Sunday, Sep 02, 2012
Aerial monitoring conducted by the Japan Coast Guard (JCG) on August 26th revealed a previously unobserved circular area of light green discolored water measuring approximately 900 m in diameter about 1,300 m southeast of Aogashima Island’s southern edge at a depth of 63m. Large areas of light-brown and light-green discolored water were seen around the island’s northern coast, and light-brown and light-green discolored water were also seen around its southeastern coast, these discolorations had previously been observed on a small scale. ... [more]
Aoga-shima volcano eruptions
stratovolcano 423 m / 1,388 ft
Izu Islands, Japan, 32.45°N / 139.76°E
Eruption list: 1781-85, 1670-80, 1652, 600 BC ± 200 years, 1100 BC ± 300 years, 1200 BC ± 50 years, 1800 BC ± 100 years
Similarly, on 18 April 1785, strong strombolian eruptions resumed and built a second cone in the crater. The eruption caused 130-140 fatalities (although details are not known), while 163 residents escaped to Hachijo-jima Island. The eruption also produced lava flows inside Ikenosawa Crater.
From historic documents, it seems that by 1787 the eruption had ended.
Takada et al (1992) "Geology of Aogashima Volcano, Izu Islands, Japan", Bulletin of the Volcanological Society of Japan 37(5), pp. 233-250