Mount Aso in southern Japan erupted early Saturday, belching a column of ash several thousand metres (feet) into the air, the latest eruption in one of the world's most volcanically active countries.
Japan Meteorological Agency issued its third-highest alert, warning people not to approach the volcano after it rumbled to life at 1:56 am (1646 GMT Friday).
The meteorologists warned of a heavy ash fall within 30 kilometres (19 miles) northeast of the mountain, with moderate and light ash falls forecast up to 250 kilometres away over the next few hours.
Mount Aso's huge caldera dominates the southwestern main island of Kyushu, where the 1,592-metre (5,253-foot) volcano is a popular tourist spot.
Mount Aso previously erupted in September last year, rumbling to life after being dormant for 19 years.
Japan, with scores of active volcanoes, sits on the so-called Pacific "Ring of Fire" where a large proportion of the world's quakes and volcanic eruptions are recorded.
On September 27, 2014, Japan suffered its deadliest eruption in almost 90 years when Mount Ontake, in central Nagano prefecture, burst unexpectedly to life.
An estimated 63 people were killed in the shock eruption which occurred as the peak was packed with hikers out to see the region's spectacular autumn colours.
Japan has around a dozen volcanic warnings in effect at present.