A powerful 7.8-magnitude earthquake off the southern Philippines triggered tsunami warnings across several Asia-Pacific nations on Monday, prompting evacuations, emergency alerts and fears of dangerous waves reaching coastlines thousands of kilometres from the epicentre.

The offshore quake struck at a depth of 35 kilometres (22 miles) about 24 kilometres west of Sarangani province on Mindanao island, according to the United States Geological Survey (USGS). While authorities rushed to assess the tsunami threat, rescuers in the Philippines were also responding to collapsed buildings and casualties caused by the strong tremor.

The Pacific Tsunami Warning Center said tsunami waves were possible within hours along the coasts of the Philippines, Indonesia, Palau, Taiwan and Papua New Guinea, triggering heightened monitoring across the region.

Japan's meteorological authorities issued tsunami advisories for broad stretches of the country's Pacific coastline, warning that waves of up to one metre could reach several areas. Indonesia also ordered evacuations in vulnerable northern coastal communities following the earthquake.

As regional authorities focused on the potential tsunami impact, scenes of destruction emerged from southern Philippines.

Videos shared on social media showed a shopping centre housing a Jollibee fast-food outlet collapsing into a pile of rubble in General Santos City. Another video appeared to show a building on a local school campus crumpling during the quake.

General Santos City police said multiple structures were damaged or destroyed by the earthquake.

"A number of buildings collapsed," Master Sergeant Robert Dagon told AFP, adding that homes were among the affected structures.

Police confirmed at least one death and four injuries, though authorities warned the toll could rise as emergency teams continue rescue and assessment operations.

In nearby Davao City, disaster management officials said they were closely monitoring developments and would provide updates as more information became available.

The earthquake's offshore location heightened concerns over tsunami generation, with authorities urging residents in coastal areas to remain alert and follow evacuation instructions where issued. Emergency agencies warned people to stay away from beaches, harbours and low-lying coastal zones until the threat had passed.

The Philippines is one of the world's most disaster-prone countries due to its position on the Pacific Ring of Fire, a vast belt of seismic and volcanic activity that stretches around the Pacific Ocean.

Major earthquakes frequently strike the archipelago. Eastern Mindanao was hit by magnitude-7.4 and magnitude-6.7 earthquakes in October last year that killed at least eight people. Those quakes followed a magnitude-6.9 earthquake that left 76 people dead and damaged or destroyed about 72,000 homes in the central Philippines, according to government figures.

With AFP inputs