Plate data: Bird (2003), PB2002, converted by Hugo Ahlenius, Nordpil (ODC-By 1.0). Land: Natural Earth (India POV).
The Scotia Plate is an oceanic plate between the southern tip of South America and the Antarctic Peninsula. Bird (2003) calls it the mid-sized Scotia plate: it largely coincides with the Scotia Sea and is bounded by the South American Plate on the north and the Antarctic Plate on the south and west, except locally where it meets the small Shetland Plate. On this map, Cape Horn sits on its western end.1
To the east, the small Sandwich Plate is a volcanic arc and forearc block. The East Scotia Ridge spreading center separates it from the Scotia Plate, and the South Sandwich Trench separates it from the South American Plate. Bird digitized the shape of the East Scotia Ridge from published surveys.
The Shetland Plate on its southwestern side is newer still. Back-arc spreading in the Bransfield Basin, southeast of the South Shetland Islands arc, split it off from the Antarctic Plate. Pelayo and Wiens located about 34 moderate earthquakes in this area, and there are three active volcanoes in the South Shetland arc.
Most of this part of PB2002 comes from Pelayo and Wiens (1989), who relocated earthquakes in the region and worked out how its plates move. Because published maps of the area were small and distorted, Bird traced its boundaries on ETOPO5 seafloor depth data. He drew the South American-Scotia boundary south of South Georgia Island, where earthquakes are more common, including a magnitude 5.9 event in 1965.
The region has changed recently in geologic terms. Before about 4 million years ago, a small Phoenix (or Drake) plate lay between Tierra del Fuego and the Antarctic Peninsula. It later became welded to the Antarctic Plate. Its long boundaries with the South American and Antarctic Plates now mix transform, convergent and short spreading sections, as the table below shows.2
Scotia Plate in numbers
Measured from its PB2002 outline, the Scotia Plate covers about 1.7 million km², or 0.3% of the
Earth's surface. That makes it number 19 by area of the 52 plates in the model.
It spans from 62°S to 52°S and from 76°W to 28°W.
Its edge is about 7,723 km long, mostly convergent:
19.1%divergentDivergent boundary. Plates pull away from each other and new crust forms between them. Source (1,472 km)
, 42.6%convergentConvergent boundary. Plates move toward each other and crust is destroyed as one plate dives under another. Source (3,290 km)
and 38.3%transformTransform boundary. Plates slide horizontally past each other. Crust is neither made nor destroyed. Source (2,961 km)
.
Along its boundaries it moves a mean 1.6 cm/yr relative to its neighbors, fastest against the Sandwich Plate. Bird (2003)
Neighboring plates Neighbors. Plates that share a boundary with this plate. Most plate movement happens along these narrow zones between plates. Source
The Scotia Plate shares a boundary with 4 plates in PB2002, longest shared edge first.
The longest, about 3,429 km, is with the South American Plate; the shortest, about 214 km, is with the Shetland Plate.
