Hachijo-jima VulkanHachijo-jima volcano (八丈島, Hachijōjima) forms an 14 km NW-SE elongated island in the central Izu Islands about 300 km south of Tokyo. It consists of 2 small overlapping, mainly basaltic stratovolcanoes (Higashi-yama and Nishi-yama).
The last eruptions were from the younger Nishi-yama volcano in the 15th century and occurred from the summit and submarine vents.
Beschreibung:The older of the 2 volcanoes is the eroded Pleistocene-to-Holocene Higashi-yama volcano on the SE end of the 14-km-long island.
The younger and historically active is the symmetrical Nishi-yama volcano the NW end. Flank cones occur on the SE flank of Nishi-yama. The small volcanic island of Ko-jima lies several km to the west of Hachijo-jima and probably represents a flank vent or an older predecessor volcano of Nishi-yama.
Higashi-yama began erupting several tens of thousands of years ago and formed 2 small calderas. Nishi-yama volcano started to grow from below sea level about 10,000-8,000 years ago.
(Source: Smithsonian / GVP volcano information)
A magnitude 6.6 earthquake hit 60 km SE of Hachijo-jima volcano on 13 August 2009.
2002 earthquake swarm
An earthquake swarm began at Hachijojima volcano on 13 August 2002 and lasted until around 21 August. On 15 August earthquakes occurred 2 km off the western shore at depths of 5-15 km.