Albay province, Philippines - Mt Mayon - famous for its majestic, near-perfect cone shape - is among the most active volcanoes in the Philippines, having erupted at least 50 times in the last 500 years.

In 1841, a blast buried an entire town and killed at least 1,200 people.

The volcano has been spewing fresh lava and ash for almost two weeks.

More than 74,000 people have been evacuated to emergency shelters as authorities warn of a potentially hazardous eruption that could take place in just days.

The alert remains just one notch below the highest level, which is 5, after five more episodes of "intense but sporadic lava fountaining" from the summit crater over a 19-hour period from Tuesday morning, state volcanologists said.

Schools were shut in 17 cities and municipalities in Albay and nearby Camarines Sur province, which was also affected by ashfall. Some 56 flights were cancelled.

Lava fountains 500-600 metres high lasted from seven minutes to more than an hour and generated ash plumes 3-5km above the crater, the Philippine Institute of Volcanology and Seismology (Phivolcs) said.