Lessons worth highlighting
Members of our group were amongst the first to publish positive results of employing the surface-based GPR method for investigating a rock glacier [LG00] and were probably the first to report poor results [MMHG06]. The study of the Furggwanghorn rock glacier is a second example that reveals potential limitations of the method as applied to rock glaciers. For the practitioners of geophysical techniques, we suggest that case studies that include negative results are as useful as those that describe only positive results.
In addition to supplying dependable images of the subsurface, the H-GPR method has three noteworthy advantages:
It does not require the snow cover required for efficient surface-based geophysical surveying a rock glacier.
It can be applied in many areas that are challenging or hazardous to explore using surface-based techniques; as well as rock glaciers, such areas include many mountain slopes, debris avalanches, scree slopes and rockfalls.
For large regions, it is much faster and less expensive than the surface-based GPR method; areas requiring several weeks to survey on the ground could be surveyed by a helicopter mounted system in a single day.
Recent rapid developments of unmanned aircraft may soon make it possible to conduct 3D surveys using a drone mounted GPR system.
Acknowledgments
We thank Sarah Springman and Thomas Buchli from the Institute of Geotechnics, ETH Zurich, Switzerland for their contributions to this project. Furthermore, we owe thanks to the various field crews, GEOSAT, SA, Sion, Switzerland for acquiring the helicopter data and the Landmark Graphics Corporation for providing data processing software through the Landmark University Grant Program. This study received funding from the ETH CHIRP Grant 1-01-09-3, and Canton Wallis, Switzerland, represented by Charly Wuilloud, is also thanked for financial contributions.