During the next one million years, the 
Ethiopian rift will extend from the Red 
Sea to the Indian Ocean. When it does, 
the Horn of Africa will become a new 
continent. (Image courtesy of NASA)
Last September, the ground in part of northern Ethiopia suddenly dropped 10 feet and split apart so quickly that the gaping hole swallowed camels and goats. Over the next three weeks, the earth quaked 160 times, opening up a 25-foot-wide crack a third of a mile long.
Using satellite radar data, Tim Wright, a geophysicist at the University of Leeds in England, has pieced together exactly how the gap got started. As the African and Arabian tectonic plates drift apart, the crust between them weakens. "Magma forming at the base of the crust periodically drips up, like a lava lamp, and pools in a chamber—like a balloon slowly inflating," Wright says. "When the balloon reaches a critical pressure, it pops." That pop caused a contained volcanic explosion, injecting molten rock into a 35-mile-long elongated bubble just a few miles underground and forcing a crack in the surface above.
As the plates continue to drift apart, tension increases until the whole process happens again. "Eventually, we think it will connect to the Red Sea, and water will flood in," says Wright.