The Philippines’ most active volcano is gently spewing lava down its slopes, prompting officials to warn tens of thousands of villagers to be prepared to flee from their homes if the gentle eruption turns into a violent and life-threatening explosion. More than 13,000 people have left the mostly poor farming communities near Mayon Volcano’s crater in mandatory evacuations. But an unspecified number of residents remain in the permanent danger zone. The director of the Philippine Institute of Volcanology and Seismology said Monday the high-risk zone may be expanded should the eruption turn violent. Teresito Bacolcol told The Associated Press: “What we are seeing now is an effusive eruption. We are looking at this on a day-to-day basis.”