Antarctica’s most dangerous glacier is coming apart, and scientists just discovered we’ve been missing the warning signs. Researchers have detected 368 previously unknown earthquakes shaking Thwaites Glacier between 2010 and 2023, revealing a pattern of accelerating destruction that nobody saw coming.
These aren’t ordinary earthquakes. Each seismic event marks the violent capsize of massive icebergs as they break away from the glacier’s edge and flip over in the ocean. The discovery represents a fundamental shift in our understanding of how Antarctica’s ice is collapsing into the sea.
Thwaites Glacier in West Antarctica has earned its nickname as the Doomsday Glacier for good reason. This single mass of ice holds enough water to raise global sea levels by 65 centimeters, more than two feet. If it collapses entirely, coastal cities from New York to Shanghai face catastrophic flooding. The glacier is already in crisis mode. Thwaites is currently responsible for roughly 4% of all global sea level rise, and that contribution is accelerating each year. The glacier discharges ice into the ocean faster than any other glacier in Antarctica, and recent studies have shown warm ocean water is melting the ice shelf from below through underwater vortex systems. Now scientists have discovered a second, simultaneous crisis: the glacier is literally shaking itself apart from within.
Dr. Thanh-Son Pham from the Australian National University developed a detection system that could find seismic events other monitoring networks missed entirely. The breakthrough came from focusing on a specific type of seismic wave that travels relatively short distances before fading away. Traditional earthquake monitoring systems watch for long-period seismic waves that can travel thousands of kilometers around the planet. These global networks successfully detected glacial earthquakes in Greenland for years. But in Antarctica, most glacial earthquakes generate shorter-period waves between 17 and 25 seconds that dissipate before reaching distant sensors.
By placing seismic monitoring stations on land within 1,100 kilometers of the glacier and tuning the detection algorithm to these shorter waves, researchers could finally see what was happening. The results shocked the scientific community. The automated detection system identified 2,461 potential seismic events. After filtering out offshore tectonic earthquakes and manually inspecting the remaining signals, researchers confirmed 368 genuine glacial earthquakes. Most had never been recorded in any catalog before. These events ranged from magnitude 2 to 3, powerful enough to send measurable vibrations through the Antarctic ice sheet.
The process generating these earthquakes is both simple and terrifying. As the glacier flows toward the ocean, it reaches the terminus where ice meets water. Here, massive chunks break off in a process called calving. When these newly formed icebergs are taller than they are wide, they become unstable. The iceberg begins to capsize, rotating in the water like a falling tree. But this isn’t a quick flip. The rotation takes roughly 15 seconds for the smaller events detected in this study, much faster than the 50-second capsizes that generate the largest glacial earthquakes observed in Greenland.
As the iceberg rotates, it pushes against the glacier behind it with enormous force. This horizontal force transfers into the solid Earth, creating seismic waves that radiate outward through the bedrock and ice. Seismic stations hundreds of kilometers away record the distinctive signal of surface waves generated by the capsizing event. Researchers could even determine the direction of force by analyzing the seismic waves. In almost every case, the force aligned with the glacier’s flow direction, exactly what you’d expect from an iceberg pushing backward against the glacier as it tips over.
The true alarm came when researchers analyzed when these earthquakes occurred. The detection rate wasn’t constant. Between 2018 and 2020, glacial earthquakes at Thwaites surged to unprecedented levels, far exceeding the rate in earlier or later years. This spike couldn’t be explained by changes in monitoring capability. The number of seismic stations in the region was actually highest in 2016, yet the earthquake count peaked in 2018. Something fundamental changed in the glacier’s behavior during that three-year window.
Satellite observations of ice movement provided the missing piece of the puzzle. During the same 2018 to 2020 period when earthquakes spiked, the central ice tongue of Thwaites Glacier suddenly accelerated. The floating extension of the glacier began moving 20 to 40 percent faster than in adjacent time periods. While the main body of the glacier on land showed no significant change in speed, the ice tongue rushing toward the ocean experienced dramatic acceleration.
The connection between ice speed and earthquake frequency reveals a dangerous feedback loop. Thwaites Glacier’s terminus consists of three distinct segments. An elongated island to the north creates a stable eastern ice shelf where the ice remains relatively protected. The western calving front faces open ocean where icebergs can drift freely away. The central ice tongue, where most earthquakes occur, contains a chaotic jumble of conglomerated icebergs of various sizes locked together by fast sea ice.
Under normal conditions, this fast sea ice between icebergs acts like glue, creating back pressure that slows the glacier’s advance and prevents newly formed icebergs from capsizing. When the ice tongue accelerated during 2018 to 2020, that protective fast ice weakened and began breaking apart. With less resistance, the glacier fragmented more rapidly into smaller icebergs. These smaller pieces became more prone to capsizing because their proportions made them top-heavy and unstable.
Each capsizing event detected by seismometers represented not just a single iceberg flipping over, but evidence of a glacier losing its structural integrity. The acceleration that triggered this cascade of failures came from ocean forces that scientists still don’t fully understand. External forcing from changing ocean conditions drove the ice tongue to speed up, which weakened the ice mélange, which increased fragmentation, which generated more unstable icebergs, which created more earthquakes. The process feeds on itself.
The Thwaites events weren’t the only glacial earthquakes detected in the study. Pine Island Glacier, the second-largest contributor to sea level rise in Antarctica, also registered significant seismic activity. But these events present a mystery. Unlike the Thwaites earthquakes located near the glacier terminus where icebergs calve, the Pine Island events clustered near the grounding line, the point where the glacier lifts off the bedrock and begins floating. This location sits several tens of kilometers inland from where icebergs would normally break off and capsize.
The physical mechanism generating earthquakes so far from the calving front remains unknown. Systematic mislocation of these events seems unlikely because they were detected using the same methods and station configurations that successfully located the Thwaites earthquakes. Another research team using completely different detection methods based on higher-frequency seismic waves found events in the same Pine Island location, confirming the signals are real. The glacier appears to be generating seismic activity through some process other than iceberg capsizing, but what that process might be remains an open question demanding further investigation.
The discovery of 368 previously unknown glacial earthquakes in Antarctica carries implications far beyond academic interest in seismic monitoring techniques. Every earthquake represents ice being discharged from the continent into the ocean. Every capsizing iceberg means the glacier moved one step closer to catastrophic collapse. The accelerating earthquake rate during 2018 to 2020 provided direct evidence that Thwaites Glacier can suddenly shift into a more destructive mode of behavior.
The seismic monitoring network that detected these events only covered West Antarctica, and only during specific time periods when temporary research stations operated. Vast sections of the Antarctic coastline remain unmonitored. If Thwaites Glacier alone generated 368 detectable earthquakes in thirteen years, how many glacial earthquakes are occurring across the entire continent that nobody is measuring? The true scope of Antarctic ice discharge through this mechanism remains completely unknown.
The shorter-period nature of Antarctic glacial earthquakes compared to their Greenland counterparts suggests fundamental differences in how the two ice sheets are failing. Greenland’s largest glacial earthquakes generate such powerful long-period waves that seismometers on the opposite side of the planet can detect them. Antarctic events produce shorter, faster seismic signals that fade within regional distances. This difference may reflect variations in iceberg size, water depth, or the mechanical properties of the ice itself. Understanding why Antarctic and Greenland glaciers generate different seismic signatures could reveal important information about what controls the rate of ice discharge.
Machine learning tools trained on this new dataset of confirmed glacial earthquakes could potentially scan through decades of archived seismic data to find events that were missed by traditional detection methods. Similar approaches applied to Greenland seismic data have successfully identified glacial earthquakes that global monitoring networks overlooked. A comprehensive reanalysis of Antarctic seismic records might reveal centuries of glacial earthquake activity, providing a longer baseline to assess whether current rates of activity are truly unusual or part of natural variability.
The correlation between ice tongue acceleration and earthquake frequency demonstrates that changes in ocean conditions can rapidly destabilize glaciers in ways that seismic monitoring can track in real time. As ocean temperatures continue rising and circulation patterns shift, similar acceleration events may become more common. Maintaining and expanding the seismic monitoring network in Antarctica could provide early warning of glaciers transitioning into more active states of collapse.
Thwaites Glacier faces a double threat. Warm ocean water attacking from below through underwater vortex systems melts the ice shelf, thinning it and reducing its ability to buttress the glacier behind it. Simultaneously, the structural failure processes generating these glacial earthquakes tear the glacier apart from the calving front. Two independent destruction mechanisms working in concert to dismantle the most dangerous glacier on Earth. The seismic record shows this isn’t a slow, steady process but one marked by sudden accelerations that scientists cannot yet predict or fully explain. The Doomsday Glacier is shaking, and the tremors are getting stronger.
Source:
Researchers systematically detected 368 previously uncatalogued glacial earthquakes at Thwaites Glacier in West Antarctica between 2010 and 2023, revealing an alarming spike in seismic activity between 2018 and 2020 that correlates with episodic speed-ups of the glacier’s ice tongue (Pham, 2025, https://doi.org/10.22541/essoar.175596888.87914182/v1
