On our planet everything is somehow connected and actions on one side can trigger reactions on a far away side of the earth. For example, our actions in the northern hemisphere affect the distant Antarctic and vice versa. At least this is how the results of a US-American research group can be summarized. The team came to this conclusion while studying seismic records at the world’s southernmost volcano, Mount Erebus.
Two earthquakes with magnitudes between 8.6 and 8.8 that struck Chile in February 2010 and Indonesia in April 2012 also caused Mount Erebus, a volcano thousands of miles away, to tremble, according to researchers. In the process, they triggered so-called ice quakes. These are vibrations in the glacier area surrounding the volcano. Normally, such quakes would be triggered by the activity of the volcano. “In a glaciated volcano with active eruptions, discriminating between icequakes, tectonic earthquakes and eruption events is crucial for understanding the origin of local seismicity,” writes the team led by Chenyu Li, a geophysicist and lead author of the study. According to the researchers, it turns out that similar icequakes had previously been observed only at high elevations of the volcano. The fact that strong earthquakes, which had taken place between 6,000 and 11,000 kilometres away, can trigger such icequakes at the volcano is quite a surprise for scientists.
For their study, the research team analyzed seismic activity between 2000 – 2017 at Mount Erebus, the southernmost active volcano in the world . In the process, Chenyu Li discovered microquakes at the volcano that were not related to eruption activities of the volcano. A closer examination showed that these microquakes had occurred one day before and after 43 more distant quakes, and seven of them had triggered seismic activity, i.e. icequakes, at the volcano. The triggering waves travel close to the surface and can thus trigger shallow icequakes in the volcano’s glacier belt. According to the team, such events are also dependent on the season and they conclude that teleseismic earthquakes could trigger activity at the volcano mainly in summer. However, more data would need to be collected to support this statement. In any case, the study, published in the journal Seismological Research Letters , shows that the 3,794-metre-high volcano is quite sensitive to tremors, even in distant parts of the world. However, it is not known whether they are strong enough to enhance volcanic activity, for example. The team’s findings are of interest to Scott Base and McMurdo Station, which are located in the vicinity of the volcano, in order to distinguish any activity patterns of the volcano. A network of permanent measuring stations around the very active stratovolcano registers the smallest seismic movements.
The quakes mentioned by researchers had struck Chile in February 2010 and Indonesia in April 2012. While the quake in Indonesia was not so severe in terms of destruction, tsunami and, most importantly, loss of life, it was a different story in Chile. This quake was considered the sixth most severe quake since global records began, and along with a triggered tsunami, over 500 people lost their lives. The shock waves of the quake were also felt in neighbouring Argentina. Now it turns out that this quake even had its effects almost 6,000 kilometres further south. The distance between the epicentre in Indonesia and Mount Erebus seems even more dramatic: a whopping 11,000 kilometres separate the two points. Antarctica itself is also a seismically very active region. In addition to the region around the volcano Mount Erebus, the Antarctic Peninsula is also highly active and only recently a severe earthquake had shaken the northern tip of the peninsula.
Dr Michael Wenger, PolarJournal
Link to the study: Chenyu Li, Zhigang Peng, Julien A. Chaput, Jacob I. Walter, Richard C. Aster; Remote Triggering of Icequakes at Mt. Erebus, Antarctica by Large Teleseismic Earthquakes. Seismological Research Letters 2021; doi: https://doi.org/10.1785/0220210027
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