Recent geophysical, geomorphological and geodetic surveys of Montasio occidentale glacier (Julian Alps, Italy)

The glaciers of the European Alps are currently affected by large mass losses, due to unfavorable climatic conditions. Glacier areas and volumes rapidly decrease and the bedrock tends to outcrop, causing morphological changes and fragmentation of most ice bodies. However, different glaciers are reacting in different ways to the same climatic forcing. Investigations on small ice bodies have a particular significance in this context, since they largely contribute to the total loss of glacier area, due to their large number and rapid shrinkage. In addition, they can provide important insight into processes governing glacier wastage and into snow redistribution by wind and avalanches, since they allow detailed investigations. In summer 2010 a specific field campaign was carried out on Montasio Occidentale Glacier (W.G.I. number I4L0003005), a 0.07 km2 avalanche-fed ice body located in the Italian Julian Alps (Eastern European Alps). The "niche" glacier is exposed to north and its altitude averages 1940 m a.s.l., ranging from 2105 to 1880 m a.s.l.. The purpose was to assess its current status (surface topography, total area and volume, degree of activity and alimentation) and possible peculiarities in the reaction of this glacier to current climatic changes. Indeed, processes and feedbacks governing mass exchanges in this kind of low-altitude, avalanche-fed glaciers are still somewhat unknown. In addition, the Julian Alps are characterized by very high precipitation amounts and differences in climatic sensitivity are very likely to exist with respect to drier areas of the Alps. The Montasio glacier was completely surveyed by a Terrestrial Laser Scanner in September 2010, obtaining a high resolution Digital Elevation Model (cell size 20 x 20 cm). Additional information like reflectivity and RGB values associated to the TLS survey allowed us to distinguish and map the different substrata (snow, firn, debris) which cover the ice body, and to automatically delineate the glaciated area and the surface features. Geophysical investigations were also performed, to investigate the internal structure of the glacier and its depth. Measurements were carried out along longitudinal and transversal transects using a radar system equipped with a 75 MHz and a 200 MHz antennas. The EM image of the subsurface highlighted several reflecting surfaces within the glacier body and at the boundary between the ice and the underlying bedrock. Geomorphological investigations were performed in the glacier area and in its foreland, in order to make a detailed geomorphological map. The glacier is bordered by a prominent frontal moraine, cut to the right and left sides by meltwater gullies, almost inactive. Some other outer, minor moraine ridges are present at lower altitude; they formed during stadial phases and are currently covered by a soil. On the glacier, in a middle position, a squeeze moraine outcrops. The first results of our observations confirm a peculiar behavior of Montasio glacier with respect to the most part of alpine glaciers. In particular, its mass seems to be stationary or slightly increasing in the latest years, in response to recent snowy winters and in spite of current warm summers. This first dataset will constitute the basis for future work. Our intention is to reconstruct the glacier evolution since the Little Ice Age and to continue the monitoring of this ice body to evaluate its behaviour in the coming years