A 7.8-magnitude earthquake struck off the southern coast of the Philippines on Monday, the United States Geological Survey said, prompting a regional warning centre to issue a tsunami alert.

The offshore quake hit at a depth of 35 kilometres about 24 kilometres west of Mindanao's Sarangani province, USGS said.

The quake has killed at least one person and injured four others while collapsing "a number of buildings", police told AFP.

"Many buildings were affected, but I cannot enumerate them now because we are busy with ongoing rescues," Master Sergeant Robert Dagon of the General Santos City police said.

Videos posted to Facebook showed a shopping centre with a Jollibee fast food restaurant collapsing into rubble in the province's General Santos City, while a building on a local school campus crumpled in another.

"Lord, it has really collapsed! It has really collapsed! The building has really collapsed!" someone can be heard shouting.

The Pacific Tsunami Warning Center said in a notice that tsunami waves were possible "within the next three hours" along the coasts of the Philippines, Indonesia, Palau, Taiwan and Papua New Guinea.

Japanese authorities separately issued a tsunami advisory for swathes of its Pacific coast, projecting waves of up to one metre to hit different regions from 11.30 am local time.

In Mindanao's capital Davao City, a local disaster official said only that authorities were monitoring the situation and would post updates on social media.

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.