The Air Force Weather Agency reported that plumes were visible on satellite imagery emanating from Kikai during 24-28 May. The thin plumes drifted to the S on the 24th, SE on the 25th and 26th, S on the 27th, and E on the 28th. The plumes were estimated to be lower than 3 km a.s.l. Ash was seen from the island of Yaku-shima on 26 May during 1600-1800. After 29 May the area was covered with meteorological clouds, preventing satellite observations.

Geological Summary. Kikai is a mostly submerged, 19-km-wide caldera near the northern end of the Ryukyu Islands south of Kyushu. It was the source of one of the world's largest Holocene eruptions about 6,300 years ago when rhyolitic pyroclastic flows traveled across the sea for a total distance of 100 km to southern Kyushu, and ashfall reached the northern Japanese island of Hokkaido. The eruption devastated southern and central Kyushu, which remained uninhabited for several centuries. Post-caldera eruptions formed Iodake lava dome and Inamuradake scoria cone, as well as submarine lava domes. Historical eruptions have occurred at or near Satsuma-Iojima (also known as Tokara-Iojima), a small 3 x 6 km island forming part of the NW caldera rim. Showa-Iojima lava dome (also known as Iojima-Shinto), a small island 2 km E of Tokara-Iojima, was formed during submarine eruptions in 1934 and 1935. Mild-to-moderate explosive eruptions have occurred during the past few decades from Iodake, a rhyolitic lava dome at the eastern end of Tokara-Iojima.

Source: US Air Force Weather Agency