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Kusatsu-Shirane Mt., Japan, 1660s Eruption

Mount Kusatsu-Shirane (36°37′N, 138°32′E) is an active, 2,171m high volcano in Kusatsu, Gunma, Honshu province, some 140 km northwest of Tokyo. It is called Kusatsu Shirane to differentiate it from the Mount Nikkō-Shirane on the other side of the Gunma Prefecture. In the historical times, frequent eruptions occurred there, the last event happened in 1989.

The summit of the Kusatsu-Shirane volcano, located north of the Asama volcano, consists of a series of overlapping pyroclastic cones separated by several crater lakes. The larg-est lake of them is Yu-gama, an acidic turquoise-colored lake with an overlay of yellow sulfur fl oating on its surface. The Kusatsu-Shirane volcano has an andesite–dacite body; the oldest sediments are of Pleistocene age. Southern and south-eastern slopes of the volcano are covered by sintered tuffs and volcanic pumices. The crater was exploited during the intensive sulfur mining in the nineteenth and twentieth cen-turies. A number of fumaroles and hot springs, usually acidic, confi rm the volcano’s geologically young origin. Several volcanic eruptions occurred recently, the strongest one in the crater Yu-gama in October 1932.

The whole range of volcanoes, which creates a certain chain encompassing all the Japanese islands, as well as the deepest parts of the Mariana oceanic trench, are related to the contact zone of the Pacifi c oceanic plate and the Philippine

Sea microplate. In the process of subduction, the Pacifi c Plate plunges under the Eurasian and North American plates. The complex mutual movements resulted in a strong volca-nic activity as well as in many devastating earthquakes in the whole region. The main Japanese volcano chain then contin-ues to the north across the Kuril Islands, Kamchatka, and the Aleutian chain; its other arm stretches to the south of Japan, where it meets with the Australian plate.

Figure 75 presents a report illustration published in the seventeenth century by A. Montanus (1669), who visited the Empire of Nippon (= Japan) as an offi cer of the East Indian Society. In the above composition, the author depicted him-self together with a group of copartners as observers watch-ing the erupting volcano from a safe distance. The engraving was created on a high professional level, and by its technique and compositional maturity, it by far exceeded Japanese iconographical compositions of naturalistic motives of that time. Montanus’ report also brought authentic portraits of local people, landscape paintings, particular customs, and habits and presented a list of trading and business contacts in this – for most Europeans almost inaccessible – distant coun-try. The author provided much valuable information, includ-ing pictorial material about volcanic eruptions and frequent earthquakes in Nippon.

J. Kozák and V. Čermák, The Illustrated History of Natural Disasters,© Springer Science+Business Media B.V. 2010

102 Kusatsu-Shirane Mt., Japan, 1660s Eruption

Fig. 75 View of the Kusatsu-Shirane volcano during its eruption in the 1660s. Copper engraving (Montanus, 1669). Private collection, Prague