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Researchers at Penn State University have found that earthquakes in a major ice stream in West Antarctica are driven by ocean tides. Thoroughly understanding the phenomenon will help researchers understand the melting of the continent.
Ice streams or glaciers flow at high speed and act as a drainage sys Phone Number List tem that carries frozen masses from the land to the ocean . The research group's findings published in the Journal of Geophysical Research: Earth Surface explain that earthquakes in the Antarctic zone are more frequent during the spring currents that follow the full moon and have a greater range of tidal heights.
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In five years, seismic monitors recorded more than 2,200 ice earthquakes in five years on the Bahía Buen Suceso glacier ( Foundation Ice Stream , in English) located in West Antarctica. Erica Lucas, a geoscience researcher at Penn State, details that “the tides are driven by the orbits of the Moon and the planet, and it is fascinating to be able to establish a connection between the tides and ice processes on Earth.”
The scientists' observations determined a distinct seasonal change in the time of day that icequakes occurred attributable to the daily high tide recorded throughout each year. According to the research, the seismic events in Foundation Ice Stream occurred around the grounding line caused by tension built up between the ice and bedrock.
In the area where ice sheets break off from rocks to float in the ocean, frozen water platforms act as a foothold that prevents the passage of land ice into the ocean. When the tide rises, the ice is pushed up causing a buildup of tension which then slides. The process is known as “ stick-slip” .
Ice earthquakes and melting in Antarctica
The scientists reached these conclusions after analyzing a long-term data set collected by the Polar Earth Observation Network (POLENET), a system of seismic stations installed throughout Antarctica. The analysis only focused on a single ice stream. Andrew Nyblade, professor of geosciences and co-author of the study, says the research “points to the growing importance of ice earthquakes for investigating grounding line processes and understanding glacier dynamics.”
Luca assures that "if we can better understand the physical processes of ice flow, then that will be another piece of the puzzle to understand the loss of ice mass from Antarctica."
At least 2.6 million square kilometers of sea ice have disappeared in Antarctica in the last 13 years. There are no signs of that area being replenished. The data revealed by the latest report from the United States National Snow and Ice Data Center (NSIDC) confirm that there is a deficit of frozen sea surface of a size similar to the territory of Argentina .
The research team points out that it will be necessary to place seismometers directly at the site to collect more precise data to establish a more certain relationship between marine currents, ice earthquakes and the melting of Antarctic ice.
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發表於 2024-3-12 13:11:26