In this article, researchers discuss how large tsunamis may become more common due to climate change. Dixon Fjord in August 2023: Just weeks after this photo was taken, a large section of the mountain slid into the sea, triggering a huge wave that reverberated through the fjord 10,000 times over nine days and shook the entire land. Seismologists at the Witter Boon/Flanders Marine Institute have detected an unusual signal at monitoring stations used to detect seismic activity in September 2023, including ours. We've seen this signal on sensors everywhere, from the Arctic to Antarctica. We were intrigued – the signal was unlike any we had recorded before. Instead of the frequency-rich “rumble” of an earthquake, it was a dull hum, with only one vibrational frequency. Even more surprising was that the signal continued for nine days. Initially classified as an “Unidentified Seismic Object” (USO), the signal's origin was eventually attributed to a massive landslide in the remote Dickson Fjord in Greenland. A staggering volume of rock and ice, enough to fill 10,000 Olympic-sized swimming pools, plunged into the fjord, triggering a 200-meter-high megatsunami and a phenomenon known as a seche: a wave in an ice fjord that retreats and advances. , about 10 thousand times in nine days. In the context of tsunamis, this 200 meter wave was twice the height of London's Big Ben tower and many times larger than anything recorded after the massive earthquakes in Indonesia in 2004 (the Boxing Tsunami) and Japan in 2011. (the tsunami that hit the Fukushima Nuclear Power Plant). It was probably the strongest wave anywhere on Earth since the 1980s. Our findings, now published in the journal Science, were supported by 66 scientists from 40 institutions in 15 countries. As with plane crash investigations, solving this mystery requires collecting a variety of evidence, from enormous amounts of seismic data to satellite images, water level monitoring in fjords and detailed simulations of the evolution of tsunami waves. . All of this highlighted a catastrophic and cascading chain of events, from decades to seconds of collapse. The slide descends a very steep glacier into a narrow gorge before plunging into a narrow, enclosed fjord. Eventually, decades of global warming thinned the glacier by several tens of meters, meaning the mountain it once climbed could no longer hold. The climate change tsunami caused uncharted waters to shake the Earth for nine days a year ago. But beyond the strangeness of this scientific marvel, the event highlights a deeper, more disturbing truth: climate change is reshaping our planet and our scientific methods in ways that we have. we are just beginning to understand. It is a stark reminder that we are navigating uncharted waters. Just a year ago, the idea that a tsunami could last nine days was considered absurd. Similarly, a century ago, the idea that global warming could destabilize Arctic slopes, causing large-scale landslides and tsunamis almost every year, would have been considered absurd. However, these once unimaginable events are now becoming our new reality. As we move into this new era, we can expect to witness more events that challenge our previous understanding, as our experience does not include the extremes we face now. We saw a nine-day wave that no one could have imagined before. Traditionally, discussions about climate change have focused on observing the atmosphere and oceans, weather patterns and sea level rise. But Dixon Fjord forces us to look at the crust beneath our feet. Perhaps for the first time, climate change has caused a seismic event with global implications. The Greenland landslide sent tremors through the Earth, shaking the planet and creating seismic waves that traveled around the world within an hour of the event. No part of the ground beneath our feet is immune to these vibrations, opening – metaphorically – cracks in our understanding of these phenomena. The rare tsunami that hit Brazil in 1755 will happen again, although landslides and tsunamis have been recorded before, the first in September 2023 in East Greenland, an area that seemed immune to such catastrophic events induced due to climate change. And it certainly won't be the last landslide megatsunami. As permafrost (permanently frozen ground) on steep slopes continues to warm and glaciers melt, we can expect these events to occur more frequently and on a larger scale in the world's polar and mountainous regions. The recently identified unstable slopes in West Greenland and Alaska are clear examples of impending disaster. As we face these extreme and unpredictable events, it becomes clear that our existing scientific methods and tools must be completely reformed to deal with them. We didn't have a standard workflow for analyzing the 2023 event in Greenland. We also need to adopt a new mindset, as our current perception is shaped by an almost extinct and previously stable climate. As we continue to alter our planet's climate, we must prepare for unexpected events that challenge our current understanding and require new ways of thinking. The ground beneath us is shaking literally and figuratively. While the scientific community must adapt and pave the way for informed decisions, it is up to decision makers to act. *Stephen Hicks is a research associate in computational seismology at UCL. *Kristian Svenvig is a senior researcher at the Department of Mapping and Mineral Resources, Geological Survey Denmark and Greenland. **This article was originally published on The Conversation Brasil website. Lisbon, with more than 3 thousand years of history, was rebuilt after the 1755 earthquake, but there are still ruins.
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