The small island of Nishinoshima was enlarged when several new islands coalesced during an eruption in 1973-74. Another eruption that began offshore in 2013 completely covered the previous exposed surface and enlarged the island again. Water discoloration has been observed on several occasions since. The island is the summit of a massive submarine volcano that has prominent satellitic peaks to the S, W, and NE. The summit of the southern cone rises to within 214 m of the sea surface 9 km SSE.
A submarine explosion from Nishino-shima breaches the surface on October 9, 1973. Steam trails behind individual ejected hot blocks at the margin of the plume. Submarine eruptions began on April 12, 1973. On September 11 a new island was first seen. Lava flows began in September, and three new islands were formed, which joined together during October-November 1973 forming Nishino-shima-shinto. The new island itself was connected to the pre-existing Nishino-shima Island by wave activity after the eruption ended.
Photo courtesy of Japan Meteorological Agency, 1973.
Last updated 2021-08-15 13:00:02