Reflection of landslide tsunami in sediment structures: the new GPR data from coastal zone of the Vaigat Strait, West Greenland

The Arctic is warming nearly four times faster than the globe. The drastic consequences of climate change are observed in high mountain areas located within the Arctic coast. This is where permafrost degradation and slope destabilization occur, which can be a direct cause of large-scale landslides. Masses of soil, rocks and sediments reaching the coast cause the formation of tsunami waves, which, reaching the other side of the fjord or strait, destroy infrastructure or affect the development of the coastal zone. An example of this is the Vaigat Strait in western Greenland, where tsunami waves have been observed for several decades. In the last dozen years, the intensity of this phenomenon has increased, which was a direct consequence of, among others, the destruction and displacement of the town of Qullissat on Disko Island. The research in the GLAVE project attempted to read the record in sediments located in areas flooded by tsunami waves. For this purpose, the commonly known GPR method was used, but with the use of a modern GPR set consist of the Mala Ground Explorer and 450 MHz shielded antenna, which provides high-resolution radar data. The 2D/3D profiles were supplemented with information from trenches and shallow boreholes made at the intersection of the profile lines. Preliminary results indicate that each tsunami wave reaching the opposite coasts of the Vaigat Strait leaves behind evidence in the form of specific sedimentological structures. The interpretation of the obtained new GPR data supported by information from possible dating can indicate contemporary and historical tsunami episodes. The conducted GPR studies can support landslide monitoring conducted in threatened areas and more accurately predict the threat from the occurrence of sudden tsunami waves to the environment and the local community.