The development of lake-swamp environments and the impact of natural catastrophes on the ecosystem over 9670 cal yr BP are reconstructed based on biostratigraphic studies (diatom and pollen analyses) of the valley peat bog at the bottom of the Baransky volcano in the mountainous part of the Iturup Island. During this time, the peat bog was twice overtopped by lahars created by the descent of the crater lake as a result of strong earthquakes. The results of Bayesian modeling carried out based on radiocarbon dating data allowed one to determine the ages of the lahars as ~6020 and 4170 cal yr BP. The section includes 14 tephra interlayers from large eruptions of nearby volcanoes. Frequent volcanic ashfalls resulted in increased watering of the swamped valley. Changes in biotic components have been detected, including damage to woody vegetation on slopes, moss cover loss, changes in acidity or alkalinity of the geochemical environment, and development of pioneer communities on the new substrate. Short-period climatic rhythms have been reconstructed and their relationship with global and regional events has been analyzed. The stages of bog ecosystem development, periods of decreasing and increasing watering up to the formation of a shallow water body have been established. Temperature fluctuations and variations in the amount and composition of precipitation, including heavy snowfalls, had a great impact on the development of the biota. Multidecadal events have been revealed and their connection with changes in solar activity and processes affecting the cyclogenesis in the Pacific region has been shown.
Razjigaeva et al. (2025) studied this question.