Where it is and what it carries
The Shetland Plate is one of the smallest plates in the PB2002 model, about 72,000 km². It carries the South Shetland Islands, a chain of volcanic and ice-covered islands north of the Antarctic Peninsula, including King George Island, Livingston Island, Deception Island and Penguin Island. King George Island hosts several national research stations. In the dataset the plate holds almost none of Antarctica’s land area, because the islands are small next to the continent.
The islands are an old volcanic arc built over a subduction zone. The crust mixes arc rocks and older continental basement, with oceanic crust on the seafloor around them.
What happens at its edges
Almost all of the plate’s boundary is with the Antarctic Plate, about 1,020 km in total, and PB2002 gives it a relative speed of about 1.0 cm/yr. This single boundary has two very different parts. To the north lies the South Shetland Trench, where former Phoenix Plate seafloor, now counted as part of the Antarctic Plate, sank beneath the islands. To the south lies the Bransfield Strait, a young rift where the crust is pulling apart and the islands are separating from the peninsula.
In the east, a short boundary of about 210 km meets the Scotia Plate, converging at about 0.9 cm/yr.
Why geologists treat it as separate
The Phoenix Plate once subducted along this margin. When spreading on its ridge stopped, the leftover slab kept sinking and rolling back, which most researchers think opened the Bransfield Strait behind the arc. That motion cuts the islands off from the peninsula as a separate block. The plate’s motion is slow and its exact edges are uncertain, so it is one of the more debated microplates in PB2002.
Earthquakes and volcanoes
The dataset lists 2 earthquakes of magnitude 6.5 or larger since 1900, a M6.6 in 2012 and a M6.5 in 2026, both in the South Shetland Islands. In 2020 and 2021 an intense earthquake swarm near a submarine volcano in the Bransfield Strait drew scientific attention to the active rifting there.
The plate has 4 volcanoes in the dataset. Deception Island is the most active and best known, with eruptions between 1967 and 1970. Penguin Island, a small cone off King George Island, is another young volcano.