Antarctica’s doomsday glacier shaken by hundreds of iceberg earthquakes
Flipping icebergs collide violently with the collapsing tip of Doomsday Glacier
Thwaites Glacier in West Antarctica is visible in this image taken by the Copernicus Sentinel-1 mission on March 2, 2024. More and more ice keeps breaking from the unstable glacier and falling into the sea.
©ESA/Copernicus Sentinel-1
The following essay is republished with permission 
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Glacial earthquakes are a special type of earthquake that occur in cold, icy regions. First discovered in the Northern Hemisphere more than 20 years agoThese earthquakes occur when large chunks of ice from glaciers fall into the sea.
So far, very few have been found in the Antarctic. in a new Study Published in Geophysical Research Letters, I present evidence from hundreds of such earthquakes in Antarctica between 2010 and 2023, most of which were at the seaward end of Thwaites Glacier – the so-called doomsday glacier that could rapidly raise sea levels if it collapsed.
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a recent discovery
Glacial earthquakes occur when long, thin icebergs fall from the end of a glacier into the ocean.
when this iceberg capsize the boatThey collide violently with the “mother” glacier. The collision produces strong mechanical ground vibrations, or seismic waves, that extend thousands of kilometers from the original location.
What makes glacial earthquakes unique is that they do not produce any high-frequency seismic waves. These waves play an important role in detecting and locating specific seismic sources such as earthquakes, volcanoes, and nuclear explosions.
Because of this difference, glacial earthquakes were discovered relatively recently, despite other seismic sources. regularly documented For many decades.
varies with the seasons
Most of the glacial earthquakes ever found are located near End of glaciers in GreenlandThe largest ice cap in the Northern Hemisphere.
Greenland’s glacial earthquakes are of relatively large magnitude. The largest are similar in size to their cause nuclear test Held by North Korea over the past two decades. As such, they have been detected by high-quality, continuously operating seismic monitoring networks around the world.
greenland events varies with the seasonsOccurs more frequently in late summer. they also have become more normal in recent decades. These signals may be linked to faster rates of global warming in the polar regions.
elusive evidence
Although Antarctica is home to the largest ice sheet on Earth, direct evidence of glacial earthquakes caused by the overturning of icebergs there has been elusive. Most previous efforts to detect Antarctic glacier earthquakes used worldwide networks of seismic detectors.
However, if Antarctic glacial earthquakes are of much lower intensity than those in Greenland, the global network may not detect them.
In my new study, I used seismic stations in Antarctica itself to look for signals from these earthquakes. My search turned up over 360 glacier seismic events, most of which are not yet included in any earthquake catalog.
The occurrences I discovered were in two groups, near Thwaites and Pine Island glaciers. These are glaciers biggest sources Sea level rise from Antarctica.
Earthquake on Doomsday Glacier
Thwaites Glacier is sometimes also known as doomsday glacierIf it collapses completely, it will raise global sea levels by 3 meters and is likely to collapse rapidly,
Nearly two-thirds of the incidents I detected – 245 out of 362 – were located near the sea end of Thwaites. Most of these events are probable glacial earthquakes caused by the overturning of ice caps.
The strongest driver of such events does not appear to be the annual fluctuations of warm air temperatures that drive them. seasonal behavior Greenland glacier earthquake.
Instead, the most abundant period of glacial earthquakes at Thwaites, between 2018 and 2020, coincides with a period of accelerated flow of the glacier’s ice tongue toward the sea. The ice-tongue movement-period was independently confirmed. satellite Overview.
This motion may be due to oceanic conditions, the effects of which are not yet well understood.
The findings suggest effects of ocean states on the stability of marine-terminating glaciers on short-term scales. It is worth further exploration to assess the potential. Contribution Future sea level rise from glaciers.
The second largest group of discoveries occurred near Pine Island Glacier. However, these were consistently located 60–80 kilometers from the coast, so are unlikely to be caused by overturned icebergs.
These phenomena remain mysterious and require follow-up research.
What’s next for Antarctic glacial earthquake research?
Detecting glacial earthquakes associated with the movement of icebergs at Thwaites Glacier can help answer many important research questions. These include a fundamental question about potential instability Thwaites Glacier is formed by the interaction of sea, ice and solid land where it meets the sea.
Better understanding could be the key to solving the current big problem uncertainty Projected sea level rise over the next few centuries.
This article was originally published on Conversationread the original article,
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