Global Shockwave: 650-Foot Tsunami Triggered Tremors Felt for 9 Days Straight
Global Seismic Event
On September 16, 2023, scientists picked up strange seismic waves reverberating from all over the world, for almost nine days. Experts were so fascinated by the phenomenon, that they identified the whole event as a USO (unidentified seismic object), Popular Mechanics reported. A thorough investigation was conducted by a team of scientists across 18 countries, and it was found that a rockslide in Dickson Fjord, located on the central east coast of Greenland was responsible for the massive seismic event. In a new study, published in the journal Science, researchers explain how a rockslide in Greenland managed to 'shake up' the world for so many days.
Not an Earthquake
In September 2023, scientists first encountered what would go on to become a 9-day-long, global 10.88-millihertz (92-second) monochromatic very-long-period (VLP) seismic signal, as per the study. The experts quickly picked up that the signal was not associated with an earthquake, Popular Mechanics reported. "The signal looked nothing like an earthquake," Stephen Hicks, a co-author of the study from University College London said. "If we were to hear the vibrations from earthquakes, they would sound like a rich orchestra of rumbles and pings. Instead, the symbol from Greenland was a completely monotonous hum … it lasted for nine days."
Strange Seismic Activity
Researchers claimed that the 9-day activity originated from East Greenland specifically due to the glacial thinning happening around the mountaintop, located in East Greenland, according to the study. The glacial thinning triggered a 200-meter-high tsunami, which, as time went on, stabilized into a 7-meter-high long-duration seiche with a frequency (11.45 millihertz). This seiche, a series of oscillating waves in the fjord persisted across the world for nine days.
Scientists Join Hands
Sixty-eight scientists from 40 different countries joined hands to understand this 9-day-long USO event, Popular Mechanics reported. According to investigators, the phenomenon that unfolded in East Greenland was a megatsunami. After finding out the place of origin associated with the strange seismic waves, experts began to work on understanding why the seiche lasted for nine long days. Analysis of the seiche made researchers attribute the long duration of the waves to Dickson Fjord’s unique features. Dickson Fjord has dead ends on its western end and a sharp bend toward the east, facilitating a seiche that can easily escape from the structure and send signals worldwide as it slowly dissipates.
Climate Change
The root cause of the megatsunami has been identified as the glacial thinning occurring around the mountaintop in East Greenland. As per researchers, the glaciers around the mountaintop have thinned by some 100 feet in the last few decades, due to global warming. The altered glacier was simply not enough to hold the weight of the mountaintop situated above it. Considering that no meaningful difference seems to be on the horizon to global warming, it is likely such events will happen again, as per experts. "This event underscores a deeper and more unsettling truth: climate change is reshaping our planet and our scientific methods in ways we are only beginning to understand," Hicks—along with fellow co-author, Kristian Svennevig, with the Geological Survey of Denmark and Greenland shared, The Conversation reported. "Just a year ago, the idea that a seiche could persist for nine days would have been dismissed as absurd… yet, these once-unthinkable events are now becoming our new reality."