A landslide in Greenland that shook the world for nine days
In short: On September 16, 2023, a massive rockslide in Dickson Fjord triggered a seismic event so significant it was detected by stations globally. While it began as a local geological failure, the resulting tsunami and seiche created a unique, long-period vibration that lasted nearly a week.
The event began at 12:35 UTC when a massive block of metamorphic rock—measuring 150 meters thick, 480 meters wide, and 600 meters long—failed on a slope in northeastern Greenland. This initial failure displaced approximately 25.5 x 10^6 cubic meters of material. As the rockslide struck a gully glacier, it transformed into a combined rock and ice avalanche. This mass entered Dickson Fjord, generating a tsunami with a peak height of up to 200 meters (660 feet) and subsequent waves reaching 110 meters, with runup observable 100 kilometers away.
The most unusual characteristic of the disaster was its seismic signature. Because the fjord is narrow, the massive wave was trapped, causing it to slosh back and forth against the walls. This created a large seiche—a standing wave in an enclosed body of water. The vibrations from this motion were so powerful and sustained that they were recorded by seismic stations worldwide for up to nine days. The event was initially mistaken for an earthquake, but it stands as an unprecedented very long period seismic event, with a peak velocity estimated at 42 meters per second.
This disaster serves as a stark indicator of Arctic instability. Greenland is increasingly prone to such events due to rising temperatures, which accelerate glacial retreat and the thawing of permafrost. Permafrost acts as a stabilizer for mountainous terrain; as it melts, the coastal regions become structurally compromised. The 2023 landslide is a primary example of how warming climates can turn geological features into high-velocity hazards, creating tsunamis and seismic disturbances that transcend local boundaries.
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- Summary by Intellect · source: 2023 Greenland landslide
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