The Red Sea rift and Bab-el-Mandeb
The long narrow Red Sea is a crack where Africa and Arabia are pulling apart, closed at the south by the Gate of Grief.
Why is there a long, narrow sea there?
It looks odd on the map: a thin finger of water about 1,400 miles long and at most about 220 miles wide, running between Africa and the Arabian Peninsula. That is because the Red Sea is a rift, a crack in the Earth's crust. The Arabian plate is pulling away from the African plate, about a centimeter a year, roughly as fast as fingernails grow.
Starting some 25–30 million years ago, Arabia began tearing away from Africa. The gap sank and filled with sea. Hot new crust rises along the middle, so in many millions of years the Red Sea may widen into an ocean, the way the Atlantic once began.
At its southern end, in the Afar region of Ethiopia and Djibouti, three rifts meet (the Red Sea, the Gulf of Aden and the East African Rift), one of the few places on land where you can watch a new ocean being born, with volcanoes and earthquakes.
Bab-el-Mandeb
The southern mouth of the Red Sea is the strait of Bab-el-Mandeb, Arabic for "Gate of Grief" (or Gate of Tears), named for how dangerous it was to sail. It is about 20 miles wide at its narrowest, between Yemen and Djibouti/Eritrea. Every ship using the Suez Canal to or from Asia must pass through it, which is why it matters so much for trade and security today.
Key facts
- The Red Sea is a rift where the Arabian plate pulls away from Africa, about 1 cm a year
- Afar, in Ethiopia and Djibouti, is where three rifts meet
- Bab-el-Mandeb means Gate of Grief; about 20 miles wide