The Afar depression, also called the Afar triangle, or even Danakil or Dancalie, from the name of its northern region, located below sea level, is a depression located in East Africa, at the junction between the Great Rift Valley, to the southwest, the Red Sea to the north and the Gulf of Aden to the east.
With an area of approximately 4000 km² (100 km × 40 km) for its part below the global level of the oceans, the Afar depression is located mainly in eastern Ethiopia, but also covers central Eritrea, southern Djibouti and extreme. northwest of Somalia.
Reaching 155 meters below sea level in Lake Assal and bordered by mountains and cliffs peaking at more than 4,000 meters above sea level, the Afar depression is in the form of a large triangular collapse whose altitude decreases towards the north. and east. It is connected to the Great Rift Valley to the southeast, the Gulf of Aden through the Gulf of Tadjourah to the east, and the Red Sea to the north. the north and forms a series of salt lakes, including Lake Abbe, the largest in the region.
This depression constitutes a triangular graben limited to the northeast by the Danakil block and to the west and south by the Ethiopian plateaus, which constitute traps. From the center radiate three major stretches of the Earth's crust: a rift that runs to the southwest and forms the valley of the great rift, a rift that extends across a ridge in the Gulf of Aden through the Gulf of Tadjourah to the east, and a third rift that spans another ridge in the Red Sea to the north. This tectonic configuration means that the Danakil bloc, a horst located in northern Djibouti and southern Eritrea, is part not of the African plate, but of the Arabian plate and moves away from the rest of Africa, remaining linked to Arabia, off Yemen. This region is one of only two places in the world with Iceland where it is possible to observe an emerging breach. The area is seismically active with the presence of normal faults causing relatively small earthquakes. On the other hand, volcanism is very active there with the presence of numerous red volcanoes emitting fluid lavas, usually basaltic, during effusive eruptions, including Erta Ale - which contains a more or less permanent lava lake - , the Dallol and its concretions and hot springs, and the Ardoukôba, whose first and last eruption dates back to 1978.