Activity of geomorphological processes on the slopes of river valleys in the conditions of gas-hydrothermal occurrences (based on multi-temporal images and DEM analysis)

Abstract

In the geothermal zones of modern volcanic areas, geomorphological processes are considerably influenced by numerous gas-hydrothermal outcrops, which may dramatically change rock properties and, consequently, denudation peculiarities and rates. The activity of processes on the slopes of Kamchatka river valleys under conditions of gas-hydrothermal occurrences (Geysernaya river valley) and without them (Shumnaya river valley) has been studied and comparatively analyzed. For the most correct separation and comparison of the valley regions which differ in the conditions of development of the modern slope processes, ArcticDEM digital elevation model and a series of morphometric maps (slope steepness, exposition, elementary watersheds) built on its basis, as well as geological maps, results of thermal survey of different detail level and field observation data were used. Interpretation of high spatial resolution images (0.5–5 m) for the mid-1960s (KeyHole-4 CORONA) and modern images for the period 2016–2021 from different survey systems was carried out. As a result of decoding, quantitative assessments of slope conditions within the selected valley fragments selected on the basis of morphometry were obtained for two time slices separated by 55 years. It is established that under conditions of gas-hydrothermal manifestations development, the share of the total area of the slope’s sections affected by active processes, with other conditions being equal, is significantly higher than the same in the areas without gas-hydrotherms. For 55 years the share of the areas with slope processes activation on the background areas practically has not changed, and on the territories affected by gas-hydrothermal influence has increased by 10–17 %. The conducted studies allow us to conclude that gas-hydrothermal manifestations are the most powerful driver of modern geomorphological processes on slopes in the studied region.