Mount Asama, straddling Gunma and Nagano prefectures, had a minor eruption early Feb. 2 from its summit crater, sending ash as far as Tokyo and Yokohama in the southern Kanto region, the Meteorological Agency said.

The agency warned of the possibility of large amounts of ash being scattered within a radius of about 4 km from the 2,568-meter volcano's crater due to the minor eruption that occurred at 1:51 a.m.

After the eruption, smoke billowed to heights of about 2,000 meters shortly after 2 a.m. but subsided to around 100 meters above the crater after daybreak, the agency said.

The smoke moved southeastward, and falling ash was observed in Tokyo, and Saitama, Kanagawa and Chiba prefectures, in addition to Karuizawa, Nagano Prefecture, and Tomioka, Gunma Prefecture.

The agency said the situation appeared to be subsiding because the frequency of volcanic earthquakes, believed focused below the crater, eased after the eruption.