Abstract
Strong earthquakes could serve as a trigger for glacier detachment and associated ice–rock avalanches. The 1988 Tsambagarav earthquake (M = 6.4) initiated collapse of part of the glacier tongue and a further ice–rock avalanche with an abnormal 5 km long path in Zuslan valley, Tsambagarav ridge (Mongolian Altai). Early documentation of surface effects in 1988, remote sensing and field data gathered 16 and 30 years after this event allowed for the assessment of the seismic impact on a reduction of “damaged” glacier under conditions of global warming as well as estimating topography changes in this arid and seismically active area. Because of the earthquake, the glacier immediately lost 10.4 % of its area (0.1 km2 of tongue surface). Additionally, 56% of its area was lost during 1988–2015, shrinking much faster than neighboring glaciers of similar size and exposition. Collapse of snow–ice cornice in the accumulation zone could play a key role in rapid acceleration of the detached ice block and abnormally long path of the ice–rock avalanche. A large amount of debris material provided more than 16 years of ice melting. Downstream, the valley avalanche debris cover repeats the topography of underlying Pleistocene moraines, which should be considered in regional paleogeographical reconstructions.
Highlights
The modern retreat of glaciers and intensive transformation of alpine landscapes in arid Central Asia, as well as in other high mountain regions, are caused by the ongoing global warming
Before the 1988 Tsambagarav earthquake, glacier No 15 was a cirque glacier with a hanging tongue, which was less than one third of the length of the entire glacier
A chain of processes initiated by the 1988 Tsambagarav earthquake, triggered an ice–rock avalanche in the Zuslan valley (Mongolian Altai)
Summary
The modern retreat of glaciers and intensive transformation of alpine landscapes in arid Central Asia, as well as in other high mountain regions, are caused by the ongoing global warming. The retreat of glaciers in the Altai, the northern flank of the Central Asian mountain belt, has been observed since the end of the 19th century and has recently significantly accelerated [1,2,3,4,5]. In Mongolia, the average annual temperature has increased by 2.1 ◦ C since 1940 This has been accompanied by aridity intensification—the annual precipitation has decreased by. 7% according to IRIMHE (the Information and Research Institute of Meteorology, Hydrology and Environment of Mongolia) [6]. Such climate changes do not contribute to the preservation of glaciation in the center of the largest continent of the Earth. Within the Mongolian Altai, the area of glaciers—one of the main sources of fresh water in the region—is steadily decreasing [5,7,8,9]
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