The Philippines has raised the alert level at its rumbling Mayon volcano to "level 3" after detecting lava flow and indications of activity that could lead to eruptions of magma.
More than 900 families have been evacuated from villages near Mayon, a tourist attraction on Luzon island, because of its near-perfect cone shape, following a "steam-driven eruption" on Saturday.
This comes as a magnitude-5.1 earthquake hit the Philippines, about 64 kilometres west-southwest of Batangas on the island of Luzon, the US Geological Survey says.
The Philippine Institute of Volcanology and Seismology measured the quake at magnitude 5.2 and said no damage was expected, but aftershocks were likely.
The USGS said the tremor occurred at 11:45pm local time on Sunday (4:45am Monday NZ time) and had a depth of 35km.