Manila | Two powerful offshore earthquakes struck the same region in the southern Philippines hours apart on Friday.

The first one, a 7.4 magnitude quake in the morning, killed at least five people, set off landslides, damaged hospitals and schools and prompted evacuations of coastal areas nearby because of a tsunami warning, which was later lifted.

The second one had a preliminary 6.9 magnitude. Philippine Institute of Seismology and Volcanology chief Teresito Bacolcol said that Friday night's earthquake that jolted Manay town in Davao Oriental province was caused by movement in the same fault line, the Philippine Trench, at a depth of 10 kilometres (6 miles).

It wasn't immediately clear if it was a separate earthquake or an aftershock of the 7.4 magnitude quake.

President Ferdinand Marcos Jr., facing his latest natural disaster after a recent deadly quake and back-to-back storms, said the potential damage was being assessed, and rescue teams and relief operations were being prepared and would be deployed when it was safe to do so.

The first quake was centred at sea about 43 kilometres (27 miles) east of Manay town in Davao Oriental province and was caused by movement in the Philippine Trench at a depth of 23 kilometres (14 miles).

At least five people were killed, including two patients who died of heart attacks at a hospital during the first earthquake and a resident who was hit by debris in Mati city in Davao Oriental, Ednar Dayanghirang, regional director of the government's Office of Civil Defence, told The Associated Press by telephone.

Two villagers died and several others were rescued with injuries by army troops and civilian volunteers in a landslide set off by the first quake in a remote gold-mining village in Pantukan town in Davao de Oro province near Davao Oriental, Dayanghirang said.

Office of Civil Defence deputy administrator Bernardo Rafaelito Alejandro IV said that several buildings sustained cracks in their walls, including an international airport in Davao City, but it remained operational without any flights being cancelled, Alejandro said.

“I was driving my car when it suddenly swayed, and I saw power lines swaying wildly. People darted out of houses and buildings as the ground shook and electricity came off,” Jun Saavedra, a disaster mitigation officer of Governor Generoso town in Davao Oriental, told The Associated Press by cellphone.

“We've had earthquakes in the past, but this was the strongest,” Saavedra said, adding that the intense ground swaying caused cracks in several buildings, including a high school, where about 50 students were brought to a hospital by ambulance after sustaining bruises, fainting or becoming dizzy because of the first quake.

Governor Generoso is a town about 100 kilometres (62 miles) south of Manay, where school classes in all levels were also suspended.

Children evacuated schools in Davao City, which has about 5.4 million people and is the biggest city near the epicentre, about 250 kilometres (155 miles) west of Davao Oriental province.

The Pacific Tsunami Warning Centre in Honolulu said that small waves were detected on the coasts of the Philippines and Indonesia before the threat passed about two hours after the first quake. It said that small sea fluctuations may continue.

A tsunami warning that set off evacuations in six coastal provinces near Davao Oriental was later lifted without any major waves being detected, chief government seismologist Teresito Bacolcol said.

Indonesia's Meteorology, Climatology and Geophysics Agency said that small tsunami waves were detected in North Sulawesi province with heights ranging from 3.5 to 17 centimetres (1.3 to 6.7 inches) in Melonguane, Beo, Essang and Ganalo in the Talaud Islands districts.

The Philippines is still recovering from a Sept. 30 earthquake with a 6.9 magnitude that left at least 74 people dead and displaced thousands of people in the central province of Cebu, particularly in Bogo city and outlying towns.

The archipelago is also lashed by about 20 typhoons and storms each year, making disaster response a major task of the government and volunteer groups.

Also, on Friday, an earthquake with a preliminary magnitude of 6.0 struck off the coast of Papua New Guinea. The US Geological Survey said that it was centred in the Bismarck Sea 414 kilometres (257 miles) northeast of Lae, the South Pacific island nation's second-most populous city.

Lae police official Mary Jane Huafilong said that no damage was reported.