The Japan Meteorological Agency warned Sunday of a possible small eruption at Mt. Io, which straddles the southwestern prefectures of Miyazaki and Kagoshima, after observing an increase in volcanic earthquakes.
The local government in Ebino declared a 1-kilometer no-entry zone around the crater of Mt. Io, part of the Kirishima mountains, while the weather agency said that large stones could be ejected within a 1-km radius in the event of an eruption.
The agency detected 50 volcanic temblors by 3 p.m. Sunday at the 1,317-meter volcano, the highest per day since it set up seismometers there in March 2013.
Volcanic activity has intensified since last year, the agency said. In addition to volcanic quakes, fumarolic gas was observed in December and areas with high ground heat have been expanding.