(TOKYO) -- A Japanese volcano in the southern Kyushu region erupted Wednesday, leaving fields in nearby towns coated with ash and prompting limited voluntary evacuations overnight.
Heavy clouds of smoke spewing from the Shinmoedake volcano on Mount Kirishima prompted the Japan Meteorological Agency to raise the volcanic alert level to a 3, warning people to clear the area within a mile of the volcano.
Agency volcanologist Sei Iijima said the eruption did not pose a threat to nearby cities, and a major eruption was not imminent, as of now.
"You can never say never with a volcano," Iijima said. "But the lack of magma movement beneath the surface leads us to believe that this activity won't lead to a large-scale eruption."
The volcano, one of 20 inside Mount Kirishima, began erupting around 7:30 Wednesday morning.
By 3 p.m., heavy smoke could be seen billowing nearly 5,000 feet above the crater.
That prompted the meteorological agency to raise the alert level.
Air space above the mountain remained open but the haze prompted airlines to cancel at least four domestic flights from the Miyazaki Prefecture Thursday, while the buildup of ash on train tracks forced Japan Rail to cancel several train lines in the region.
Roads were shut down because of poor visibility. Start times for three junior and elementary schools in the city of Miyakonojo, about 16 miles west of the crater, were delayed by a few hours.
School-bound children were advised to wear masks as a precaution. Farmers woke up to find their fields coated with debris.
In the town of Takahara, located about seven miles east of Kirishima, General Affairs Manager Yuji Nakashima said a small evacuation center had been set up overnight for more than a dozen residents concerned about the debris.
"People told us their windows were rattling and they heard roaring sounds coming from the mountain," Nakashima said.
While frequent activity has been reported at Kirishima, this is the largest eruption recorded there since 1959.
Copyright 2011 ABC News Radio