Distribution of pingos on Svalbard

Abstract

The present study explores the formation, preservation and degradation of pingos in High Arctic environments, which are controlled by the interplay of permafrost, hydrology and climate conditions. The analysis of aerial and satellite images and digital elevation model data revealed 136 pingo mounds on Svalbard Archipelago. The pingos are distributed at elevations from 0 to 201 m above sea level (asl) with a median of 42 m asl. Of those, 44 pingos are found above and 92 below the maximum level of the respective local Holocene transgressions. All pingos were found in terrain favorable for the formation of hydrologically sourced open-system pingos. Based on published geological data, at least 55 pingos locate near geological faults that presumably allocate sub-permafrost waterflow feeding the pingos. With maximum and mean heights of 40 m and 9.4 m, respectively, Svalbard pingos generally have larger diameters and reach mean heights twice those found in other Arctic regions, such as the predominately closed-system pingos of Northern Alaska and the North-east Siberian lowlands. The comparison of aerial photographs of 1936–1938 with aerial photographs of 2008–2012 of Svalbard pingos exhibit no change in the general morphology of the pingos during the last about seven decades. There are exceptions - four pingos have formed on Little-Ice-Age (LIA) moraines following the local retreat of glaciers, and one pingo – the Riverbed pingo – formed in Adventdalen after 1936. The pingo growth once initiated is dynamic with height gains of up to 1 m annually, but obviously stops within several years or decades. Today, 21 pingos continue to show activity by the outflow at perennial subpermafrost springs. Dried thermokarst craters were found on top of 19 pingos of all sizes and geomorphological positions, while 11 water-filled craters were found only on large pingos with heights exceeding 12 m. Transitional landforms (flattop pingos and platforms) were identified. These landforms may point to underground ice intrusions that do not reveal themselves as classical pingo mounds.