On 16 September 2023, a significant landslide, consisting primarily of ice and rock, occurred in Dickson Fjord, triggering a 200-meter-high tsunami.

However, the tsunami was not immediately observed due to a seiche formation. A seiche is a standing wave oscillating back and forth within a confined body of water, such as a fjord. In this case, the seiche phenomenon caused the tsunami wave to be trapped and amplified within the fjord for approximately nine days, resulting in unusual seismic readings worldwide.

Links:
Bizarre, nine-day seismic signal caused by epic landslide in Greenland

Greenland mega-tsunami led to week-long oscillating fjord wave