In September 2005, a 35-mile fissure unexpectedly split the earth in northeast Ethiopia’s Afar Depression, a region already known for its extreme geological activity. The rift, which reached up to 25 feet wide, opened over a matter of days, representing a dramatic and rapid geological shift.
“We had never seen something like this,” Cynthia Ebinger, a geologist at Tulane University, told Popular Mechanics in 2023. “This kind of thing happens regularly on the seafloor, but it was the first known example on land.” The event, now known as the Dabbahu Fissure, occurred amidst volcanic eruptions and hundreds of earthquakes, and released pressure equivalent to 400 years of tectonic movement in just a few days, according to Ebinger.
The Afar Depression sits at the Afar Triple Junction, where the Arabian, Nubian, and Somali tectonic plates are pulling apart. This junction is part of the larger East African Rift System (EARS), a network of rifts and valleys stretching from Jordan to Mozambique. The EARS is approximately 25 million years in the making and comprises two main branches: the Eastern Rift Valley and the Western Rift Valley. The Afar Depression, still, is the most geologically active part of the system, characterized by high magma production and numerous volcanoes.
According to the Wikipedia entry for the Afar Triangle, the region contains the lowest point in Africa, Lake Assal in Djibouti, which sits 155 meters (509 feet) below sea level. The Awash River is the primary water source, but it dries up during the annual dry season, forming a series of saline lakes.
Scientists believe that a mantle plume of magma beneath the Afar Depression is driving the rifting. This plume pushes hot rock towards the surface, creating pressure that eventually leads to fissures like the Dabbahu Fissure. Following the initial 2005 event, thirteen similar, though less severe, rifting episodes occurred over the next five years before the plates returned to their normal rate of movement.
Ebinger predicts that similar dramatic episodes will continue to occur, potentially every 50 to 100 years. As the land continues to split, the Afar Depression is expected to sink further, a process similar to seafloor spreading. In approximately 500,000 years, the depression could fall below sea level and become flooded, potentially creating a new sea.
The future of this new sea remains uncertain. While the rifting could eventually split the African continent into two, the rate of separation decreases moving south. It’s possible that only a wedge of seawater will intrude. Not all continental rifts result in the formation of new oceans, as demonstrated by North America’s Midcontinental Rift (MCR), a 1,800-mile rift that cracked open over a billion years ago but ultimately failed to become an ocean.
The Dabbahu Fissure’s long-term fate is therefore unclear. Scientists have also discovered areas of molten rock extending far from the rift itself, a finding that challenges conventional geological understanding. The possibility remains that the rifting process could halt, similar to the MCR.
