Mount Asama, which crosses Japan's Gunma and
Nagano prefectures, erupted today (February 2nd) at 01.51 local time, it has been reported.
The Japan Meteorological Agency (JMA) has warned that large deposits of ash could be scattered across a radius of about four kilometres.
Smoke billowed from the 2,568-metre-high volcano and began moving south-east, reports the Associated Press.
The JMA raised its volcanic eruption alert from level two to level three, which prohibits people from going on the mountain.
Mount Asama is one of the most famous mountains in Japan and is the most active in Honshu.
There was widespread destruction and more than 1,500 were killed when the volcano erupted in 1783. Luckily, early-warning systems and technological advances mean a recurrence of such a catastrophe is extremely unlikely.
Other noteworthy eruptions of the volcano took place in 658, 1108, 1783, 1972 and 2004.
There is a volcano observation station operated by
Tokyo University on the mountains eastern slope.
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