Rift Fever: the day the continent of Africa splits in two

June 15, 2011– Eritrea — The first fracture appeared millions of years ago, resulting in the Red Sea and the Gulf of Aden. The second fracture, stretching south from Ethiopia to Mozambique, is known as the Great Rift Valley, and it is lined with several volcanoes. Millions of years from now, it too will be filled with seawater. But in the Danakil Depression, in the northern part of the valley, the ocean could arrive much sooner. There, low, 25 meter (82 foot) hills are the only thing holding back the waters of the Red Sea. The land behind them has already dropped dozens of meters from previous levels and white salt deposits on the desert floor testify to past encroachments of the sea. But lava soon choked off its access. For now, no one can really say when the sea will finally flood the desert. But when it does, it could go quickly. “The hills could sink in a matter of days,” Tim Wright, a fellow at the University of Leeds’ School of Earth and Environment, said at a recent conference hosted by the American Geophysical Union (AGU) in San Francisco. In the last five years, the geologic transformation of northeastern Africa has “accelerated dramatically,” says Wright. Indeed, the process is going much faster than many had anticipated. In recent years, geologists had measured just a few millimeters of movement each year. “But now the earth is opening up by the meter,” says Loraine Field, a scholar at the University of Bristol who also attended the conference.

Earth tremors cause deep fissures to form in the desert floor and the ground in East Africa is shattering like broken glass. Researchers in the Gulf of Tadjoura, which juts into Djibouti from the Gulf of Aden, have recently registered a barrage of seismic shocks. “The quakes are happening on the mid-ocean ridge,” Ebinger reports. Lava gushes out of fissures in these underwater mountain ranges to constantly create new earth crust — when it hardens; it becomes part of the sea floor. As the magma surges upward, it spreads the ocean floor on both sides, shifting tectonic plates and causing tremors. In recent months, the quaking in the Gulf of Tadjoura has been getting closer and closer to the coastline. As Ebinger explains, the splitting of the ocean floor will gradually extend to dry land. This is already the case along some fault lines in the Ethiopian desert, creating a geological spectacle that can otherwise only be witnessed deep below the surface of the ocean. Even the pattern of earthquakes supports the conclusion that the desert landscape is transforming into a deep seafloor, according to a recent article in the Journal of Geophysical Research published by Zhaohui Yang and Wang-Ping Chen, two geologists at the University of Illinois at Urbana-Champaign. The researchers have recorded several strong earthquakes at a shallow depth in northeastern Africa similar to ones that are otherwise only seen on mid-ocean ridges far out at sea. In recent months, researchers have also recorded an up-tick in volcanic activity. Indeed, geologists have discovered volcanic eruptions near the earth’s surface at 22 places in the Afar Triangle in northeastern Africa. Magma has caused fissures up to eight meters (26 feet) wide to open up in the ground, reports Derek Keir from the University of Leeds. While most of the magma remains beneath the surface, in places like Erta Ale it has made its way above ground. The eruption of the Nabro volcano is one more indication this process is accelerating. –Spiegel.de