The Smoking Mountain
Erta Ale is a 613-meter-high basaltic shield volcano in the Afar Region of Ethiopia. Its name translates to "Smoking Mountain" in the local Afar language, a fitting title for Ethiopia's most active volcano. It is located in the Danakil Depression, a desert that is one of the hottest and lowest places on the planet. The volcano rises from a landscape that is, in places, below sea level.
The volcano's summit caldera measures approximately 1.7 by 0.6 kilometers and contains several pit craters. At least one of these craters holds a persistent lava lake, a rare natural sight. The lake of molten rock has been active for over a century, with observations dating back to at least 1906. This makes it the longest-existing lava lake known on Earth. The lava is basaltic, a composition low in silica that allows it to remain fluid and form a lake. The surface often appears as a dark, shifting crust, broken by incandescent lines of magma from below.
A Tectonic Triple Junction
Erta Ale's constant activity is a direct result of its location. It sits within the Afar Triple Junction, a point where three of Earth's tectonic plates (the African, Somali, and Arabian plates) are actively pulling apart. This continental rifting process, part of the larger East African Rift system, thins the Earth's crust and allows magma from the mantle to ascend to the surface.
The lava lake is sustained by a process called magmatic convection. Hot, gas-rich magma rises from a shallow chamber, releases its gases at the surface, and then cools. As it cools, the magma becomes denser and sinks back down along the crater walls, creating a continuous, circulating flow that keeps the lake in a liquid state. This shows scientists volcanic processes of volcanic processes that normally occur deep underground. By studying the chemistry of the lava and the gases released, researchers can learn about the composition of the Earth's mantle. Major eruptions have occurred, such as one on September 25, 2005, which killed 250 heads of livestock and forced thousands of residents to evacuate.