Antarctica’s Thwaites Glacier, aptly nicknamed the Doomsday Glacier, is a ticking time bomb. The rapidly melting body of ice could cause up to 10 feet (3 meters) of global sea-level rise if it were to collapse completely. New evidence suggests the glacier is even less stable than previously believed, with hundreds of iceberg earthquakes shaking up the massive structure for more than a decade.
Thanh-Son Pham, a researcher at the Australian National University, uncovered evidence of hundreds of glacial earthquakes that took place in Antarctica from 2010 to 2023. Most of those earthquakes have previously gone undetected due to their low-frequency seismic waves, and their discovery raises new questions about the threatening instability of Antarctica’s melting glaciers.
The new study, published in Geophysical Research Letters, reports 362 glacial earthquakes in Antarctica. Out of the newly documented seismic events, 245 earthquakes took place in Antarctica’s Doomsday Glacier, likely caused by capsizing icebergs.
Thin ice
Glacial earthquakes are a newly discovered type of seismic event that produces low-frequency waves, with a magnitude of around 5. They were first detected in 2003 and are mainly caused by the collapse of large icebergs.
Most of the recorded glacial earthquakes were discovered along the coast of Greenland, the largest ice cap in the Northern Hemisphere. Although scientists assumed that glacial earthquakes take place in Antarctica as well, they have been much harder to detect because they are of much lower magnitude than those that occur in Greenland.
Rather than relying on the global network of seismic detectors, Pham used seismic stations in Antarctica itself to find evidence for glacial earthquakes. The search turned up hundreds of events that were never cataloged.
The majority of glacial earthquakes took place near Antarctica’s largest glacier, Thwaites. Recent evidence has shown that the amount of ice flowing from Thwaites has doubled in the span of three decades, contributing to the global rise in sea levels.
The new study found that the rocking seismic events don’t necessarily coincide with the seasonal movement of warm air temperatures in Antarctica. Instead, the glacial earthquakes near Thwaites seem to take place in parallel with a period of accelerated flow of the glacier’s ice tongue toward the sea.
The remaining glacial earthquakes recently detected took place near the Pine Island Glacier, one of the largest ice streams in Antarctica. These events, however, took place around 30 to 50 miles (60 to 70 kilometers) away from the waterfront and are therefore not likely caused by capsizing icebergs. “The nature of earthquakes in Pine Island Glaciers remains puzzling and warrants further investigation,” the study notes.
Pham recommends follow-up investigations of the newly cataloged glacial earthquakes in Antarctica to better understand the main driving cause, as well as their impact on the instability of the glaciers.