Our fingernails grow about 0.6 inches per year. The shelves of continental crusts spread apart at about the same rate.
Ethiopia is the only place on the planet where we can see a continent splitting apart on dry land.
In September 2005, hundreds of deep crevices appeared within a few weeks, and parts of the ground shifted more than 25 feet, almost overnight. More than one half a cubic mile of rising molten rock – magma – had seeped into a crack between the African and Arabian tectonic plates, forcing them further apart.
The Red Sea could shift and the horn of Africa could break off from the continent to become an island – in a million years! [Science blog]