Raikoke stratovolcano is located in the Central Kuril Islands, with a height of 551 m (or 2500 m from the bottom of the sea), it has a crater on its peak with a diameter of 700 m and a depth of 200 m, the composition of its rocks is andesites. The island-volcano Raikoke together with the underwater volcano 3.18 is a single volcanic massif of 19×8 km in size, the distance between their peaks is about 7 km. The relative height of the underwater volcano from the bottom of the sea is about 900 m, its top is at a depth of about 250 m, the composition of the rocks of the underwater volcano is andesibasalts and andesites. There were only two known strong eruptions of Raikoke: in 1778 and on 15 February 1924. The current explosive eruption of Raikoke volcano began at 18:05 GMT on 21 June 2019. The first message about the eruption was transmitted by Tokyo VAAC; the information about the development of the eruption based on various satellites was obtained by us using the information system “Remote monitoring of the activity of volcanoes of Kamchatka and the Kuriles (VolSatView)”. According to the Himawari-8 satellite data (http://volcanoes.smislab.ru/animation/1561927182.webm), the main phase of the eruption began with a series of large explosions that raised ash to 10–13 km above sea level, and lasted about 15 hours, forming a powerful eruptive cloud moving over 2500 km North-East from the volcano. On 30 June, the aerosol clouds from Raikoke were observed at distances from the volcano: 3100 km (Novosibirsk Islands), 3500 km (Lake Baikal), about 5500–6000 km (Northwest Canada). A detailed analysis of satellite information suggested that on 24–25 June a lava flow began to pour out on the western slope of Raikoke. It is also possible that during the eruption of Raikoke, the underwater volcano 3.18 also erupted.

Owing to modern development of information technologies and computer simulation systems, and datasets derived from open historical meteorological data archives, it appeared possible to perform retrospective analysis of large explosive volcanic eruptions. This work analyzes the results of simulation of the events associated with the eruptive cloud propagation during the catastrophic eruption of the November, 1964 Sheveluch volcano. The obtained additional eruptive cloud parameters enabled us to reproduce the dynamics of the explosive eruption and to validate its magmatic genesis.

Strong explosive volcanic eruptions are extremely dangerous to the modern jet aircraft as they can produce several cubic kilometers of volcanic ash and aerosols that can be sent to the atmosphere and the stratosphere in several hours to several days during the eruption. In 2016, five from thirty active volcanoes erupted in Kamchatka (Sheveluch, Klyuchevskoy, Bezymianny, Karymsky, and Zhupanovsky) and three from six active volcanoes in the Northern Kuriles (Alaid, Ebeko, and Chikurachki). Effusive volcanic activity was noted at Sheveluch, Klyuchevskoy, Bezymianny and Alaid. All the volcanoes produced explosive activity. Strong explosive events occurred at Sheveluch mainly from September till December. Moderate ash emission had accompanied of Klyuchevskoy’s eruption through March till November. Explosive activity at Karymsky, Zhupanovsky, Alaid, and Chikurachki volcanoes was observed mainly in the first half of the year. The total area covered by ash in 2016 was estimated 600,000 km2, from which 460,000 km2 were related to the eruptions of Kamchatka volcanoes and 140,000 km2 were attributed to the eruption of the North Kuriles volcanoes. The activity at Sheveluch, Klyuchevskoy, and Zhupanovsky was dangerous to international and local airlines as explosions produced ash up to 10-12 km above sea level. The activity at Bezymianny, Karymsky, Alaid, Ebeko, and Chikurachki posed a threat to local aircrafts when explosions sent ash up to 5 km above sea level.