The geomorphological impact of the 1967 Steinsholtshlaup Glacial Lake Outburst Flood

The overall aim of this paper is to assess the present day geomorphological record of the 1967 Steinsholtshlaup in Iceland to understand better the event and the hazards it generated, its long-term legacy and the implications for both landscape interpretation and hazard planning in areas of contemporary valley glaciation. The 1967 landslide was a complex paraglacial response to decades of down wasting of the Steinsholtsjökull glacier. The rockslide incorporated glacier ice, then swept into a proglacial lake and a confined pro-glacial valley, leaving a trail of ice, rock debris and landscape transformation. About 5 km from the site of the collapse, boulders up to 80 m3 in size were scattered immediately beyond the confluence of the proglacial valley with a wide sandur. A paper published by Kjartansson in 1967 recorded the immediate aftermath of the GLOF, but left many questions unanswered, and there have been no subsequent publications.

A better understanding of this event is important because, circumstances similar to those found in the Steinsholtsdalur valley prior to 1967 have developed in numerous glacial environments around Iceland’s ice caps.  As in many other mountain areas, increased temperatures over the last deccadees have driven renewed and rapid retreat of valley glaciers. Across Iceland, existing proglacial lakes have expanded, and many new ones have formed. These glacier fluctuations have affected the stability of neighbouring mountain slopes, which are resulting in slope deformation and mass movements. The potential for a major geomorphological incident in areas that both attract tourists year-round and have seen a recent related infrastructure development raise serious concerns and stresses an urgent need to study and monitor these environments.