A tsunami caused by a landslide in a Greenland fjord shook the Earth for 9 days

In September 2023, a tsunami triggered by a landslide in a Greenland fjord shook the Earth for nine days. According to a publication by 60 international scientists in the journal Science, the tsunami was caused by global warming and could be expected to recur.

The collapse of a mountain followed by a landslide in a fjord on the east coast of Greenland created a tsumami over 100 m high. The particularly large volume of 25 million m3 is equivalent to 15 times the volume of the Eiffel Tower, or the disappearance of the last 200 m of the Mont Blanc. Even more exceptional, the tsunami was trapped in a part of the Fjord, and the wave that went back and forth between the two shores every 90 seconds generated an oscillation of the Earth at the same period, a vibration that was detected by all the world’s seismometers, and this "abnormal" signal was visible for over 9 days. It is one of the "strangest" seismic signals ever recorded.

While seismology enabled the event to be detected and dated, the location of the collapse was then determined by analysis of satellite images, as well as on-site investigations (by boat and drone).

The catastrophic collapse is very impressive in its size, its equivalent in the Alps would have a "return time" of the order of a century. The causes of the collapse, in addition to the progressive damage to all mountains, are accentuated by the reduction in permafrost at the summit and the size of the glacier at its base. Climatic conditions comparable to the 1,000 m high mountain in Greenland are found in the Alps, approximately above 3,000 m, and in the Himalayas, above 5,000 m. In these two great massifs, an equivalent collapse is therefore not unthinkable on the scale of a human lifetime (there are even equivalents in the Himalayas).

References

Kristian Svennevig et al., A rockslide-generated tsunami in a Greenland fjord rang Earth for 9 days. Science 385, 1196-1205 (2024). DOI:10.1126/science.adm9247