Erta Ale is 613 metres (2,011 ft) high, with one or sometimes two
active lava lakes at the summit which occasionally overflow on the
south side of the volcano. It is notable for holding the
longest-existing lava lake, present since the early years of the
twentieth century (1906). Volcanoes with lava lakes are very rare:
there are only eight in the world. Erta Ale means "smoking mountain"
in the local Afar language and its southernmost pit is known locally
as "the gateway to Hell". In 2009, it was mapped by a team from the
BBC using three-dimensional laser techniques, in order for the
mapping team to maintain a distance and avoid the lakes' searingly
hot temperatures. Erta Ale is centered over the East African Rift
system, which is a triple junction setting whose movements are
resulting in the formation of a pull-apart basin or rift. The
volcano comprises mainly mafic material which has been brought up to
the surface caused by unroofing of the mantle due to this rift
formation. There was a major eruption on 25 September 2005 which
killed 250 head of livestock and forced thousands of nearby
residents to flee. There was further lava flow in August 2007,
forcing the evacuation of hundreds and leaving two missing. An
eruption on 4 November 2008 was reported by scientists at Addis
Ababa University.Another eruption was reported in January 2017.
**Source: Wikipedia