Doomsday Glacier: Hundreds of iceberg quakes detected in Antarctica

A new study has uncovered evidence of more than 360 glacial earthquakes in Antarctica between 2010 and 2023, most of them occurring near the Thwaites Glacier, also known as the "Doomsday Glacier."

The findings, published in Geophysical Research Letters, highlight the growing seismic activity at the glacier’s marine end, suggesting a link between ice movements and potential rapid sea-level rise, according to LiveScidence. 

Glacial earthquakes occur when massive chunks of ice, known as icebergs, break off from glaciers and fall into the ocean. The resulting violent collision between the icebergs and the "mother" glacier generates strong seismic waves that can travel thousands of kilometers. These quakes, however, are distinct from typical earthquakes: they don't produce high-frequency seismic waves, making them difficult to detect using standard seismic monitoring equipment. As a result, it wasn't until relatively recently that glacial earthquakes were discovered, despite similar seismic sources being recorded for decades.

Historically, these events have been most frequently observed in Greenland, where the quakes are relatively large and detectable by a global network of seismic stations. These Greenland quakes also show seasonal patterns, with more frequent occurrences during the late summer months. The rising frequency of these events in recent decades is thought to correlate with faster global warming in polar regions.

In contrast, Antarctica, the largest ice sheet on Earth, had seen fewer documented glacial earthquakes until now. Most prior attempts to detect these quakes relied on the global seismic network, but due to the lower magnitude of Antarctic glacial earthquakes, many went unnoticed. The new study, led by a team of researchers, focused on using seismic stations within Antarctica itself, uncovering over 360 events. The majority of these events occurred near the Thwaites and Pine Island glaciers, both of which have been major contributors to sea-level rise.

A striking 245 of the detected events were concentrated around the marine end of Thwaites Glacier. These events are believed to have been triggered by the capsizing of icebergs, a common cause of glacial earthquakes.

Unlike the seasonal patterns seen in Greenland, the most active period for these quakes in Antarctica occurred between 2018 and 2020, a time when the glacier's ice tongue—an extension of ice flowing into the ocean—accelerated towards the sea. This speed-up was independently confirmed by satellite observations, suggesting that changes in ocean conditions may be influencing the glacier's movement.

The rapid movement of the Thwaites Glacier is of particular concern to scientists, as its collapse could lead to a dramatic rise in global sea levels. If Thwaites were to collapse entirely, it could raise sea levels by up to 3 meters, a scenario that would have catastrophic effects on coastlines worldwide. The new study sheds light on the glacier's instability, offering valuable data that could help predict future sea-level rise.

While the Thwaites Glacier is currently the focus of much attention, the study also revealed seismic activity near the Pine Island Glacier. However, these events were located further inland, away from the glacier's marine terminus, suggesting they were not caused by iceberg calving. The cause of these seismic events remains uncertain, and further research is needed to understand their significance.

By Sabina Mammadli