My Blogs (olelog) are mainly based on my daily reading of earth science news.
Here on whatonearth.olehnielsen.dk I try to weave some of the pieces together to a greater whole with added background info.
The north and south boundaries of the plate are transform fault boundaries. At the eastern margin the Scotia has a spreading boundary between it and the small Sandwich plate. The western boundary with the Antarctic plate is a complex and rather ill-defined boundary.
Image from USGS
The region near the Scotia Sea in the southern Atlantic Ocean is a complex area of marginal basins bordered by the South America and Antarctic plates. The boundary motion between these two larger plates is predominately strike-slip. The South America-Antarctic plate motion is left lateral at about 15 mm/yr, with the Scotia Plate twisting between the two. There does not appear to be any north-south compression of the Scotia Plate. However, pure strike-slip earthquakes do not represent all the motion between the Scotia Sea and Antarctic plates. Partitioning occurs on one or both of the Scotia Sea boundaries.
Beyond the eastern end of the Scotia Sea plate, the Sandwich Plate is moving rapidly eastward, at rates from 65 to 90 mm/yr. This forms an eastern flank of the spreading system behind the South Sandwich Arc.
There is some speculation that the westward motion of the South American Plate may have forced the Caribbean and Scotia Plates at its northern and southern ends respectively to squeeze around it. Both share a similar shape and are being subducted along their eastern boundary.
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