Somali Plate
The Somali Plate or Somalian Plate is a tectonic plate that is being formed as the African Plate
African Plate
The African Plate is a tectonic plate which includes the continent of Africa, as well as oceanic crust which lies between the continent and various surrounding ocean ridges.-Boundaries:...

 is splitting along the East African Rift
East African Rift
The East African Rift is an active continental rift zone in eastern Africa that appears to be a developing divergent tectonic plate boundary. It is part of the larger Great Rift Valley. The rift is a narrow zone in which the African Plate is in the process of splitting into two new tectonic plates...

. The part of the African Plate which lies on the other side of the rift is sometimes referred to as the Nubian Plate. As the rifting is, in geologic terms, just getting underway, these two parts of the African Plate are generally regarded as protoplates rather than as full-fledged independent plates.

The Somali Plate is bounded on the west by the East African Rift, which extends south through East Africa
East Africa
East Africa or Eastern Africa is the easterly region of the African continent, variably defined by geography or geopolitics. In the UN scheme of geographic regions, 19 territories constitute Eastern Africa:...

 from the triple junction
Triple junction
A triple junction is the point where the boundaries of three tectonic plates meet. At the triple junction a boundary will be one of 3 types - a ridge, trench or transform fault - and triple junctions can be described according to the types of plate margin that meet at them...

 in the Afar Depression
Afar Depression
The Afar Triangle is a geological depression that is caused by the Afar Triple Junction which is part of the Great Rift Valley. It overlaps Eritrea, Djibouti and the entire Afar Region of Ethiopia. The Afar Triangle includes the Danakil Depression and the lowest point in Africa, Lake Asal...

, and an undersea continuation of the rift extending southward offshore. The northern boundary is the Aden Ridge
Aden Ridge
The Aden Ridge is a divergent tectonic plate boundary which runs offshore in the Gulf of Aden and Indian Ocean along the southeastern coastline of the Arabian Peninsula. It extends eastward from the Afar Triple Junction to a junction with the Owen Fracture Zone, and separates the Arabian Plate...

 along the coast of Saudi Arabia
Saudi Arabia
The Kingdom of Saudi Arabia , commonly known in British English as Saudi Arabia and in Arabic as as-Sa‘ūdiyyah , is the largest state in Western Asia by land area, constituting the bulk of the Arabian Peninsula, and the second-largest in the Arab World...

. The eastern boundary is the Central Indian Ridge
Central Indian Ridge
The Central Indian Ridge is a divergent tectonic plate boundary between the African Plate and the Indo-Australian Plate, traversing the western regions of the Indian Ocean...

, the northern portion of which is also known as the Carlsberg Ridge
Carlsberg Ridge
The Carlsberg Ridge is the northern section of the Central Indian Ridge, a divergent tectonic plate boundary between the African Plate and the Indo-Australian Plate, traversing the western regions of the Indian Ocean....

. The southern boundary is the Southwest Indian Ridge
Southwest Indian Ridge
The Southwest Indian Ridge is a divergent tectonic plate boundary located along the floor of the southwest Indian Ocean. It separates the African Plate to the north from the Antarctic Plate to the south....

. Dating of volcanism in the Comoro Islands
Comoro Islands
The Comoros Islands form an archipelago of volcanic islands situated off the south-east coast of Africa, to the east of Mozambique and north-west of Madagascar. They are divided between the sovereign state of Comoros and the French overseas department of Mayotte...

 and northern Madagascar
The Republic of Madagascar is an island country located in the Indian Ocean off the southeastern coast of Africa...

2. Bedrock3. Conduit 4. Base5. Sill6. Dike7. Layers of ash emitted by the volcano8. Flank| 9. Layers of lava emitted by the volcano10. Throat11. Parasitic cone12. Lava flow13. Vent14. Crater15...

s indicates a rate of motion to the east over a hotspot
Hotspot (geology)
The places known as hotspots or hot spots in geology are volcanic regions thought to be fed by underlying mantle that is anomalously hot compared with the mantle elsewhere. They may be on, near to, or far from tectonic plate boundaries. There are two hypotheses to explain them...

of approximately 45 mm/yr.
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