MANILA (AP) - The Philippine Institute of Volcanology and Seismology raised the alert level on Mount Bulusan Sunday after detecting increasing signs of activity that could be a precursor to a new bout of explosive eruptions, officials said.
The 1,560-meter Mount Bulusan in Sorsogon province, about 390 kilometers southeast of Manila, has been showing signs of unrest since coming back to life in March 2006 with on-and-off ash and steam explosions.
Since it ejected ash on May 12, the mountain's northeastern slope has swelled slightly and abnormally high numbers of earthquakes have been recorded, prompting authorities on Sunday to raise the public alert level from one to two on a five-step scale, the Philippine Institute of Volcanology and Seismology said in a statement.
The alert upgrade indicates a shift from "low-level volcanic activity" to a "moderate level of volcanic unrest," said Crispulo Diolata, an official at the institute. An alert level of five means a life-threatening eruption is in progress, Diolata said.