20 June 2017

Nuugaatsiaq tsunami: details emerge of the landslide

Posted by Dave Petley

Nuugaatsiaq tsunami: details emerge of the landslide

In the last 24 hours details have started to emerge about the very large landslide that triggered the Nuugaatsiaq tsunami in Greenland on Saturday, which is now known to have killed four people, with a further nine people injured, two of them seriously.

The landslide occurred on Karrat Fjord, which according to Google Earth is the area shown below (although the location is far from clear at present).  Nuugaatsiaq is in the north of this image, on the plateau with the aeroplane symbol.

 Nuugaatsiaq tsunami

The location of the landslide that triggered the Nuugaatsiaq tsunami, via Google Earth.

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The landslide was reportedly 1,000 metres in length and 300 metres in width.  A helicopter video has emerged of the site of the landslide:

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The full version of the video may be available via the Facebook embed below:

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This image from the video suggests that the landslide may have been very deep-seated, and thus high volume, but we will need a better image of the slide to determine this properly:

Nuugaatsiaq tsunami

The scar of the landslide that triggered the Nuugaatsiaq tsunami; still from a Facebook video

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It remains unclear as to whether this landslide was triggered by the reported earthquake, or whether the seismic event was the signal from this landslide.  My sense remains that the latter is the most likely, but we await details of the seismic signal to know.

But perhaps the biggest current issue is the discovery of another potentially unstable slope immediately adjacent to the mass that has failed.  This is clearly shown in the video:-

Nuugaatsiaq tsunami

The potentially unstable rock mass adjacent to the landslide that triggered the Nuugaatsiaq tsunami; still from the Facebook video

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Clearly there is the potential for a further large landslide from this slope (although failure is not inevitable).  The plan is that one of the naval ships in the area will now keep a watch on this slope.  There is a need to establish proper monitoring at this location as a matter of some urgency.  In consequence the settlement of Nuugaatsiaq has been completely evacuated, and both Illorsuit and Viaqornat are being evacuated as well.