Volcano of the Week!

10/03/2014-16/03/2014

This week’s volcano of the week is:

Kilimanjaro

Location: Tanzania

Type: Stratovolcano

Elevation: 5895 metres, 19,340 feet

Last Eruption: Unknown

Status: Dormant?

Details:

Kilimanjaro, Africa’s highest mountain is a massive 5895 metres (19,340 feet) stratovolcano, located in north Tanzania in the region of Kilimanjaro (latitude 3.07°S, longitude 37.35°E), north of the main town of Moshi. The mountain (well known for the presence of an ice capped summit on Kibo) consists of three stratovolcanoes, Kibo (being the highest peak and only potential active feature), Mwanzi situated east of Kibo and Shira situated west of Kibo and various other pyroclastic cones such as Chala and Kilema situated all around Kilimanjaro varying in size.

Shira is a 13,000 extinct volcano which was formed around the late Lower Pleistocene and has become deeply eroded now according to studies carried out by Downie et al (1972). In contrast, Mwanzi which became extinct before Shira sometime in the middle Pleistocene is 16,896 feet and contained two vents one and a half mile apart from each other and 40 miles in diameter.

Some lava flows have travelled 30 miles from the centre, had a volume of 220 cubic miles and varied greatly in nature. Lava flows up to 2000 feet in depth have also been witnessed on Mwanzi and evidence of lahars measuring 1.7 cubic miles in volume are also present in the Mwanzi region.

Compared to Mwanzi and Shira, Kibo is the only remaining potentially active volcanic feature on Kilimanjaro but has been in dormancy since 360,000 years. The slopes on the north and east of Kibo vary from 25° to 35° and the slopes in the west and south are much steeper. Kibo contains a summit two miles in diameter and a caldera measuring 2.5 by 3.6 kilometres within which an ash cone a result of Kibo’s last volcano activity exists. The well preserved ash cone contains the final active vent of Kilimanjaro and measures 370 yards in diameter, 425 feet in depth and 19,000 feet in height

Vast evidence of activity on Kibo is also present including lava flows and lahars along with pyroclastic rocks which travelled from the west to east. Lava flows and lahars have been witnessed not to far from the town of Moshi in the south and some lava flows from Kibo (at around 17,000feet) have ranged in thickness measuring from 10 to 20 feet while others have overlapped the lava flows of Shira and Mwanzi in the east and west. Lahars of Kibo also vary in thickness exceeding 100 feet in some regions and these along with the lava flows of Kibo. Downie et al (1972) suggested that Kibo’s activity was separated by long periods of dormancy which have got even longer with each eruption, therefore signifying that the present day dormancy of Kilimanjaro could yet again be another lengthily period of dormancy before any activity takes place. According to studies, the volume of lava has decreased with each eruption.

Kilimanjaro’s main phase of activity according to Downie et al (1972) was in the Pleistocene while there have been legends from the Wachagga tribes living on the flanks of the volcano of an eruption on Kibo just over 200 years ago.

Kilimanjaro goes threw various environments roughly 3,300 feet apart as it increases with altitude. A high density of population below 6000 feet to the base of the mountain occupies the land and uses it for agriculture. Forests containing various wildlife and plant species (e.g. Ferns and Heather) occupy the land from 6,000 feet to about 13,000 feet and receive the largest amount of precipitation. The environment gradually turns into semi-desert containing very little species and is largely dominated by lichens, before reaching the summit where arctic conditions prevail.

Source: Nationalgeographic

Lava tower (Source: summitpost.org)

Lava tower (Source: www.point-blue.com)

(Source: kilimanjaroexpeditions.files.wordpress.com)