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Deep in West Antarctica, far from human settlements, a dramatic and largely invisible process is unfolding. Scientists have detected hundreds of unusual earthquakes near the collapsing edge of the Thwaites Glacier — ominously nicknamed the Doomsday Glacier. These seismic events are not caused by shifting tectonic plates, but by massive icebergs breaking off, tipping over, and crashing into the ocean. The discovery is offering new insight into how Antarctica is losing ice and what that could mean for global sea levels.
Unlike conventional earthquakes, these “glacial earthquakes” are generated by ice movement. When a huge iceberg calves from a glacier and capsizes in seawater, it displaces an enormous volume of water. This motion sends low-frequency seismic waves through the Earth, which can be picked up by sensitive instruments. Because these signals are subtle and slow, they often go unnoticed unless researchers know exactly what to look for.
By analysing more than a decade of seismic records, scientists identified over 360 such iceberg-related earthquakes across Antarctica. A striking majority of them were concentrated around Thwaites Glacier, one of the most unstable and rapidly changing ice masses on the continent. These points point to intense and ongoing activity at the glacier’s seaward edge, where ice meets the ocean.
Why Thwaites Glacier Is So Critical
Thwaites Glacier holds a special place in climate science because of its sheer size and strategic position. Roughly the size of Great Britain, it drains a vast portion of the West Antarctic Ice Sheet. Much of its base lies below sea level and slopes downward inland — a configuration that makes it particularly vulnerable to warm ocean water.
As relatively warmer seawater flows beneath the glacier, it melts the ice from below, thinning it and weakening its grip on the bedrock. This process accelerates the glacier’s movement toward the ocean, increasing iceberg calving. Scientists fear that once this retreat crosses a certain threshold, it could become unstoppable.
If Thwaites were to collapse entirely, global sea levels could rise by about three metres. Even more concerning is its role as a buttress. The glacier currently helps hold back neighbouring ice systems; its failure could trigger a chain reaction, leading to far greater ice loss across West Antarctica.
What the Earthquakes Reveal
The newly detected earthquakes provide a rare window into processes that satellites alone cannot fully capture. While satellite images can show surface changes and ice speed, they cannot “hear” what is happening when icebergs detach, roll, and collide with the ocean. Seismic data fills this gap.
Interestingly, the glacial earthquakes near Thwaites do not follow a clear seasonal pattern. In Greenland, iceberg calving usually peaks during warmer months. At Thwaites, however, earthquake activity surged during certain years regardless of season. This suggests that factors such as ocean currents and subsurface melting play a bigger role than air temperature alone.
Researchers also observed that a spike in earthquake activity coincided with periods when the glacier’s ice tongue — a floating extension of the glacier — sped up significantly. This link strengthens the case that seismic monitoring can act as an early warning system for structural changes within glaciers.
Beyond Thwaites: A Broader Puzzle
While Thwaites was the main hotspot, scientists also detected a smaller cluster of unusual seismic events near Pine Island Glacier, another rapidly retreating glacier in West Antarctica. These events occurred farther inland and are not yet fully understood. They could be linked to ice fracturing, basal sliding, or other hidden processes beneath the ice sheet.
These findings highlight how little is still known about the inner workings of polar ice systems. Antarctica may appear silent and frozen, but beneath its surface lies a dynamic and increasingly unstable environment.
Why This Matters for the World
Sea-level rise is one of the most serious long-term consequences of climate change. Hundreds of millions of people live in low-lying coastal areas, and even small increases in sea level can worsen flooding, erode shorelines, and contaminate freshwater supplies.
Accurate predictions of future sea-level rise depend on understanding how fast major glaciers like Thwaites will lose ice. The discovery of iceberg-triggered earthquakes adds a powerful new tool to scientists’ toolkit, allowing them to track glacier behaviour in real time and refine climate models.
The detection of these hidden earthquakes underscores a crucial message: Earth’s ice sheets are not passive victims of warming, but active systems responding in complex ways to a changing climate. By “listening” to the seismic signals produced by breaking ice, scientists are gaining clearer insight into how close some glaciers may be to critical tipping points.
References:
https://espis.boem.gov/final%20reports/5196.pdf
https://tc.copernicus.org/articles/19/303/2025
https://www.sciencedirect.com/science/article/pii/S2590332220305923
Banner Image: Photo on Freepik by jannoon028 https://www.freepik.com/free-photo/icebergs-glacier-lagoon-iceland_1254098.htm#fromView=search&page=1&position=7&uuid=5dd1aef9-5490-4d6e-8ace-8714e486114b&query=glacier+antartica
