Cornice accretion, cracking and failure along with their meteorological controls at Gruvefjellet, Central Svalbard

Abstract

The cornice development, accretion, cracking and eventual failure of cornices along the ridgeline of the Gruvefjellet plateau mountain and their controlling meteorological factors was studied in the two consecutive snow seasons 2008/2009 and 2009/2010. Three automatic time lapse cameras have been used and 45 field trips were carried out up to the Gruvefjellet plateau to investigate the ongoing process dynamics. These natural processes endanger infrastructure and inhabitants of Nybyen which is part of Longyearbyen, Svalbard’s main settlement located at 78° N in the High Arctic. Throughout the two investigated snow season 180 cornice failures were recorded and collected in a cornice database. 70 failures were categorized as “D2 R3” avalanches and larger and displayed distinctive cornice fall avalanches. The geomorphological impact of cornices is considerable in this High Arctic setting. During the process of cornice cracking considerable amounts of debris rip off from the headwall, accumulate in the opening crack and are eventually released by cornice fall avalanches. Thus cornices display active transport agents of debris from the plateau edge to the basal slope and contribute to the formation of talus cones. In addition an extensive literature review on cornice development is given.