Thought the "Seven Seas" were static? Nope, they've gone through many incarnations since the ancient Greeks started grouping their local bodies of water into one convenient moniker. European explorers expanded the definition a bit to include a wider sampling of world waters, and today we'd probably list the Arctic, North and South Atlantic, North and South Pacific, Indian and Southern Oceans in the big seven -- if we used the phrase at all.
But it turns out, there's a new ocean in the making, rending the African continent right through the middle of Ethiopia. In 2005, a rift opened up 35 miles (56 kilometers) of land in a mere two days. At the time, geologists suspected this might be the start of a new ocean, but until recently, that was a contested claim.
A new study in Geophysical Research Letters confirms that the volcanic processes that caused the Ethiopian rift to break so suddenly are almost exactly like those that occur at the bottom of the seabed. The study's leader, Atalay Ayele, a professor at Addis Ababa University, gathered seismic data on the 2005 rift event, combining it with data from Eritrea and Yemen. He was able to reconstruct what happened: A volcano called Dabbahu erupted, forcing magma through the rift and ripping apart the land a gaping 20 feet (6 meters) wide.
The research is useful for people who live near such volcanic rifts, but it also shows us something of a process that we can't really see otherwise. It's hard to monitor seafloor ridges because they're, well, under the ocean. The Ethiopian rift offers a potential test case in seafloor spreading and the formation of ocean basins -- albeit one that's aboveground and easy to keep tabs on.
And we're already learning about how such rifts can act: According to Science Daily, the new research showed that "highly active volcanic boundaries along the edges of tectonic ocean plates may suddenly break apart in large sections, instead of little by little as has been predominantly believed." It sounds like the difference of cutting a rope in half instead of snipping away at its individual fibers.
As for the new Ethiopian sea, oceans aren't made in a day. Cindy Ebinger, a professor of Earth and environmental sciences at the University of Rochester who co-authored the study, has been keeping tabs on the area's seismic activity. To date there have 12 similar seismic events -- none of which have been very big.