Other worlds
Erta Ale is a continuously active basaltic shield volcano in Ethiopia's Danakil Depression. What makes it a destination for planetary scientists is the persistent lava lake in its summit caldera, one of only a handful on Earth. This lake of molten rock is a natural laboratory and an analog for volcanic processes on other planets and moons. The low-silica basaltic magma is a close match for the lavas believed to have formed the vast volcanic plains of Venus and the fiery landscapes of Jupiter's moon, Io.
Io is the most volcanically active body in the solar system, and studying Erta Ale's lava lake dynamics—how the crust forms, fractures, and sinks—shows the physical processes on Io's surface. The lake's surface often forms a dark, solid crust that is torn apart by the movement of the underlying magma, showing incandescent lava in a process of constant renewal. This activity helps scientists model the heat transfer and crustal mechanics that may occur on a global scale on other worlds. The lava temperature can reach up to 1200°C, providing a valuable model for the high-temperature volcanism suspected on Io.
The smoking mountain
Located at the Afar Triple Junction, where three tectonic plates are pulling apart, Erta Ale rises 613 meters (2,011 feet) above the surrounding desert. Its name means "Smoking Mountain" in the local Afar language. The summit caldera is an elongated oval, measuring approximately 1.6 by 0.7 kilometers. Within this caldera are two main pit craters; the southern one contains the most persistently active lava lake.
The existence of this lava lake has been documented since at least 1906, making it the longest-known continuously active lava lake in the world. Its stability is due to a direct connection to a shallow magma chamber and a delicate balance of heat loss at the surface and heat supplied from below through convection. The surface is a dynamic system of cooling crustal plates and fountains of lava that can spew molten rock up to 13 feet high. Eruptions from fissures on the volcano's flanks are also common, with significant lava flows recorded in 2005 and 2017.