Comparison of periglacial processes in permafrost and seasonal frost environments

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-Does the presence of permafrost reinforce geomorphic processes?-What does permafrost melting induce geomorphic processes?In an attempt to answer these questions, field monitoring on rock weathering and soil movements were undertaken on mountains in Japan, central Europe, Svalbard and Tibet. The monitoring sites consist of similar sedimentary geology while differ in ground thermal regimes. The monitoring sites underwent also investigations on ground internal structure, hydrology and snow conditions. These data were integrated to evaluate the effects of the presence and long-term evolution of permafrost on geomorphic changes, which led to the following conclusions.1.Monitoring of temperatures, moistures and ground movements (frost wedging, frost heave and solifluction) on rockwalls and debris slopes indicates seasonal variations in ground movements associated with ground thermal and moisture conditions.2.Investigations of rock mass discontinuity and soil structure indicate that the rate of rock fall on the rock mass strength depends also on joint spacing while that of solifluction on the near-surface thickness of fine soil.3.Sounding of internal structure by electric, seismic and thermal methods as well as direct drilling show the distribution and depth of permafrost at regional scales. In the European Alps and eastern Tibetan mountains, which are located at the marginal permafrost conditions, rapid degradation of permafrost and corresponding deepening active layer have recently progressed, causing either acceleration or deceleration of periglacial processes.4.Integrating the extant and new data on periglacial processes leads to numerical models of ground movements as a function of the temperature, moisture, ground materials and topography.