Why these volcanic hot springs in Ethiopia are neon yellow

About 600 km north of Ethiopia’s capital Addis Ababa, the district of Dallol paints a rather curious picture. The former mining settlement harbours a tiny population, last published in 2007 by the country’s Central Statistical Agency as 83,930, and it holds the current record for the highest average temperature of any inhabited place on Earth. Between 1960 and 1966, the average annual temperature was a toasty 35°C (96°F), but the temperature can regularly creep to over 46°C (115°f).

It’s also home to the incredible Dallol Volcano. At 48 metres below sea level, Dallol is Earth's lowest land volcano, and its last recorded eruption was in 1926. Its craters contains hot springs that boast a whole range of otherworldly colours - including neon yellow - thanks to the hot magma bubbling below the surface. This magma heats the groundwater that flows into the area from the nearby highlands, and as the heated groundwater moves up towards the surface, it dissolves salt, sulphur, potash and other minerals and deposits them in the Dallol craters.

"The supersaturated brine emerges through hot springs in the floor of the craters,” says Hobart King at Geology.com. "As the brines evaporate in the hot arid climate, extensive salt formations are formed on the floor of the craters. These are coloured white, yellow, brown, orange and green by sulfur, dissolved iron, mud and the life activity of halophile algae."

It might look incredible, but Dallol poses quite a challenge to the stream of tourists that brave it every year. If they can stand the heat, there’s always the threat of acid pools and deadly gases to keep them on their toes: "Dallol craters are dangerous places to visit because their surface can be covered by a crust of salt with pools of hot acid water just inches below,” says King. "Toxic gases are sometimes released from craters."

Take a tour of this place that's truly unlike anywhere else on Earth:

Source: Geology.com