Evidence of Quick-Clay Deposit at Kangerlussuaq, West Greenland

In 2007 a large Ice dammed lake at the Russel Glacier, near Kangerlussuaq, West Greenland, drained in a catastrophic flood event – a jökulhlaup. The draining was made possible by a general retreat of the glacier due to climate amelioration. Under normal circumstances such jökulhlaups go relatively unnoticed in Greenland, but in this case the jökulhlaup propagated through a river basin which passes by the main international airport in Greenland. Due to the erosion of the riverbank during the jökulhlaup, several man-made structures were affected – roads disappeared and several storage facilities were eroded and destroyed by the river. In the wake of the catastrophic flood, a previously unknown permafrozen fingrained marine deposit was observed in the erosional bank of the river. Laboratory studies have proven this material to have extremely high sensitivity, with natural water content much higher than the liquid limit. The formation has been stabilized by the presence of permafrost in the area, but the combination of erosional energy supplied by the river and the sensitive properties of the material have resulted in quick thaw, destabilization and erosion of the formation. As an effect, the riverbank was eroded approximately 40 m inland over the course of the jökulhlaup, which lasted approximately one day. It is the first time such a quick clay formation has been observed very near surface in inhabited areas in Greenland. If such deposits are found to be more widespread, it could be very problematic for the future infrastructural development in the region. Here we present the results of recent research, including a study of mineralogy of the quick clay using SEM and XRD. We also discuss the effect of climate warming on permafrost thaw in the area.