Where am ILOCATED

Somali Plate

The Somali Plate is the 8th-largest of the 52 plates in the PB2002 plate model, covering 19.2 million km² (7.4 million sq mi), or 3.8% of Earth’s surface. East Africa beyond the East African Rift, including Kenya, Somalia, most of Tanzania and Madagascar, and the western Indian Ocean floor.

Somali Plate on the globe, with its boundaries coloured by typeSomali PlateAfrican PlateIndian PlateArabian Plate
Somali Plate Convergent Divergent Transform
Area
19.2 million km² (7.4 million sq mi)
Share of Earth’s surface
3.8%
Speed across the plate
1.7 to 3.6 cm a year (0.7 to 1.4 in)
Direction at its center
Toward the east-northeast
Length of its edges
23,440 km (14,570 mi)
Neighboring plates
5
Edges by type
9% convergent · 59% divergent · 32% transform
Volcanoes on it
49 active in the past ~12,000 years
What plate am I on?All tectonic plates

What happens at its edges

It is slowly separating from the African (Nubian) Plate along the East African Rift, by only a few millimeters a year. The rift is one of the few places where a continent can be seen in the early stages of splitting apart.

Elsewhere it is bordered by spreading ridges in the Indian Ocean, against the Indian, Australian, Antarctic and Arabian plates.

How fast it moves, and which way

At its center (13.1°S, 48.4°E) the Somali Plate moves about 2.8 cm (1.1 in) a year toward the east-northeast. Because a plate turns around a pole rather than sliding in a straight line, the speed changes across it: from 1.7 cm (0.7 in) a year to 3.6 cm (1.4 in) a year, with an area-weighted average of 2.8 cm a year. That average makes it the 35th fastest of the 52 plates.

These figures are measured against the average motion of all the plates together (the “no-net-rotation” frame), which is how plate speeds are usually quoted. Measured against the African Plate instead, the Somali Plate moves about 0.3 cm (0.1 in) a year toward the southeast at its center.

In the model it rotates about a pole at 49.0°N, 93.9°W at 0.341° per million years. The speeds are averages over years to millions of years of measurement; earthquakes move the ground near a boundary in sudden steps instead.

Neighboring plates and boundaries

Its edges run for 23,440 km (14,570 mi): 9% convergent, where plates move together; 59% divergent, where they move apart; and 32% transform, where they slide past each other.

NeighborShared edgeBoundary typesRelative speed
African Plate9,040 km (5,620 mi)Divergent 55% · Transform 23% · Convergent 23%0.3 cm a yearup to 0.6 cm
Antarctic Plate5,520 km (3,430 mi)Divergent 59% · Transform 41%1.2 cm a yearup to 1.4 cm
Indian Plate3,820 km (2,370 mi)Divergent 65% · Transform 32%3.0 cm a yearup to 3.6 cm
Australian Plate3,150 km (1,950 mi)Divergent 56% · Transform 44%4.0 cm a yearup to 5.0 cm
Arabian Plate1,920 km (1,190 mi)Divergent 67% · Transform 33%2.4 cm a yearup to 2.8 cm

Relative speed is how fast the two plates move against each other along their shared edge, averaged over its length.

Countries and territories on the Somali Plate

9 lie entirely on it; the other 13 are split between plates. The share is the part of each country’s land on this plate.

Volcanoes on the Somali Plate

The Smithsonian Global Volcanism Program lists 49 volcanoes on this plate that have been active in roughly the past 12,000 years. The most recent eruptions on record:

Sources

Outline, area, boundary types and motion: Bird, P. (2003), An updated digital model of plate boundaries, Geochemistry Geophysics Geosystems, 4(3), 1027, doi:10.1029/2001GC000252. Released by its author into the public domain (CC0 1.0). Areas are the model’s published figures; speeds, directions, boundary lengths and countries are calculated from its outlines, boundary steps and rotation poles.

Volcanoes: Global Volcanism Program, Smithsonian Institution, Volcanoes of the World (v. 5.4.0). Country outlines: Natural Earth.