In Alaska, the project 2004 Forest Fire Impacts to Hydrological Cycles, Permafrost and Eco Systems in Central Alaska has continued since 2005 to monitor permafrost conditions after a severe wildfire (M. Fukuda, K. Harada, Y. Sawada, K. Narita, and M. Ishikawa).
In the summer of 2007, observations were carried out at Poker Flat near Fairbanks in July and August and at Kougarok near Nome in August. The observations included electrical soundings and pit surveys for monitoring active layer conditions, and vegetation surveys. The active layer thicknesses increased in the 2007 summer. Comparing the data for the last three years, the thermal condition in the active layer will be estimated and the effect of the wildfire on the permafrost condition and vegetation recovery will be clarified. In June 2007, rock glaciers in the Brooks Range were also studied (A. Ikeda). The distribution, structure and thermal conditions of the rock glaciers, investigated in the arid part of Alaska, were compared with those in relatively warm and humid mountains, to clarify the environments indicated by rock glaciers.
The Japan-Norway joint project has continued in Svalbard since 2004 (N. Matsuoka, A. Ikeda, M. Ishikawa, T. Watanabe, H.H. Christiansen and O. Humlum). In the summer of 2007, data on several periglacial processes (ice-wedge cracking, rock weathering and rock glacier creep) were collected from the model experimental sites in Adventdalen. The monitoring network was further expanded to the Kapp Linné area, to compare periglacial dynamics between inland (Adventdalen) and maritime (Kapp Linné) situations. GPR sounding was also undertaken on the polygonal ground in the two areas, to distinguish polygons with ice-wedges and those with only active-layer soil wedges.
In the Daisekkei Valley (a Pleistocene glacial trough), northern Japanese Alps, the present-day rockfall activities were investigated to produce a geohazard map for safe recreation (Y. Kariya, J. Komori, T. Kawasaki, Y. Matsunaga, K. Mokudai, Y. Miyazawa, M. Ishii, G. Sato and S. Iwata). The location, size and lithology of all debris deposited on perennial snowpatches in the valley floor were determined monthly from May to November 2006, and the debris production rates were computed. Snow ablation, precipitation and rock temperatures were also monitored. Preliminary results were presented in the journal Landslides (Kariya et al.) and in the 2006 AGU fall meeting (Kawasaki et al.).
In the alpine and subalpine zones of the northern Japanese Alps, geology and geomorphology of landslides were investigated by a combination of fieldwork and laboratory analysis (G. Sato and Y. Kariya). The landslides were mapped using aerial photographs and DEM-generated shaded maps. The timing of landslides was determined by volcanic ash deposits and 14C ages. Part of these features may have been associated with deglaciation or permafrost thawing during or after the Lateglacial period. New depression (sagging) features have also been monitored with extensometers in an alpine area of the southern Japanese Alps, following a rock slope failure during the thawing period of 2004 (R. Nishii, N. Matsuoka and A. Ikeda).
The Japanese highest mountain, the Fuji volcano (3776 m asl), has steep, slippery upper slopes. During warm periods in winter and early spring, rainfalls often trigger snow-debris avalanches at around 2500 m asl, which move downslope as rapid slush flows until reaching 1300 m asl (see photo). Detailed field investigations in the winter of 2006-2007 showed that the seasonal frost table within loose volcanic materials acted as a slip plane that released a snow-debris avalanche: the debris volume reached 105 m3 per event (J. Komori, S. Anma, K. Honda and T. Hiishi).
The colloquium on cryosphere geo- and bio-sciences in Japan held three scientific meetings in Tokyo. The colloquium also hosted two field workshops on active patterned ground in the Ou Mountains and on relict blockfields in the Kanto Mountains (Leader: M. Seto).