Photos of the Alid volcanic center

View of Alid volcanic center from the west, across alluvial pediment shed from the Precambrian Eritrean highlands. Alid is a structural dome and rhyolitic volcanic center that rises about 700 m from the floor of the Danakil Depression, an actively spreading graben that extends north from the Afar triple junction. The summit of Alid is 910 masl.

View of the western portion of the summit basin of Alid volcanic center (looking from the east). The western crater rim is covered with buff-colored pumice, created during the last major pyroclastic eruption from Alid, some 23,000 years ago. Just in front of the far rim is an arcuate lava flow erupted just after the pumice was deposited. The summit basin is believed to have formed initially due to structural collapse associated with doming, but was likely enlarged during the pyroclastic eruptions. The summit area of Alid receives more rainfall than the surrounding Danakil lowlands, and supports limited grazing of cows and goats.


An acid thermal pool, about 1 meter across, at Ilegedi. Water in these pools varies from the ambient air temperature (~30-40°C) to over 80°C, due to mixing with the hot fumarolic condensate.

Ilegedi is in a short N-S valley just east of the eastern edge of the summit depression. It is the major water source on Alid and is used by humans and their stock (camels, goats and burros) as well wildlife such as birds and babboons.


Theoderos Tesfai, an Eritrean geochemist, collects a sample of fumarolic gas at As'ela, a fumarole on Alid's north flank. He is watched by a local goatherder.

Fumaroles are found at about ten sites in the summit depression and north flank of Alid. The ground surface contains efflorescent salts such as alum, a hydrated potassium sulfate, tschermigite, a hydrated ammonium sulfate, gypsum and clays such as illite and montmorillonite.

The fumaroles emit steam as well as about 5% other gases such as carbon dioxide, hydrogen, hydrogen sulfide, nitrogen, and ammonia.

 

 


Windscorpion, about 7 cm from tip to tip, found at campsite on the plain west of Alid. These arachnids have lungs and move about very quickly relative to their scorpion and spider cousins. Evidently, they are not usually poisonous. This specimen was released a "safe" distance from camp.

More Photos (Boya Well)


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