Landslide and tsunami in the Karrat Fjord 2017

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The landslide and tsunami in Karrat Fjord 2017 occurred in mid-June 2017 in northwest Greenland and resulted in the deaths of four people.

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On the evening of June 17, 2017, a landslide occurred on the southern slope of the Umiammakku Nunaat peninsula ( → map ). Several dozen million cubic meters of rock and slope sediments were set in motion. A large part of this mass fell into the Kangilleq fjord , triggering a tsunami that moved westward into the fjord complex of the Karrat fjord . The tidal wave, which was initially over 90 meters high, reached Nuugaatsiaq , located about 32 kilometers west-southwest, after about seven minutes with a wave height of about ten meters. The tsunami dragged four people out to sea who have since been considered dead. Furthermore, seven people were slightly injured and two people seriously injured. Eleven buildings were destroyed. Rescue helicopters brought the 200 or so residents who were found on site to the district capital, Uummannaq .

Both the landslide and the tsunami were recorded by the Nuugaatsiaq seismic monitoring station. The signal reached the station at 23:39  UTC (21:39 local time) and lasted for several minutes.

Further effects

In addition to Nuugaatsiaq, floods caused by the tsunami were also reported from Illorsuit , Niaqornat and Uummannaq, where only property damage occurred. However, Illorsuit and Niaqornat were also completely evacuated. The residents of Saattut , Qaarsut , Ikerasak and Ukkusissat were also alerted. The Danish Air Force provided a Lockheed C-130 Hercules for relief operations. Also, Air Greenland and ferries brought assistants to the affected areas. Due to concerns about further tsunamis, it was recommended not to sail in the fjord area.

Investigation of the termination point

In July 2017, three weeks after the incident, the area was flown over with a helicopter and oblique aerial photos of the demolition site were taken. From the photogrammetric aerial photographs , Gauthier et al. a digital terrain model of the slope and compared this with an elevation model that had been recorded before the event, which made it possible to estimate the mobilized volume. At the point of the demolition, the steep and unglaciated mountain flank rises more than 2100 m above sea level, spanning a horizontal distance of about 3100 m. The landslide broke off roughly in the middle of the slope, so that the fall height of most of the material was over 1000 m. The upper limit of the mobilized mass was over 1200 m and the main mass was 800 m wide and up to 300 m thick. Gauthier et al. estimate that around 58 million cubic meters of rock and slope sediments were mobilized in the event, of which up to 45 million cubic meters reached the fjord. They characterize the event as an “extremely fast rock avalanche” lasting less than five minutes.

Later developments

On June 24, 2017, the evacuation for Niaqornat was lifted. In March 2018, Illorsuit and Nuugaatsiaq were still abandoned. A Swiss company observed the situation and found that the mountain slipped about an inch every day and another landslide could be expected at any time. The risk of this was rated 11.5 out of 12, which is why a repopulation of the two villages was further excluded at this point in time. In August of the same year it was discovered that the mountain had meanwhile slipped further. Experts from the Geological Research Institute for Denmark and Greenland (GEUS) should reassess the situation, since at best the evacuation for the less damaged Illorsuit could be canceled. Shortly thereafter, however, it was announced that there was still danger from the mountainside, making it impossible to lift the evacuation.

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  1. ↑ Erin Bessette-Kirton, Kate Allstadt, Jana Pursley, Jonathan Godt (2017): Preliminary analysis of satellite imagery and seismic observations of the Nuugaatsiaq landslide and tsunami, Greenland. USGS . Washington, DC (archived).
  2. ↑ Christoph Seidler (2017): Landslide and huge tidal wave on Greenland: The 95-meter tsunami. Spiegel Online , accessed September 22, 2018.
  3. ↑ John Clinton, Tine Larsen, Trine Dahl-Jensen, Peter Voss, Meredith Nettles (2017): Special event: Nuugaatsiaq Greenland landslide and tsunami. Incorporated Research Institutions for Seismology.
  4. ↑ Anthony Lomax (2017): Nuugaatsiaq Greenland landslide and tsunami: Seismograms suggest several stages of land failure. Quake Stories.
  5. ↑ A huge landslide generated tsunami waves damaging some villages in Greenland - 4 people (remain) missing. At: earthquake-report.com.
  6. ↑ Niaqornat bliver evakueret. In: knr.gl .
  7. ^ Tsunami strikes Nunavut's neighbor Greenland. At: nunatsiaqonline.ca.
  8. ↑ Dave Gauthier, Scott A. Anderson, Hermann M. Fritz, Thomas Giachetti (2018): Karrat Fjord (Greenland) tsunamigenic landslide of June 17, 2017: initial 3D observations. In: Landslides 15 (2), pp. 327-332.
  9. ↑ Hermann M. Fritz, Thomas Giachetti, Scott A. Anderson, Dave Gauthier (2017): Field Survey of the 17 June 2017 Landslide and Tsunami in Karrat Fjord, Greenland. Abstract NH12A-01 presented at the American Geophysical Union's Fall Meeting 2017 in New Orleans December 11-15, 2017.
  10. ↑ Evakuerede kan vende hjem. At: knr.gl.
  11. ↑ Tsunami: Fortsat høj risk ved Karrat-fjeldet. In: Sermitsiaq .
  12. ↑ Nyt fjeldskred: Evakuerede øjner've om at vende tilbage. In: Sermitsiaq.
  13. ↑ Beredskab: Fortsat høj fare for fjeldskred i Karratfjorden. At: knr.gl.