Geoinformation analysis of the spatial variability of the Raikoke island (Kuril islands) geosystem

Abstract

Volcanic eruptions significantly transform natural geosystems, which is most characteristic of components such as terrain, flora and fauna. The theoretical significance of this research lies in acquisition of new knowledge that contributes to a deeper understanding of response of natural environment to consequences of volcanic eruptions of various types and power. The practical significance is due to possibility of using the obtained results in substantiating assessment of volcanic hazard territories and compiling corresponding maps. Eruptions of the Raikoke volcano are rare, but all recorded facts of activity are characterized as strong, and significantly changed appearance of Raikoke Island. The research used satellite images from Sentinel-2 and Landsat satellites. Spatial dynamics of coastline was studied on the basis of synthesized images (NIR-SWIR-RED). In the research of vegetation transformation, time series of normalized relative vegetation index (NDVI) was used. We analysed the time course of changes in the area of Raikoke Island, the maximum and average NDVI values within its limits from 1972 to 2021, and also compiled a schematic map of the dynamics of the components of the geosystem of Raikoke Island. Grass and grass-shrub vegetation covered about 80 % of total area of island in 2018. The areas devoid of vegetation cover are confined to large mobile talus slopes, beach, marginal parts of lava flows around perimeter of the island, as well as large block mass collapse of crater floor. As of 2021, the closed vegetation cover occupies no more than 0.03 % of the island’s area and is fragmentally located in central part of southern slope, lower parts of eastern, northern and western slopes. An analysis of eruptive activity of the Raikoke volcano and the time course of NDVI suggests that it will take about 100 years for vegetation cover occupy an area comparable to area before eruption of 2019.