The Philippines raised the alert on its most active volcano to the second-highest level on Monday and ordered the evacuation of around 20,000 people after three ash explosions signalled a possible eruption within days. Mayon volcano in the central Philippines has been spewing lava and rocks since last month, leaving a bubbling, pyrotechnic trial more than 6 km down its southeastern slope. "We deem it necessary to raise the alert level to four because there were three ash explosions this morning," Philippine volcanology and seismology director Renato Solidum told Reuters. "That would mean that the hazardous eruption is more likely." The military sent trucks to ferry thousands of villagers to evacuation centers outside an 8 km (5 mile) danger zone on the southeast the 2,462-metre-high (8,077 feet) Volccano. Disaster officials have previously said that around 60,000 people in Albay province would be evacuated in the event of a major eruption. Mayon is the most active volcano in the country, having erupted around 50 times over the past four centuries. The most destructive eruption came in February 1841 when lava flows buried a town and killed 1,200 people. The last time Mayon erupted was in 2000-2001.