Geosphere Journal Entry

Geosphere Journal Entry

Tanzania Volcano Active Again (March 8, 2010)

Tanzania's Oldoinyo Lengai volcano or the "Mountain of God" is becoming active again after two years of calm. Eyewitnesses observed streams of black lava on the crater floor. Ash cones and hornitos, small mounds of volcanic material, were also visible at the volcano's summit. The strong smell of sulfur fumes rising from fumaroles filled the air.

Oldoinyo Lengai is a cone-shaped volcano found in the Great Rift Valley of eastern Africa. It's the only active volcano on the planet known to spew lava rich in sodium and potassium compounds but with almost none of the silicon-containing compounds usually found in lava. The volcano's unusual lava is more viscous, or flows more easily, and is darker than other lava. It's also much cooler, erupting at temperatures of 950°F (500°C) compared to over 2,000°F (1,100°C) for other lava. The lava turns white from reactions with moisture in the air, adding to Oldoinyo Lengai unique appearance.

The African continent is carried on the African tectonic plate. This plate is diverging, or spreading apart, along the Great Rift Valley running through East Africa as hot magma bubbles up from Earth's interior. East Africa may eventually split off from the African mainland as ocean water fills the valley floor of the growing rift.