In September 2023, a massive landslide in Greenland generated a seismic signal, detected globally for nine days.
Dickson Fjord - Image Wikimedia
A volume of 25 million m³ (880 million ft³) of rock and ice collapsed into the remote Dickson Fjord in eastern Greenland, triggering a 200-meter (656-foot) high tsunami. This tsunami caused oscillations in the fjord for several days, forming a phenomenon known as a "seiche." The movement of these water masses generated unusual seismic waves, recorded worldwide, from Greenland to Antarctica, emitting a curious harmonic hum.
Surprised by these signals, seismologists collaborated with researchers from different fields. An international team comprising 68 scientists from 40 institutions and 15 countries was formed to investigate the event. They cross-referenced various data sources: seismic recordings, infrasound sensors, satellite images, and tsunami simulations. Photographs of the area, taken by the Danish Army a few days after the collapse, were also used to assess the damage.
The investigation revealed that the mountain, which once towered 1.2 km (3,937 ft) high, collapsed due to glacier retreat caused by climate change. The volume of collapsed rock was gigantic, equivalent to 10,000 Olympic swimming pools or 220,000 semi-trailers, a line of trucks stretching 3,700 km (2,300 miles)! The resulting tsunami is one of the most impressive observed in recent years. Positioned 70 km (43 miles) away from the collapse site, 4-meter (13-foot) waves damaged a research station and destroyed several archaeological and cultural sites.
Luckily, Dickson Fjord, which is usually frequented by cruise ships, was deserted at the time of the tsunami. The conclusions of this study highlight the connection between natural events occurring in remote areas and their global impacts. They also underscore the central role of climate change in such disasters, reminding us of the importance of better anticipating these events to protect populations and ecosystems.
References:
Kristian Svennevig
et al.,
A rockslide-generated tsunami in a Greenland fjord rang Earth for 9 days.
Science 385,1196-1205(2024).