Undersea volcano wakes up causing 85,000 earthquakes

Orca Seamount volcano graphic at the bottom of Bransfield Strait – Photo: WIKIPEDIA

The earthquake started in August 2020 and has lasted until now.

According to the news site Live Scienceearthquakes occurred around Orca Seamount, a volcano 900m high at the bottom of Bransfield Strait, a narrow passage between the South Shetland Islands (Antarctica) and the northwestern tip of Antarctica. This volcano has been inactive for a long time.

In this region, the Phoenix tectonic plate is diving beneath the Antarctic continental plate, creating a network of fault zones of the Earth’s crust, according to a study in the journal Polar Science.

Study co-author Simone Cesca, a seismologist at the GFZ German Center for Geosciences in Potsdam (Germany), told Live Science: “There have been similar earthquakes elsewhere on Earth, but this is the first time we have observed earthquakes around the Orca Seamount volcano.”

Scientists at research stations on King George Island, one of the South Shetland Islands, were the first to feel the sound of small earthquakes. They quickly connected with seismologist Cesca and colleagues around the world.

“The team wanted to understand what was going on, but King George Island was far away, with only two seismic stations nearby,” Cesca said. So the researchers used data from these seismic stations, as well as from two global satellite navigation system ground stations, to measure ground displacement.

They also looked at data from more distant seismic stations and Earth-orbiting satellites that use radar to measure displacement at ground level.

According to a scientific article published in the journal Communications Earth & Environmentby stitching these data together, the team was able to create a picture of the underlying geology that caused this massive earthquake.

The two largest 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 waned.

The study also showed that earthquakes appear to have moved the ground on King George Island by about 11cm.

Scientist Cesca confirmed that the Orca Seamount giant volcano blew off its top. He said scientists will have to make a trip to Bransfield Strait to measure the depth of the sea floor and compare it with historical maps.