Temporal and spatial variations in periglacial soil movements on alpine crest slopes

Abstract

AbstractThis paper describes up to ten years of continuous monitoring of frost heave, creep and associated parameters on high mountain crest slopes in the Japanese and Swiss Alps, aiming to evaluate spatial and interannual variations in the rates and controls of soil movement. Shallow frost creep reflecting diurnal frost heave activity dominates the crest slopes that lack a vegetation mat and have a thin debris mantle with good drainage. Seasonal frost heave activity can induce slightly deeper movement where fine soil exists below the depth reached by diurnal freeze–thaw penetration, although the shallow bedrock impedes movements below 20 cm depth. As a result, downslope velocity profiles display strong concavity with surface velocities of 2–50 cm a−1. The frost creep rates vary spatially, depending on the soil texture, slope gradient, frequency of temperature cycling across 0 °C and moisture availability during freeze–thaw periods. Soil movements recur in every freeze–thaw period, although with some interannual variations affected by the length of seasonal snow cover and the occurrence of precipitation during freeze–thaw periods. The Swiss Alps encounter more significant interannual variations than the Japanese Alps, reflecting the large variability of the annual snow regime. Copyright © 2005 John Wiley & Sons, Ltd.