On 29 May the Fukushima Local Meteorological Observatory reported that seismic activity increased slightly beneath Azuma during May. The Coordinating Committee for the Prediction of Volcanic Eruptions' seismic network detected 51 small-magnitude volcanic earthquakes during 21 and 22 May and 39 on 21 May (the most recorded in one day since November 1998). During March four low-frequency tremor events were recorded, while 40 were detected in April.

Geological Summary. The Azumayama volcanic group consists of a cluster of stratovolcanoes, shield volcanoes, lava domes, and pyroclastic cones. The andesitic and basaltic complex was constructed in two E-W rows above a relatively high basement of Tertiary sedimentary rocks and granodiorites west of Fukushima city. Volcanic activity has migrated to the east, with the Higashi-Azuma volcano group being the youngest. The symmetrical Azuma-Kofuji crater and a nearby fumarolic area on the flank of Issaikyo volcano are popular tourist destinations. The Azumayama complex contains several crater lakes, including Goshikinuma and Okenuma. Historical eruptions, mostly small phreatic explosions, have been restricted to Issaikyo volcano at the northern end of the Higashiyama group.

Source: The Japan Times