengai is a 2960 m high volcano in the East African Rift Valley. It is located in northern Tanzania, about 120 km northwest of Arusha at Lake Natron.

The volcano is for the Masai the seat of their god Engai and the volcanic eruptions symbolize the wrath of the god. In the language of the Massai Ol Doinyo Lengai means as much as Gottesberg. In times of need the Massai make sacrifices. Often only milk and cattle blood is sacrificed, but occasionally a goat is also exposed in the crater.

For volcanologists Ol Doinyo Lengai is of special interest for another reason: it produces the coldest lava in the world. Its temperature varies between 490 and 590 degrees. This makes it only about half as hot as ordinary lava. It is extremely low viscosity and can flow as fast as water. The lava is natrocarbonatitic that was erupted in historical times only at this unique volcano. Of course, only a small part is made of natrocarbonatitic, the greater part is made up of foidite and phonolite.

The Ol Doinyo Lengai is located in the East African Rift Valley. It lies above the so-called Tanzania Craton.

The Crater of Ol Doinyo Lengai

The eruptive activity takes place mainly in the central crater area, which is filled with the eruption products. The level of the crater filling is subject to constant change. Sometimes its possible to walk in. A few meters below its surface, a large magma reservoir bubbles and large cavities are formed. Above ground, the lava erupts mainly effusive. Lavaspattering causes hornitos to grow, which tend to collapse suddenly. This makes the volcano very dangerous.
On our expeditions, injuries have been frequent. A Masai porter had both legs amputated. He collapsed through a thin crust of solidified lava into the lava flow below.

The level of crater filling is subject to constant change.
After a major eruption in 2007, the former crater was filled and a new cone with a deeper crater was formed.