More dynamic than expected: An updated survey of surging glaciers
in the Pamir

Goerlich, Franz; Bolch, Tobias; Paul, Frank

doi:10.5194/essd-2020-79

Cited by 3 publications

(1 citation statement)

References 39 publications

(75 reference statements)

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“…The north west of the Pamir system shows a particulary high density of surging glaciers (Goerlich et al, 2020), spatially correlated with the occurrence of soft and fine-grained sediments like limestone, claystone, sanstone, conglomerates, aleurolite, gypsum and marl (see geological map by Ibrohim et al). The Western Petra Pervogo range is composed mainly of Cretaseous-Neogene sedimentary rocks.…”

Section: Geologymentioning

confidence: 99%

Glacier detachments and rock-ice avalanches in the Petra Pervogo range, Tajikistan (1973–2019)

Leinß¹,

Bernardini²,

Jacquemart³

et al. 2020

Preprint

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Abstract. Glacier detachments are a rare phenomenon of glacier instability, whereof only a handful have been documented to date. Common to all known cases are the large detached volumes of many million cubic meters of ice and long runout distances. Recently, two detachments of smaller size were observed in the Petra Pervogo range, north west of the Pamir mountains, Tajikistan. Using a variety of satellite images, we identified in total 9 detachments and several ice and rock avalanches which occurred in four different catchments between 1973 and 2019. The avalanche run out distances vary between 2 and 19 km and detached volumes range between 2 and [8.8 × 106] m3. Seven out of nine detachments occurred between July and September in years with temperature above the past 46-years trend. No active glacier surge was observed immediately before detachment, but elevation model (DEM) differences indicate a surge-like behavior about 10 years before the two largest detachments. Instead, one glacier retreated before detachment while the other remained stagnant before increased sliding pronounced the impending detachment. To put results into a regional context, we analyzed DEM differences over the entire Pamir range and found 237 surging glaciers, predominantly in the north-western part where soft and fine-grained rock-types are common. We are confident that no major events were missed due to lack of satellite data, because destroyed vegetation remains visible in the normalized difference vegetation index (NDVI), several years after large mass flows, e.g. about 10 years for the Kolka–Karmadon rock-ice avalanche. From the large number of detachments which occurred under very similar conditions we conclude that rising temperatures combined with soft, fine-grained sediments are very critical components favouring the detachment of entire valley glaciers.

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Section: Geologymentioning

confidence: 99%