Explosive volcanism is equally important as the features of neotectonic and modern movements for the development of the Kurile Islands coast, as it led to the afflux of hundreds of millions of cubic meters of pumisopyroclastic material and tephra into the wave processing zone of coastal zones of the Pleistocene-Holocene. Morphometric, georadar and paleogeographic studies of the coastal-sea relief of Iturup Island allowed to determine several levels of marine terraces in the pyroclastic sediments of the Late Pleistocene-Holocene, and also the presence of a buried sea strait that existed at least in the middle Holocene. Taking into account the values of deformation of the terrace levels, the depth of the strait was 10-15 meters. Volcanic-tectonic deformations connected with eruptions near the central part of the Vetrovoy Isthmus led to the collapse of pumice packs at the section basement of the sea coastal ledge with a layer of beach material on the roof (LU-9223-6320 ± 100, cal. Year BP). Thus, in the mid-late Holocene, after the sea level was risen to the nowadays levels, at least two more pyroclastic series were deposited, the last of which one is dated 1050 ± 70 cal. BP – LU-8685.
The article presents the results of a long-term study of hazardous environmental processes on the Sevastopol coast. Laser scanning allows estimating with high accuracy the natural and anthropogenic dynamics of Sevastopol coast that differ in the concentration of various exogenous processes in relatively small areas and pose a threat to the economic activities of the population. Using laser scanning (lidar shooting), key coastal sections were surveyed in the area of Nemetskaya gully and Uchkuevka beach, where landslide and abrasion processes are displaying. Ground laser survey was performed using a three-dimensional laser scanning system. It was carried out in July 2016, July 2017, July and October 2018. The study showed that the average rate of cliff destruction in the area of the Uchkuevka beach was 0.8 m/year. The maximum cliff destruction rate reached 4.6 m, which was observed in the local ten-meter section of the block slide. Because of terracing, an anthropogenic “cutout” about 150 m long, about 300 m wide and 2.5 to 10 m deep was formed in the area of the Nemetskaya gully. The calculation showed that the Vume of removed soil was 393,649.14 m3, and the Vume of dumped soil on the beach was 28,669.62 m3. The results can be used to monitor hazardous exogenous processes, model and predict coastal development, and make decisions for environmental management in the coastal zone.
Factors affecting the process of postglacial transgression on the shelf and coast of the Primorye (the territory of modern Primorsky Kray) in the Russian Far East are considered. The main regional feature consists in a significant lag of the sea level rise at the beginning of the Holocene following the completion of the Younger Dryas cold stadial. While some researchers explain this phenomenon in terms of descending tectonic movements that predominated in this region over the course of the Cenozoic era, traces of the Holocene climatic optimum sea level highstands along the coastline contradict the conclusion that tectonic submergence was uniform. In order to explain this contradiction, the hypothesis of hydroisostatic load compensation due to the viscoelastic properties of the mantle layers following the end of the last period of glaciation and involving the influx of huge volumes of water to the basin of the Sea of Japan is proposed. Dominating tectonic submergences of the western rim of the Sea of Japan and the Primorye coast were interrupted by hydroisostatic emergence during the Atlantic period between 5-6 ka BP. The use of a computer simulation of postglacial transgression in the SELEN 2.9 and SELEN 4.0 software environments demonstrates a transgression lag under hydroisostatic influence along with the increasing viscosity of mantle layers. The viscosity of mantle layers in the Primorye region is shown to be lower than for the Japanese Archipelago, which is located closer to the recent subduction zone.
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