19 June 2017
Nuugaatsiaq: A large landslide-induced tsunami on Saturday night?
Late on Saturday the small community of Nuugaatsiaq in west Greenland was struck by a large but isolated tsunami. The aftermath of this event was captured on a Youtube video that has been widely reported:
Information about this event remains quite sketchy, but the English language media reports indicate that four people may be missing. It appears that the local seismological bureau recorded the event as a magnitude 4.0 earthquake, with the tsunami striking a few minutes later. Greenland is not a particularly seismically-active area, and as far as I can tell this earthquake has not been recorded more widely. This, combined with the localised nature of the tsunami, suggest that the cause is most likely to have been a very large landslide, either from the fjord walls or under the water (or maybe both). News reports in Greenland (in Danish) also speculate that the cause may have been a mass movement:-
It is still uncertain what caused the devastating tidal wave that hit Nuugaatsiaq on Saturday night, says a seismologist from GEUS [The National Geological Surveys for Denmark and Greenland].
“We have some signals at our earthquake stations resembling earthquakes, but they might also indicate that a landslide has been triggered,” says seismologist Peter Voss, from GEUS. He explains that GEUS has a theory that it is a major slope from a mountain that has triggered the tide of waves:
“The slump has made a large part of the mountain collapse into the fjord and has created this wave,” says Peter Voss.
But GEUS can not conclude anything from the measurements alone…He also tells that the landslide could have been underwater, and then it will be difficult to detect.
Clearly the priority yesterday was to provide assistance to the affected villages, but news reports indicate that they will start to try to identify the source today. This is important, given the potential for a secondary failure if a landslide was the cause.
This is the Google Earth image of the area affected by the tsunami:
Hopefully more information will emerge about this event today.