The biggest of the quakes, with a magnitude of 7.4, hit about 20 kilometres (12 miles) off Manay town in the Mindanao region just before 10 am (0100 GMT), according to the United States Geological Survey.

An aftershock with a magnitude of 6.7 rocked the same area almost 10 hours later, one of scores that followed the morning quake.

Both came 11 days after a magnitude 6.9 earthquake killed 75 people and injured more than 1,200 in Cebu province in the central Philippines, according to official data.

Three miners tunnelling for gold were killed when a shaft collapsed in the mountains west of Manay during the larger quake, rescue official Kent Simeon of Pantukan town told AFP.

One miner was pulled out alive and several others were injured in the remote hamlet of Gumayan, he said.

"Some tunnels collapsed, but the miners managed to get out," Simeon said.

One person was killed in Mati city, the largest urban centre near the epicentre, when a wall collapsed, while another suffered a fatal heart attack, officials said.

Another person was also crushed by falling debris in Davao city, more than 100 kilometres west of the epicentre, police said.

Philippine authorities issued tsunami warnings shortly after the morning quake, ordering evacuations along the eastern seaboard.

The Pacific Tsunami Warning Center lifted its alert for the Philippines, Palau and Indonesia at around noon.

- 'People screamed and ran' -

Wes Caasi, an official in Tagum city, northwest of Manay, told AFP that a government event at the city hall descended into chaos as panicked attendees fled. "They screamed and ran."

Confirming videos that circulated on social media, Caasi said she saw city workers scrambling down a metal Christmas tree they were decorating when the first quake struck.

Nice Eugenio from Tagum city told AFP the strong aftershock knocked out power in her neighbourhood.

"It lasted only a few seconds, but (it) was very strong. I felt like I was going to faint from nervousness," she said.

A plane that had just landed in Davao city was shaken by the aftershock, which prevented passengers from disembarking immediately, an AFP photographer on board said.

Witnesses and officials said the quakes appeared to have caused only minor damage, while the Philippine seismology office said it had recorded more than 300 aftershocks.

There were no reports of collapsed buildings but "there were landslides and our bridges exhibited cracks", Davao Oriental provincial governor Nelson Dayanghirang told the ABS-CBN network.

"Some buildings were damaged," he said.

More than 200 patients were evacuated from the Manay district hospital, where tents were set up outside to shelter them after the building's foundations cracked, Dayanghirang said.

Dianne Lacorda, a Davao Oriental police officer, told AFP that power and communication lines were down, hampering damage assessments.

Classes were suspended and non-essential workers were sent home, the provincial government said on Facebook.

- 'Shaking was so strong' -

Christine Sierte, a teacher in the town of Compostela near Manay, said the violent shaking started when she was in an online meeting.

"It was very slow at first, then it got stronger.... That's the longest time of my life. We weren't able to walk out of the building immediately because the shaking was so strong," she told AFP.

"The ceilings of some offices fell, but luckily no one was injured," she said.

Earthquakes are a near-daily occurrence in the Philippines, which is situated on the Pacific "Ring of Fire", an arc of intense seismic activity stretching from Japan through Southeast Asia and across the Pacific basin.

An 8.0-magnitude quake off Mindanao island's southwest coast in 1976 unleashed a tsunami that left 8,000 people dead or missing, the Philippines' deadliest natural disaster.