Scotia Plate
The Scotia Plate is the 19th-largest of the 52 plates in the PB2002 plate model, covering 1.7 million km² (0.7 million sq mi), or 0.3% of Earth’s surface. The Scotia Sea between the tip of South America and the Antarctic Peninsula.
- Area
- 1.7 million km² (0.7 million sq mi)
- Share of Earth’s surface
- 0.3%
- Speed across the plate
- 0.9 to 1.6 cm a year (0.3 to 0.6 in)
- Direction at its center
- Toward the north-northeast
- Length of its edges
- 7,720 km (4,800 mi)
- Neighboring plates
- 4
- Edges by type
- 43% convergent · 19% divergent · 38% transform
- Volcanoes on it
- 1 active in the past ~12,000 years
What happens at its edges
It is bordered by the Scotia Arc, a loop of ridges and islands that includes South Georgia and the South Orkney Islands. Its long northern and southern edges are mostly sideways boundaries with the South American and Antarctic plates.
To the east lies the small Sandwich Plate, where Atlantic floor sinks beneath the volcanic South Sandwich Islands.
How fast it moves, and which way
At its center (57.3°S, 50.4°W) the Scotia Plate moves about 1.3 cm (0.5 in) a year toward the north-northeast. Because a plate turns around a pole rather than sliding in a straight line, the speed changes across it: from 0.9 cm (0.3 in) a year to 1.6 cm (0.6 in) a year, with an area-weighted average of 1.3 cm a year. That average makes it the 47th 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 South American Plate instead, the Scotia Plate moves about 0.5 cm (0.2 in) a year toward the east-northeast at its center.
In the model it rotates about a pole at 31.2°S, 99.6°W at 0.175° 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 7,720 km (4,800 mi): 43% convergent, where plates move together; 19% divergent, where they move apart; and 38% transform, where they slide past each other. The Antarctic Plate sinks beneath it.
| Neighbor | Shared edge | Boundary types | Relative speed |
|---|---|---|---|
| South American Plate | 3,430 km (2,130 mi) | Transform 52% · Convergent 40% · Divergent 8% | 0.5 cm a yearup to 0.5 cm |
| Antarctic Plate | 3,190 km (1,980 mi) | Convergent 53% · Transform 28% · Divergent 18% | 1.2 cm a yearup to 1.5 cm |
| Sandwich Plate | 890 km (550 mi) | Divergent 70% · Transform 30% | 7.3 cm a yearup to 8.1 cm |
| Shetland Plate | 210 km (130 mi) | Convergent 100% | 0.9 cm a yearup to 1.0 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 Scotia Plate
Each of these is split between plates. The share is the part of each country’s land on this plate.
- Chile about 3%
- Argentina under 1%
Volcanoes on the Scotia Plate
The Smithsonian Global Volcanism Program lists 1 volcano on this plate that has been active in roughly the past 12,000 years. The most recent eruptions on record:
- Fueguino Chile, 1820
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.