Landslide Susceptibility of the Territory with Gas-Hydrothermal Manifestations (A Case Study of the Geysernaya River Valley, Kamchatka)

The Geysernaya River valley in Kamchatka, known for its unique hydrothermal manifestations, has experienced activation of slope processes, mainly landslide ones, in recent decades. Three large landslides that occurred in 1981, 2007 and 2014 led to significant changes in the morphology of the valley and the activity mode of some geysers. The article presents an assessment of the susceptibility of the Geysernaya River valley to landslide development, performed using the landslide susceptibility modeling (LSM) approach based on the RandomForest algorithm. Unlike traditional landslide hazard assessment methods, LSM analyzes spatial relationships between past landslide occurrences and a range of natural factors. The model incorporated geological, geomorphological and hydro-geomorphological characteristics, as well as surface thermal anomalies derived from Landsat-8 data for 2017–2021, minus topographic effects (i.e., only as a consequence of the earth’s heat flow, albedo and weather differences). The modeling results indicate that the most landslide-hazardous areas are concentrated along the left side of the Geysernaya River valley within fault zones (mainly along the circular fault of the caldera edge), elevated thermal anomaly zones (∆T > 5°C) and at the contact between weakly lithified volcanogenic–lacustrine deposits (tuff sandstones, tuff gravelites and tuff siltstones) and more resistant extrusive rocks (dacites and liparites). Also, high landslide probabilities are noted on the right side of the valley in the near-edge parts of the Krugloe Plateau and the Geysernaya Extrusion. At the same time, the Shumnaya River valley segment, characterized by similar geological and geomorphological conditions, but lacking active gas-hydrothermal vents, exhibits significantly lower landslide susceptibility values. Here, the near-edge parts of the Shirokoe and Krugloe Plateaus within the considered valley area are most susceptible to landslide processes. Heterogeneous lithology is one of the most essential predictors of landslide susceptibility for both valleys.