The Vulcanology of Kilimanjaro

Volcano type - Stratovolcano
Location - Tanzania, 3.07°S / 37.35°E
Summit elevation 5895 m
Last eruptions - None in historic time (but probably active during the past 10,000 years)
Typical eruption style - Explosive.

Kilimanjaro is a giant stratovolcano reaching an elevation of 5,895m.This volcano's highest and youngest cone is named Kibo. Shira to the west and Mawenzi in the east are older cones that make up Kilimanjaro. Kibo has not been active in modern times, but steam and sulfur are still emitted. At the top of Kibo's summit is a 2.25 km diameter crater.

Kilimanjaro is part of an E-W belt of about 20 volcanoes near the southern end of the East African Rift Valley. Also in this belt are Ngorongoro caldera - a superb wildlife refuge, Ol Donyo Lengi - a carbonitite volcano, and Meru.

Kilimanjaro is a triple volcano with the youngest and central peak of Kibo being 7.5-8.7 miles (12-14 km) from Shira to the west and Mawenza to the east.

Shira is topped by a broad plateau, perhaps a filled caldera, and erosion has cut the rim a lot. In contrast, Mawenzi's summit is a rocky peak surrounded by cliffs .0.5 km) to 1.5 km high. Erosion has removed the original crater, and a great horseshoe shaped ridge opens to the northeast.

Mile-deep gullies with 30-45 degree gradients make many places practically inaccessible. Massive series of radial and concentric dyke swarm make up more than 30-40 percent of the summit area of Mawenzi.

Kibo's glacier-clad summit, the highest spot in Africa, is a 1.2 x 1.7 mile (1.9 x 2.7 km) caldera, with an inner crater nearly a mile (1.3 km) wide, and inside that a deep, 1,148 ft. (350 m) wide central pit.

Original volcanic forms are preserved at the summit and on many of the flanks, except on the south side where glaciers have cut deeply into the cone. Nearly 250 satellite cones occur on Kilimanjaro, most following SE and NW trends.

Estimates tell us that of a total volume of about 1,150 cu. miles, Mawenzi and Shira each contribute roughly 120 cu. mi. of andesites and basalts, Kibo has the same volume of similar but unexposed rocks, plus an additional 107 cu. miles.

Interestingly, more than half of Kilimanjaro's volume is represented by older, basal basalts (672 cu. mi.). This basaltic shield is the most important, but least obvious element of a complex volcano..

The older cone of Shira forms the broad WNW shoulder of Kilimanjaro, and Mawenzi forms a prominent, sharp-topped peak on the ESE flank. Numerous satellite cones occupy a rift zone to the NW and SE of Kibo, the central stratovolcano. A 2.4 x 3.6 km caldera gives the summit of Kibo an elongated, broad profile. Most of Kilimanjaro was made during the Pleistocene, but a group of summit craters are from the Holocene.

For more information on climbing Kilimanjaro or visiting Tanzania's mountains click Climb Kilimanjaro with Mountain Kingdom Safaris


article source: ArticleStreet.com
article by: Roy J Hinde
about the author:

• Roy J Hinde M.Sc. is a former research scientist who now is a director of Wild Things Safaris Ltd and runs the marketing for MK safaris Climb Kilimanjaro.

* * *