John De Asis, a rescuer in the nearby town of La Castellana, said that ash had begun to descend on local neighbourhoods.
“Tonight, we heard a sudden, loud boom, then after a few minutes, people started reporting that there was ashfall in their areas,” he said, noting that rescue personnel were handing out face masks
Bacolcol said it was possible that “gas pressure had built up at the vent” of the volcano. He said recent low sulphur dioxide emissions suggested a potential blockage that would have caused pressure to build.
The volcano, which straddles Negros Oriental and Occidental provinces, currently has a 4km exclusion zone in place.
The Philippines is on the seismically active region of the Pacific known as the “Ring of Fire”, where more than half the world’s volcanoes are located.
The most powerful volcanic explosion in the Philippines in recent years was the 1991 eruption of Pinatubo, about 100km from Manila, which killed more than 800 people.
- Agence France-Presse