While residents in the landslide-hit area of western Greenland remain evacuated, experts are attempting to find reasons for the natural catastrophe at the Karrat Fjord.
Three adults and a child missing since the tsunami hit the Nuugaatsiaq settlement on Greenland's northwestern coast on Saturday are now presumed to have died in the disaster, news agency Ritzau reported Tuesday evening.
Eye witnesses on a boat are reported to have seen a large dust cloud from distance at the time of the landslide on Saturday evening.
The location of the witnesses is aiding experts in the analysis of the incident, seismologist Peter Voss of the Geological Survey of Denmark and Greenland (GEUS) told broadcaster DR.
“Eye witnesses saw something come out of the mountain, then they saw a huge dust cloud. Afterwards, investigation of the area showed that a large section slid down into the fjord. That started a very large wave which spread throughout the entire fjord system,” Voss said.
But Voss told DR that experts were uncertain as to what had set off the landslide.
“Our next job will be to sort through the measurements. Measurements of earthquakes and landslides resemble each other. We have to find out what started the landslide – whether or not it was an earthquake,” he said.
Experts initially believed the tsunami to have been started by an earthquake, but GEUS began to doubt this after receiving reports of tidal waves 30 kilometres away.
Reports on Sunday suggested an earthquake measuring 4.0 on the Richter scale had struck off the Greenland coast.
Trine Dahl Jensen, a senior researcher with GEUS, told Ritzau on Sunday that earthquakes of that magnitude were “not normal” in western Greenland.
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“A good guess is that it set off a landslide which started the tsunami. That has been seen in Greenland before,” Jensen said.
The researcher added that Greenlanders were used to experiencing tsunamis caused by icebergs – but not by landslides hitting the sea.
“An earthquake as small as the one we measured cannot give rise to so much water,” Voss told DR on Monday.
The seismologist added that he expects it to take some time to give definite answers on the cause of the landslide.
Further landslides in the area could not be ruled out, Voss said.
78 people have been evacuated from the settlement, along with a further 75 from two other nearby settlements, to Uummannaq, Greenland's eleventh-largest town, where they are being accommodated in a community centre.
11 buildings in Nuugaatsiaq were washed away by the waves.