Comparison of resistivity and radio-echo sounding on rock glacier permafrost

Abstract

Several rock glaciers in the Swiss Alps have been probed qualitatively and quantitatively for permafrost by means of geoelectrical and radio-echo soundings. These techniques were often combined with seismic and BTS-soundings and, in order to get reference data, also applied to surrounding areas and materials (bedrock, talus cones, and glacier ice). All the applied methods proved to be economic and reliable. The experience obtained in the field work as well as in the interpretation of the data is displayed in detail. For thickness estimates of rock glacier permafrost, resistivity soundings tend to give minimum values, and seismic refraction soundings maximum ones. High ice contents in the perennially frozen sediments investigated are indicated by the various methods. The existence of such supersaturated permafrost seems to be quite typical for arctic and alpine permafrost environments. However, resistivity and radio-echo soundings show the lack of a major core of massive ice in the rock glaciers. The investigated rock glaciers originate at the base of talus slopes - a most common situation in the Alps as well as in many other parts of the world - and they are undoubtedly creep henomena of supersaturated hich-mountain permafrost.