earthquake a peak occurred around the Orca Seamount volcano resting 900 m above the seafloor in Bransfield Strait, a narrow passage between the South Shetland Islands and the north-western tip of Antarctica. In this area, the Phoenix tectonic plate is dipping beneath the Antarctic tectonic plate, creating a network of fault zones, stretching some parts of the crust and opening cracks in others. Study co-author Simone Cesca, a seismologist at the German Geosciences Research Center GFZ in Potsdam, said: “Similar volcanic eruptions have happened elsewhere on Earth, but this is the first time we’re seeing them in Antarctica.”
Scientists at research stations on King George Island, one of the South Shetland Islands, were the first to feel the shock from small earthquakes.
The researchers had to use Data from these seismic stations as well as data from two earth stations of the Global Navigation Satellite System to measure ground displacement. They also examined data from more distant seismic stations and from orbiting satellites that use radar to measure displacement near the ground.
By compiling this data, the team was able to create a picture of the underlying geology that caused this massive earthquake.
The two largest earthquakes in the series were the 5.9 magnitude earthquake in October 2020 and the 6.0 magnitude earthquake in November. After the November earthquake, seismic activity gradually subsided.
Research shows earthquakes on King George Island appear to have shifted by 11 centimeters. Only 4% of this shift can be directly explained by the earthquake. Scientists suspect that the movement of magma into the crust is largely responsible for the dramatic shifting of the ground.
If there had been an underwater eruption, it would likely have occurred at that time, the researchers added. But so far there is no direct evidence of an outbreak. To confirm that the giant volcano erupted, scientists must send a research team into the strait to measure the depth of the sea floor and compare it to historical maps.