Manila - A Philippine volcano has spewed ash for the second time in less than a week but there were no signs of any imminent violent eruption, the country's chief volcano expert said on Thursday.
Mount Bulusan in Sorsogon province southeast of Manila ejected ash 250m above the 1 565m volcano late on Wednesday, said Renato Solidum, director of the Philippine Institute of Volcanology and Seismology.
The agency asked local officials to keep people away from a 4km hazardous zone around the crater, he said. He said aircraft should not fly close to the mountain to avoid any sudden explosions and ash clouds.
Solidum said 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. The ash explosion lasted about 3-1/2 minutes, shorter than the 5-minute explosion recorded May 1.
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A large explosion in February 2011 that shot an ash plume about 2km into the sky prompted about 1 200 villagers to flee to shelters.
Bulusan is one 23 volcanoes considered active by the volcanology agency, but it has not had a violent eruption since in 1918.
The country is in the Pacific "Ring of Fire", where volcanic activity and earthquakes are common. In June 1991, Mount Pinatubo in the northern Philippines exploded in one of the biggest eruptions in the 20th century.