Japan's Mt. Asama, which straddles Gunma and Nagano prefectures, erupted Wednesday night, causing forest fires, the Japan Meteorological Agency said.

Forty-eight residents in the village of Tsumagoi at the foot of the volcano evacuated to public facilities, according to local authorities.

No casualties have been reported so far.

The eruption, the first on such a scale since April 1983, occurred around 8 p.m. The agency had set the activity level of the 2,568-meter mountain at 2 on a 6-point scale during the past month, but raised it to 3 following the eruption, saying small- or mid-sized eruptions had occurred and due precautions are needed.

A Tsumagoi village official saw lava on the western slope of the mountain.

The Gunma and Nagano prefectural governments have separately set up disaster management headquarters.

A local meteorological station in Karuizawa in Nagano Prefecture recorded a huge explosion and shock waves at the time of the eruption and microearthquakes were observed.

Confirming the outbreak of forest fires through its monitoring cameras, the agency also warned of falling rocks on the mountain's southern slope within 2 kilometers of the crater. The fires had almost died out later in the day, according to the agency.

The owner of an inn in Tsumagoi said there had been a banging sound followed by earth tremors.

A ranch in the town of Naganohara in Gunma Prefecture, about 20 km north of the mountain, was hit by a shower of molten rock at around 8:50 p.m., police said.

The incidence of temblors has increased since Tuesday afternoon, the agency said, totaling 129 between midnight Tuesday and 11 a.m. Wednesday.

Volcanic ash falls were observed in Tochigi and Fukushima prefectures, the Japan Meteorological Agency said.

The mountain has shown signs of volcanic activity since June 2002 and repeated tiny eruptions occurred between February and April last year.

The volcano is located about 150 km northwest of Tokyo. The upscale summer resort town of Karuizawa is on the mountain's southern slope.

The mountain experienced a major eruption in 1783 and has recorded relatively small eruptions over the past decades. In 1947, 11 mountaineers died after being hit by falling rocks following an eruption. The last major eruption, in July 1990, caused little damage.

Source: Kyodo News