Scientists in the Philippines have raised the volcano alert level for Mount Mayon and say an eruption is imminent.
It is now at four out of a possible five, meaning a hazardous eruption "is possible within days".
The BBC reports the level was raised after the number of volcanic earthquakes more than doubled on Sunday.
About 40,000 people have been moved to temporary shelters.
The Philippine Institute of Volcanology and Seismology said 453 volcanic earthquakes were detected in a five-hour span on Sunday, compared to just over 200 on Saturday.
Powerful booms emanating from the volcano, audible up to 12km away.
Mayon's last eruption was in 2006. Located 330km south-east of Manila, it has erupted 48 times since records began. The most violent eruption was in 1814.