Detecting and quantifying mountain permafrost creep from in situ inventory, space-borne radar interferometry and airborne digital photogrammetry

Abstract

In this paper three different techniques for detecting and quantifying mountain permafrost creep are compared: (1) rock glacier inventory and characterization from in situ indicators, (2) space-borne radar interferometry, and (3) digital processing of repeated airborne imagery. The specific characteristics of the three methods and their complementarity are investigated for the Fletschhorn mountain range in the Simplon/Saas valley region, Swiss Alps. We found that radar interferometry is suitable to quantify the degree of activity and the order of surface velocity of rock glaciers over large areas in one process, with the possibility to also detect very small movements of inactive and relict rock glaciers. On the other hand, aero-photogrammetry represents a valuable base for additional interpretation of the three-dimensional surface flow field (including speed, direction and change in thickness) of the most active rock glaciers. Results from radar interferometry can also form the basis for further detailed in situ investigations.

Acknowledgment

ERS SAR data courtesy AO3-178, © ESA, processing GAMMA. JERS SAR data courtesy J-2RI-001, © NASDA, processing GAMMA. SAR data analysis supported by the ESA Data User Programme. Aerial imagery used in this study taken by the Swisstopo and Swiss Federal Office of Cadastral Surveys. The expenses of the in situ rock glacier inventorying were partly covered by the ‘Dr Joachim de Giacomi’ research fund of the Swiss Academy of Sciences (SAS). Swiss topographic map reproduced by permission of the Swiss Federal Office for Topography (BA024706).