The two plates in Ethiopia moved apart by 26 feet (8 meters). As they did so, 0.6 cubic mile (2.5 cubic kilometers) of magmaenough to fill more than 2,000 football stadiumswas injected into a vertical crack known as a dyke.
Above the dyke, faults moved by several meters and fissures opened up in Earth's surface.
More than 160 earthquakes were detected in the area during this time. Some 10,000 local people were displaced, and several camels and goats fell into the open fissures.
But it is the process of magma intrusion into the gap, rather than the cracking of the crust, that is responsible for controlling plate spreading in these settings.
"The process is very similar to the way the crust grows at mid-ocean ridges, such as the one running along the center of the Atlantic Ocean," Wright said.
Gezahegn Yirgu, a co-author of the study, says the September rift is a reminder of the awesome geological changes taking place on Earth.
"The event was a vivid expression of the unimaginable amount of stored energy the Earth releases from time to time to split apart continents," said Yirgu, who is an earth scientist at the University of Addis Ababa in Ethiopia.
The tectonic plates are moving apart at about the same speed that fingernails grow (a few centimeters per year).
"We don't know if an ocean will eventually be formed here, but the prospects are good," Wright said. "It just may take a million years before the port can be built."
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