A powerful earthquake with a magnitude of 7.2 struck off a southern Philippine province Saturday and prompted a local tsunami warning, but there were no immediate reports of damage or injuries.

Renato Solidum of the Philippine Institute of Volcanology and Seismology said the pre-dawn quake was centered at sea off Sarangani province and struck relatively deep below the seabed, causing much of its disastrous power to dissipate. The quake roused people from sleep, but there were no reports of casualties.

Coastal towns were warned of possible small tsunami waves of less than a meter (3 feet), which did not require villagers to evacuate but nothing untoward has been reported, Solidum said.

The Philippines sits on the Pacific "Ring of Fire," where earthquakes and volcanoes are common. A magnitude-7.7 killed nearly 2,000 people in the northern Philippines in 1990.