Japan Coast Guard announced that Nishinoshima of Ogasawara Islands expanded over 10 times the area than the island before the eruption because of the photography from the sky. Ogasawara islands are 1,000km away south-southeast from the Tokyo mainland. Nishinoshima started to erupt last November and keeps spreading today. When the aero plane of Japan Coast Guard observed on December 24, Mt. Nishinoshima had shot volcanic conglomerates from the crater several times a minute.

This island erupted in 1973 and once expanded the area. In 2013, this island erupted again. Now this is 2.29 km² which is 49 times the area than Tokyo dome.

Japan Coast Guard says that they can confirm red magma, so the island is continuing to supply magma. A ship which navigates neighborhood should be more careful.

Kenji Nogami, the professor of Tokyo Institute of Technology said if lava mound prevents a way of magma, an explosive eruption might happen in a flash.