Moraine destabilization leading to the 2013 landslide onto Svínafellsjökull glacier, SE Iceland

<p>On February 27<sup>th</sup> 2013 a large landslide fell onto Svínafellsjökull glacier, on the western slope of Öræfajökull volcano, SE Iceland. The slide occurred during an intensive rainstorm event between February 24<sup>th</sup> and 27<sup>th</sup>. The slide was detected at 20:30 o’clock at a seismic station located several kilometres away. It originated from lateral moraine and talus material below the steep north-eastern slope of Mt. Skarðatindur above a small contributory glacier. The debris flowed down-glacier towards the west with an approximate runout distance of 3000 m and a width of 500-600 m, covering about 1,4 km<sup>2</sup> or about 17% of the glaciers’ surface. The extent of the debris deposit suggests a highly water saturated debris flow. Based on Digital Elevation Models (DEMs) from 2011 and 2013 the estimated volume of the slide was 5,4±0,1 million m<sup>3</sup> which makes it one of the largest debris slides in Iceland over the last decades. <br>Long term destabilization by glacier unloading was investigated by comparing DEMs from 1994 to 2011. Meteorological data suggests that record breaking amounts of precipitation in combination with snowmelt due to relatively warm temperatures in late February caused a significant water inflow into the system which is likely to have caused the failure. <br>Analysis of aerial imagery and DEMs after the failure suggest a complex slide. The debris cover on the glacier reduced the surface ablation which resulted in an up to 30 m height difference between the debris free glacier surface and the debris covered part in 2020.</p>

Erosion processes on different relief units: the relationship of form and process

Geomorphological relief units are related to certain processes and the history of their development. They are well defined by form and material. This study investigates erosion processes on different relief units. Rainfall simulations, rill experiments and monitoring by aerial photography were performed on dunes, glacis, Holocene fillings, talus material and Quaternary loam terraces in order to analyse the varying process intensities. Splash, interrill erosion and runoff generation were quantified by rainfall simulation experiments, rill erosion by rill experiments and gully growth by monitoring over several years. The test sites are situated in NE- and SE-Spain, S-Morocco and N-Burkina Faso. The results clearly show that the measured processes are very different from those supposed to be relevant for the formation of relief units. Dunes and Holocene fillings are highly erodible by splash and interrill erosion. In contrast, Quaternary loam terraces show a low susceptibility to erosion processes. We conclude that the relief units show very different dominances of erosion processes and process intensities. The differentiation is more significant with increasing scale and complexity of the erosion process: The extent of gully growth varies much more between the different units than those of splash and interrill erosion do.