Aden Ridge in the context of "Arabian plate"

The Gulf of Aden (Arabic: خليج عدن; Somali: Gacanka Cadmeed) is a deepwater gulf of the Indian Ocean between Yemen to the north, the Arabian Sea to the east, Djibouti to the west, and the Guardafui Channel, the Socotra Archipelago, Puntland in Somalia and Somaliland to the south. In the northwest, it connects with the Red Sea through the Bab-el-Mandeb strait, and it connects with the Arabian Sea to the east. To the west, it narrows into the Gulf of Tadjoura in Djibouti. The Aden Ridge lies along the middle of the gulf, and tectonic activity at the ridge is causing the gulf to widen by about 15 mm (0.59 in) per year.

The ancient Greeks regarded the gulf as one of the most important parts of the "Erythraean Sea". It later came to be dominated by Muslims, as the area around the gulf converted to Islam. From the late 1960s onwards, there was an increased Soviet naval presence in the Gulf. The importance of the Gulf of Aden declined while the Suez Canal was closed, but it was revitalized when the canal was reopened in 1975, after being deepened and widened by the Egyptian government.

The Red Sea Rift is a mid-ocean ridge between two tectonic plates, the African plate and the Arabian plate. It extends from the Dead Sea Transform fault system, and ends at an intersection with the Aden Ridge and the East African Rift, forming the Afar triple junction in the Afar Depression of the Horn of Africa.

The Red Sea Rift was formed by the divergence between the African and Arabian plates. The rift transitioned from a continental rift to an oceanic rift. Magnetic anomalies suggest that the spreading rate on either side of the Red Sea is about 1 cm/year. The African plate has a rotation rate of 0.9270 degrees/Ma (million years), while the Arabian plate has a rotation rate of 1.1616 degrees/Ma.

The Afar triple junction is a triple junction located along a divergent plate boundary dividing the Nubian, Somali, and Arabian plates. This area is considered a present-day example of continental rifting leading to seafloor spreading and producing an oceanic basin. Here, the Red Sea Rift meets the Aden Ridge and the East African Rift. The latter extends a total of 6,500 kilometers (4,000 mi) from the Afar Triangle to Mozambique.

The connecting three arms form a triple junction. The northernmost branching arm extends north through the Red Sea and into the Dead Sea, while the eastern arm extends through the Gulf of Aden and connects to the Mid-Indian Ocean ridge further to the east. Both of these rifting arms are below sea level and are similar to a mid-ocean ridge.

The Owen fracture zone (OFZ), though misnamed as a fracture zone, is a transform fault in the northwest Indian Ocean that separates the Arabian and African plates from the Indian plate. Extending north-northeast from where the Carlsberg Ridge meets the Sheba ridge in the south to the Makran Subduction Zone in the north, it represents the port side of the northward motion of the Indian subcontinent during the Late Cretaceous–Palaeogene break-up of Gondwana. Slip along the Owen fracture zone is occurring at 2 mm (0.079 in)/yr, the slowest rate on Earth, which means the Arabian plate moves northward faster than the Indian plate (4 vs. 2 mm/yr).

In some usages, the name Owen Transform Fault is used to denote the short section between the end of the Aden-Sheba ridge and the Carlsberg Ridge. Additionally, this area has been called the Aden–Owen–Carlsberg triple junction, although the Carlsberg Ridge is offset 330 km (210 mi) from the point where the Owen fracture zone/fault intersects the Sheba segment of the Aden Ridge.