Showa-Shinzan is a dome on the east flank of Usu stratovolcano. Showa-Shinzan has an interesting history. Since the eruption occurred during the height of World War II, there was no official record of the growth of the dome. The local postmaster, Masao Mimatsu, placed a piece of paper on his window. On the paper he drew the profile of Showa-Shinzan at different times as the dome grew. The area was uplifted steadily from January 1944 to November 1944. In November, lava broke through to the surface. By September of 1945, the dome and central plug had grown 1,300 feet (400 m) above ground level. Note that steam is rising from the dome.
Location: 42.5N, 140.8E
Elevation: 2,400 feet (731 m)
View a slide show of the growth of Showa-Shinzan.
The growth of Showa-Shinzan was accompanied with explosive eruptions, phreatic eruptions, pyroclastic flows, and mudflows. The eruption caused damage and fatalities.
Showa-Shinzan lava dome.
Showa-Shinzan lava dome.
Showa-Shinzan lava dome.
Sources of Information:
Francis, P., 1994, Volcanoes a planetary perspective: Oxford University Press, New York, 443 p.
Minakami. T., Ishikawa, T., and Yagi, K., 1951, The 1944 eruption of Volcano Usu in Hokkaido, Japan: Bulletin of Volcanology, v. 11, p. 45-160.
Simkin, T., and Siebert, L., 1994, Volcanoes of the World: Geoscience Press, Tucson, Arizona, 349 p.