The Invisible Force: Greenland Tsunami Wave Causes Global Vibration

TEMPO.CO, Jakarta - In September 2023, the world's seismographs and researchers were shocked by a vibration that came out of nowhere. When the signal was detected worldwide, seismologists couldn't figure out what it was. Carl Ebeling, a seismologist at the Scripps Institution of Oceanography, University of California, San Diego, said, “This very, very weird signal showed up that I’d never seen before at some of our stations in the North.” 

Today, the case has been solved with the participation of 68 researchers from 40 institutions in 15 countries for a year of research. At first, they couldn't even call it an earthquake because it was such a strange event. Research leader Dr. Kristian Svennevig of the Geological Survey of Denmark and Greenland explained:

"At the beginning of this scientific investigation, everyone was confused and had no clue about the source of this signal. It was unusually prolonged and straightforward compared to typical earthquake signals, which usually last for minutes or hours, and was initially classified as a USO - an unidentified seismic object".

After integrating seismic data, field measurements, both ground-based and satellite imagery, and high-resolution computer simulations of tsunami waves, the case is finally cracked. On September 16, 2023, a 1,200-meter-high mountain peak collapsed into the remote Dickson Fjord after the melting glacier beneath it could no longer support the rock face. The tsunami waves, some reaching heights comparable to the Statue of Liberty, crashed over the steep cliffs that line the fjord. 

Because the landslide hit the waterway at an angle of nearly 90 degrees, the waves bounced back and forth across the fjord for nine days - a phenomenon known as a seiche. The initial collapse created a massive wave that rose to 200 meters. After that, the continuous movement of water in the twisting fjord created seismic waves that traveled through the earth.

It was also discovered that immediately after the tremors, a major landmark on the remote island of Ella (45 miles from the landslide) was destroyed, as reported by a cruise ship traveling near the fjords in Greenland. The landslide and mega-tsunami were the first to be detected in eastern Greenland. Arctic regions are experiencing the fastest rates of global warming, and similar events, although less seismically intense, have been observed in western Greenland, Alaska, Canada, Norway, and Chile.

The analysis, published in the journal Science, estimates that 25 million cubic meters of rock and ice fell into the fjord and traveled at least 2,200 meters along its length. The direction of the landslide, which was perpendicular to the length of the fjord, combined with the fjord's steep, parallel walls and a 90-degree bend 10 kilometers downstream, contributed to retaining much of the landslide's energy within the fjord and prolonging its resonance.

At last, the researchers concluded that the event was primarily caused by global warming, which has had a significant impact worldwide. They noted that as temperatures rise rapidly, large landslides can occur in previously stable areas. As global temperatures continue to rise, such events are expected to become more common.

"Even more profoundly, for the first time we can clearly see that this climate-change-induced event caused a global vibration under all our feet, all over the world," Mangeney said. “Those vibrations traveled from Greenland to Antarctica in less than an hour. So we’ve seen an impact from climate change impacting the entire world within just an hour.” 

The Guardian | NBC News

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