How a landslide in Greenland shook the Earth for 9 days

The Earth shook for nine days in 2023. The signal was first detachable on September 16, and it soon faded but remained detectable for nine entire days. But what exactly caused this nine-day earthquake? Well, scientists finally have an answer.

According to a new paper published in the journal Science, researchers believe that a landslide in Greenland caused the earthquake. More specifically, the landslide caused water to slosh from side to side across the 2.7-kilometer-wide Dickson Fjord.

The Dickson Fjord is located in eastern Greenland, and researchers believe that a massive landslide triggered a 110-meter-high tsunami wave. This tsunami continued to slosh back and forth for several days, resulting in the aforementioned nine-day earthquake.

While scientists were quick to figure out that the landslide was to blame, they weren’t quite sure why the wave within the Dickson Fjord continued to rock for so long. See, when bodies of water are high by disturbances like this, they can sometimes generate what we call a seiche—a standing wave of sorts.

Image source: Paul / Adobe

Usually, these waves dissipate quickly. However, the seiche generated in the Dickson Fjord that day persisted for several days despite quickly reaching levels that couldn’t even be detected by a small naval boat passing through the area. So why did this one keep rocking, and why did that cause a nine-day earthquake?

The scientists involved in the research believe it was likely partially due to the shape of the fjord, the bottom of which is rounded and likely acted as a “rocking chair” for the water to move around with very little resistance. This meant a lot of energy was trapped in the water, thus causing it to rock back and forth for so long instead of dissipating as rapidly as usual.

As for the landslide that began it all, researchers believe it was a direct result of climate change. As the glacier near Dickson Fjord has thinned and melted, the mountainside has become less stable. Part of it eventually gave way, dropping 25 million cubic meters of rock into the fjord, setting off a chain reaction that led to the nine-day earthquake.