Thought this might be of some interest:
“The crack is the surface component of a continental rift forming as the Arabian and African plates drift away from one another. It began to open up in September 2005, when a volcano at the northern end of the rift, called Dabbahu, erupted.”
And it happened in a few days, apparently.
“…Ebinger says it could continue to widen and lengthen. “As the plates keep spreading apart, it will end up looking like the Red Sea,”‘
Possibly in 4 million years.