Mount Kirishima continued erupting Thursday on the border between Kagoshima and Miyazaki prefectures, spewing columns of smoke up to more than 2,500 meters, the weather agency said.
Rocks were blasted as far as 8 km from Kirishima's Shinmoedake peak, according to the Meteorological Agency. Volcanic ash disrupted train and flight services in the area.
The agency revised the scale of the eruption upward to "medium" from the initial "small," after the smoke columns reached about 500 meters higher than Wednesday.
While continuing regulations to keep people away from the volcano, the agency also warned of large volcanic rocks falling in areas about 2 km from its crater.
Volcanic tremors indicating magma activities also continued Thursday.
The first in-depth eruption began Wednesday at around 7:30 p.m., when the 1,421-meter Shinmoedake peak began spewing debris in its second outburst since a small eruption Jan. 19, the agency said.
According to the Miyazaki Observatory, ash is falling on a wide area that includes the cities of Miyazaki and Nichinan in Miyazaki Prefecture, and has partially closed expressways in Kyushu. Fourteen residents in the town of Takaharu, Miyazaki Prefecture, voluntarily evacuated to a public facility early Thursday.