The Danakil Depression: The Hottest Place on Earth

What Happens When Tectonic Plates Move Apart

Danakil Depression
The Danakil desert region of Ethiopia, home to some of the most hellish terrains and regions on planet Earth. Ji-Elle, Wikimedia Commons

Deep in the horn of Africa is a region called the Afar Triangle. This desolate, desert regions is the home of the Danakil Depression, a place that seems more alien than Earth-like. It's the hottest place on Earth and during the summer months, it can get up to a high of 55 degrees Celsius (131 degrees Fahrenheit) thanks to geothermal heat. Danakil is dotted with lava lakes that bubble inside the volcanic calderas of the Dallol area, and hot springs and hydrothermal pools permeate the air with the distinct rotten-egg smell of sulfur. The youngest volcano, called Dallol, is relatively new. It first erupted in 1926. The whole region is more than 100 meters below sea level, making it one of the lowest places on the planet. Amazingly, despite its toxic environment and lack of rainfall, it's home to some lifeforms, including microbes. 

What Formed the Danakil Depression?

Danakil Depression
A topographical realization of the Afar Triangle and the Danakil Depression within it. Wikimedia Commons

This region of Africa, which spans about 40 by 10 kilometers and is bordered by mountains and a high plateau, formed as Earth basically pulled apart at the seams of plate boundaries. It's technically called a depression ​and was formed when three tectonic plates underlying Africa and Asia began moving apart millions of years ago. At one time, the region was covered by ocean waters, which laid down thick layers of sedimentary rock and limestone. Then, as the plates moved further apart, a rift valley formed, with the depression inside. Currently, the surface is sinking as the old African plate splits into the Nubian and Somali plates. As this happens, the surface will continue to settle down.

Notable Features in the Danakil Depression

Danakil Depression
A NASA Earth Observing Systems view of the Danakil Depression from space. Several of the largest features, including Gada Ale volcanoe, and two lakes, are visible. NASA

For such an extreme place, Danakil also has some extreme features. There's a large salt dome volcano called Gada Ale that measures two kilometers across and has spread lava around the region. Nearby bodies of water include a salt lake, called Lake Karum, 116 meters below sea level, and another very salty (hypersaline) lake called Afrera. The Catherine Volcano, a shield volcano, has been around for just under a million years, covering the surrounding desert area with ash and lava. There are also major salt deposits in the region. The Afar people mine it and transport it to nearby cities for trade via camel routes.

Life in the Danakil

Danakil Depression
Hot springs in the Danakil region offer access to mineral-rich waters that support extremophile life forms. Rolf Cosar, Wikimedia Commons

The hydrothermal pools and hot springs in this region are teeming with microbes. Such organisms are called "extremophiles" because they not thrive in extreme environments, like the inhospitable Danakil Depression. These extremophiles can withstand high temperature, toxic volcanic gases in the air, high metal concentrations in the ground, as well as high saline and acid content. Most extremophiles in the Danakil Depression are extremely primitive, prokaryotic microbes, some of the most ancient lifeforms on our planet. 

As inhospitable as the environment is around Danakil, it seems that this area played a role in the evolution of humanity. In 1974, researchers led by paleoanthropologist Donald Johnson found the fossil remains of an ​Australopithecus woman nicknamed "Lucy". The scientific name for her species is "australopithecus afarensis" as a tribute to the region where she and fossils of others of her kind have been found. That discovery has led to this region being dubbed the "cradle of humanity".

The Future of Danakil

Danakil Depression
Volcanic activity continues in the Danakil Region as the rift valley widens. Iany 1958, Wikimedia Commons

As the tectonic plates underlying the Danakil Depression continue their slow movement apart (at about three millimeters a year), the land will continue to drop farther below sea level. Volcanic activity will continue as the rift created by the moving plates widens.

In a few million years, the Red Sea will come pouring into the area, extending its reach and perhaps forming a new ocean. For now, the region draws scientists to research the types of life that exist there and map the extensive hydrothermal "plumbing" that underlies the region. Inhabitants continue to mine salt. Planetary scientists are also interested in the geology and life forms here because they may hold clues to whether or not similar regions elsewhere in the solar system could also support life. There is even a limited amount of tourism that takes hardy travelers into this "hell on Earth."