In September 2023, an unusual vibration was measured at a series of seismic stations around the world. The shaking was not caused by an earthquake, but it lasted a long time – nine days. It occurred to many scientists that the instruments might have broken. An international investigation lasting almost a year found out what happened and why. sciences She posted the solution in her columns.
Long-term seismic signals were detected from Germany to Alaska, and a team of 69 scientists from 17 countries analyzed measurements and satellite images and finally found the source of the anomaly on the desolate east coast of Greenland, where at the same time a larger piece of rocky coastline had been lost.
The earth-shattering event was a landslide triggered by a melting glacier in Greenland’s Dixon Strait. The 1,200-meter-high mountainside at the end of the glacier collapsed on September 16. The massive fall of rocks and ice into the 540-meter-deep waters created waves more than 200 meters high, which bounced back and forth between the shores of the 10-kilometer-long bay and turned into standing waves that rocked the entire strait.
This shuttle, called the lake, traveled back and forth along the fjord every 90 minutes. Although this movement of water had been known for a long time, researchers had not thought it could last for days.
What does the water hide?
Analyzing the seismic signal can help us understand the underlying processes and lead to more effective monitoring in the future. If we don’t study it from a seismic perspective, we may not even know that something is shaking the waters of the fjord system.
– Angela Carrillo Pons, an employee at the German Research Center for Geosciences (GFZ), pointed out.
Long-lasting tremors caused by avalanches in glaciers have been observed before, but the September case was much longer. Carrillo-Pons said they were able to estimate the amount of energy released, but it was not possible to clearly determine the cause of the landslide until then.
Scenarios
Around the Arctic, and with it Greenland, temperatures are rising four times faster than the global average, with specific life-threatening consequences. Greenland’s coasts and mountains are becoming increasingly unstable due to melting ice. Large and small landslides are not uncommon. In 2017, a tsunami swept away four people and their homes in the village of Nuugaatsiaq, near Karatfjord in western Greenland. At other times, tsunami waves higher than 100 metres have been observed on European coasts thousands of kilometres away.
According to experts, it is logical to assume that we will encounter events similar to those now discovered more often in the near future. Just because there are areas full of such fjords not only in Greenland, but also in Alaska, Canada and Norway.
As for the mega-tsunami in the Dickson Strait, no one was hurt. The waters washed away two historical monuments and an uninhabited military facility. At the same time, there is also a relatively busy cruise route here – fortunately, there was no boat here at the time of the incident that could face the hundred-meter waves.
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