A Philippine volcano has spewed ash but volcanologists say there are no signs of any eminent violent eruption.

Renato Solidum, chief of the Philippine Institute of Volcanology and Seismology, says Mount Bulusan in Sorsogon province southeast of Manila ejected ash 250 meters (825 feet) above the 1,565-meter (5165-foot) volcano late Wednesday.

He said Thursday that the agency has reminded local officials to keep people away from a 4-kilometer (2.5-mile) hazardous zone around the crater. He said aircraft also should not fly close to the mountain to avoid any sudden explosions and ash clouds.

Solidum says the explosion was due to ground water coming into contact with hot rocks and not rising magma. He says such "phreatic" explosions are typical of Bulusan.