September 16, 2023 Tsunami: Dickson Fjord, Greenland

Reference #13737 states (unofficial translation):

On Saturday morning, a small tsunami was recorded in Dickson Fjord close to Ella Ø in the national park in Northeast Greenland […]

The investigations indicate that parts of a mountain have fallen into the water, which has thus triggered a small tsunami that has hit Dickson Fjord and Ella Ø. Among other things, the tsunami has hit the Sirius Patrol's station, where some material has been washed into the water. However, the station was abandoned for the season. There were therefore no people present, and therefore no injuries.

Reference #13738:

In September 2023, we observed an unprecedented global 9-day-long 10.88 mHz (92 s) monochromatic very-long period (VLP) seismic signal, originating from East Greenland. We demonstrate how 25 M m3 of rock detached from a mountain and entered Dickson Fjord, triggering a 200 m high tsunami.

Reference #13816:

On 16 September 2023, a mass-wasting event occurred at 12:35 UTC in East Greenland, where a rockmass on an area of 1:6 × 10^5 m2 and a height of 50–100 m detached and impacted initially to the west, falling around 300–400 m in a slope of 30°–40° […] The dark discolored coastal regions in post-tsunami Sentinel-2 and Dove data suggest peak tsunami runups exceeding 200 m near the entry point and an average of ∼60 m along a 10 km long profile.

Reference #13837:

this event started with a glacial thinning–induced rock-ice avalanche of 25 × 106 cubic meters plunging into Dickson Fjord, triggering a 200-meter-high tsunami.

no such events have previously been observed in East Greenland

On 16 September 2023 at 12:35 UTC (11:35 local East Greenland time), a 25 × 106 m3 rockslide (29) (supplementary text S1) occurred on a mountain peak at Hvide Stovhorn 1200 m above Dickson Fjord.

[…] the rock-ice avalanche may have triggered a submarine landslide in a sediment cone deposited at the terminus of the gully glacier.

The 16 September 2023 landslide-tsunami event generated substantial seismic ground motions. At nearby stations (e.g., DK.SCO, 300 kmaway; Fig. 1B), we observed an emergent 200-sduration high-frequency (HF) (2- to 10-Hz) arrival with an extended coda, accompanied by a 60-s duration signal at lower frequencies (LF) (17 to 100 mHz).

The impact of the 16 September 2023 rock-ice avalanche into the 540-m-deep and 2.7-kmwide Dickson Fjord triggered a tsunami with an initial backsplash with a runup height of ~200 m and subsequent waves up to 110 m high.

At the Nanok station and research base at Ella Ø, 72 km away out-fjord, the tsu nami had a local runup height of 4 m, inun dating up to 80 m inland, and destroying infrastructure valued at nearly 200,000 USD.

Elsewhere in the fjord system, near-coastal cultural heritage sites, such as Thule Culture Inuit archaeological sites and 20th-century trapper huts, were well within the inundation reach and were assumed to be destroyed. The observed destruction of an old trapper hut at Kap Hedlund (Fig. 1C), which had never been affected by tsunamis during its century-old history, demonstrates the historically unprecedented magnitude of the September 2023 event.

The tsunami evolved into an initially 7-m-high, ~90-s-period freely oscillating seiche that decayed slowly owing to the confined nature of the fjord and could be detected seismically for 9 days.

Reference #14052:

Using satellite imagery, both observe an initially 200 m run-up height near the location of the slide, with an average of 60 m run-ups being observed through the remainder of the fjord for the September 16th event