Thousands of people were forced to evacuate their homes around Taal, one of the world's smallest active volcanoes, which spewed ash for a second day from its crater in the middle of a lake about 70 km south of central Manila.
Police listed another nine to be missing, potentially bringing the death toll to 15.
Italy's National Institute of Geophysics and Volcanology (INGV) said there were two huge explosions on the southcentral side of the volcano's crater at around 1446 GMT on Wednesday.
Authorities have warned that the crater of Anak Krakatau, or child of Krakatau, remains fragile, raising fears of another collapse and tsunami, and have urged residents to stay away from the coast.
The quake was the strongest in the region after Mount Etna erupted, spewing ash and forcing the temporary closure of Sicilian airspace. A series of tremors followed, but the latest one was the strongest.
An eruption in June killed 194 people and left at least 234 missing, although organisations supporting the communities have insisted there are thousands of missing persons.
The Ugandan Red Cross says the death toll could jump when rescue reams access all the affected areas in the foothills of Mountain Elgon in Bududa district.
Adding to Sulawesi's woes, the Soputan volcano in the north of the island erupted early on Wednesday but there were no reports of any casualties or damage.
Mount Mayon, a volcano in Albay province in the coconut-growing central Bicol region, has been erupting since Saturday and the number of people fleeing their homes had more than doubled on Tuesday to about 34,000.
Hundreds of thousands of tourists flock to the Italian island to see Mt Etna's craters, which is Europe's most active and highest volcano.
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