Shallow M7.1 earthquake hits South Shetland Islands, Antarctica

An intense earthquake swarm continues in Bransfield Strait, Antarctica, with a very strong and shallow earthquake registered by CSN Chile and EMSC as M7.1 at 23:36 UTC on January 23, 2021. USGS is reporting it as M6.9 at a depth of 9.6 km (6 miles).

The epicenter was located near the southern coast of Elephant Island and east of King George Island.

According to the National Seismological Center at the University of Chile, more than 30 000 earthquakes have been registered in the Bransfield Strait, a 96 km (60 miles) ocean channel between the South Shetland Islands and the Antarctic Peninsula, from August to December 2020.

Yesterday's M7.1/M6.9 is the strongest in the sequence.

Several tectonic plates and microplates meet in this area, leading to frequent rumbling, but the past months have been unusual.

Most of the seismicity was concentrated at the beginning of the sequence, mainly during the month of September, with more than a thousand earthquakes a day, the center said.

Image credit: Berricoso et al. (2008)

Due to these frequent earthquakes, the strait is now expanding from the Antarctic Peninsula about 15 cm (6 inches) per year, nearly 20 times faster than before (7 to 8 mm (0.30 inches) per year).

Reference:

Reporte Sismicidad Estrecho de Bransfield – Reporte para Onemi – November 21, 2020 (source)

Featured image credit: TW/SAM, Google