Grishin S.YU., Belousov A.B., Belousova M.G., Auer A., Kozyrev I.A.
Vulkanologiya i sejsmologiya 2021; 15(6): 30-42
The short-term violent explosive eruption occurred on June 21, 2019 at the small volcanic island Raikoke located in the central part of Kurile Island arc. The climactic stage of the eruption lasted 3.5 h, producing the ash cloud up to 13 km high. We have analyzed a set of satellite images of the volcano as well as conducted a field work in order to investigate pyroclastic deposits of the eruption and to determine its impact on ecosystems of the island. We have found that the eruption had phreatomagmatic Subplinian – Plinian character. The rising magma batch of basaltic andesite composition interacted with groundwater that was probably represented mainly by seawater that precipitated into the volcanic edifice through permeable rocks of the volcanic island. Tephra and numerous pyroclastic flows of the eruption emplaced the hot deposits that covered the whole area of the island, killed vegetation and destroyed rookeries and colonies of marine animals. The largest volume of the pyroclastic material was deposited mostly as pyroclastic flow fans at the foot of the volcanic cone, so the coastline moved in the sea and the area of the island increased up to 15%. During the first year after the eruption, the friable pyroclastic deposits were intensively eroded and redeposited, forming new beaches on the island coast. The recovery of the Raikoke ecosystems will be associated with the continuing erosion of the pyroclastic substrate accompanied by gradual recolonization of the island by birds and by natural introduction of new plant species. Patches of the survived vegetation will accelerate the plant succession. In general, the ecosystems of the island experience strong periodic destructions by strong explosive eruptions followed by relatively fast periods of recovery, which are interrupted then by a new eruption.
