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The Water Cycle
Published in Aurèle Parriaux, Geology, 2018
These are small glacial structures that form in a concavity between two rocky ridges converging to a summit (Fig. 7.37), usually on slopes protected from the Sun. They have a compact shape and a small mass. They are in contact with firn (new snow accumulated against and at the foot of slopes) and ice from the walls but separated by a fracture called a bergschrund. Because of their low inertia, many of these glaciers have rapidly disappeared during the warming observed in the Alps beginning in the 19th century. These disappearances have intensified in recent decades.
The Water Cycle
Published in Aurèle Parriaux, Geology, 2018
These are small glacial structures that form in a concavity between two rocky ridges converging to a summit (Fig. 7.36), usually on slopes protected from the Sun. They have a compact shape and a small mass. They are in contact with firn (new snow that accumulates against and at the foot of slopes) and ice from the walls but separated by a fracture called a bergschrund. Because of their low inertia, many of these glaciers have rapidly disappeared during the warming observed in the Alps beginning in the 19th century. These disappearances have intensified in recent decades.
Progressive destabilization and triggering mechanism analysis using multiple data for Chamoli rockslide of 7 February 2021
Published in Geomatics, Natural Hazards and Risk, 2022
Wenfei Mao, Lixin Wu, Ramesh P. Singh, Yuan Qi, Busheng Xie, Yingjia Liu, Yifan Ding, Zilong Zhou, Jia Li
Considering the geometric characteristics of the rockslide body (Figure 9) and the shrinking process of ice cover (Figure 6), the progressive destabilization of rockslide body is shown in Figure 10. When the snow line reached up to the lower part (ice block) of the rockslide body in 2017, surface melting water was likely to percolate into the bedrock and the opened ice-filled joints. The percolating water may have frozen again, and the process of ice segregation could have produced the frost heave (Hallet 1983; Walder and Hallet 1985, 1986) accompanying with the upward displacement of overburden bedrock and the developing of a crack at the top-side of the rock volume. Later, with the freezing-and-thawing cyclic process during 2017–2021, more ice could have filled primarily in the bottom that may have produced rock fractures and joints, giving rise to large fracturing in rock mass. Large amount of snow might have filled in the bergschrund that could enhance the freezing and thawing effect. During thaw cycles, snow melts during summer season, freezes again during winter that change the stress because of volume expansion, which may enhance stress to the frozen rock mass and assist the destabilization of rockslide body. Consequently, the crack got expanded and developed completely and got detached. With the connection of the bottom joints and the bergschrund, the ice segregation effect got enhanced and favoured the lifting of bedrock, which eventually lead to the destabilization of the rock slope.