# Greenland fjord landslide set off a 92-second seismic signal for nine days, SWOT satellite data show

- Published: 2026-11-14 04:15 UTC
- Section: Planet › Earth sciences
- Tags: Dickson Fjord, 92-second seismic signal, Greenland landslide, seiche, SWOT satellite, satellite altimetry, very-long-period signal, glacier thinning, Nature Communications
- URL: https://realtech.media/news/rt-890f51da7494e96876201bb5_greenland_fjord_landslide/

**A rockslide into a Greenland fjord set off a standing wave that rang Earth's crust every 92 seconds; SWOT radar mapped the water motion from orbit.**

![Greenland fjord landslide set off a 92-second seismic signal for nine days, SWOT satellite data show](https://realtech.media/media/2026/11/31799fedb7da8a8d.webp)
*futura-sciences.com*

Instruments thousands of miles apart registered a low-frequency seismic signal with a steady 92-second interval for up to nine days after a mountainside collapsed into Dickson Fjord in East Greenland on September 16, 2023, according to futura-sciences.com [1]. The cause was traced to water trapped in the fjord, and in 2025 satellite radar confirmed it directly [1].

## The collapse and the trapped wave

An estimated 25 million cubic meters of rock fell and picked up glacier ice on the way down. It entered the water as a mixed avalanche and drove water more than 200 meters (650 feet) up the adjacent slopes [1]. Lead author Kristian Svennevig, writing in Science, documented an average runup of 60 meters along 10 kilometers of the fjord. A second, smaller landslide struck the same site on October 11 [1].

Angela Carrillo-Ponce showed in The Seismic Record that a sharp bend near the fjord outlet blocked the wave. Unable to escape into the open sea, the surge turned into a standing wave, a seiche [1]. The water rocked across the channel, and each impact against the rock walls sent low-frequency seismic waves through the planet at the same 92-second interval [1].

## Radar from orbit

Researchers first inferred the wave mechanics from land-based sensors. Direct evidence came later: in Nature Communications (June 3, 2025), Thomas Monahan and colleagues used data from the SWOT satellite to build two-dimensional maps of the fjord surface [1]. The radar showed water surface tilts of up to two meters across the fjord, reversing with each swing [1].

The team combined the satellite passes with seismic data from Alert, Canada, and calculated the initial wave amplitude at 8 meters (26 feet). Weather and tidal models showed that neither wind nor tides caused the motion [1].

The authors separate two figures. The 650-foot value is local runup on the steep cliffs near the collapse zone. The 26-foot value is the height of the standing wave over open water, and it is this wave that drove the global seismic signal [1].

The researchers point to progressive glacier thinning at the mountain base as the main driver of the failure [1]. Monahan noted that satellite altimetry now offers a way to measure enclosed water bodies worldwide. The immediate trigger at the cliff face remains unmeasured [1].

## Sources

1. [futura-sciences.com](https://www.futura-sciences.com/en/in-september-2023-seismometers-around-the-world-picked-up-a-signal-that-repeated-every-90-seconds-for-nine-days-it-came-from-a-remote-fjord-in-greenland-c1_902506/)
2. [dailygalaxy.com](https://dailygalaxy.com/2026/11/greenland-earth-pulse-92-seconds-nine-days)

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Source: RealTech, realtech.media — https://realtech.media/news/rt-890f51da7494e96876201bb5_greenland_fjord_landslide/