DAVAO, Philippines (AP) _ An earthquake jolted two southern Philippine provinces for the third time in a week, but there were no reports of damage or injuries, officials said Sunday.

The earthquake on Saturday shook the provinces of Davao and Surigao, the same area affected by a 6.6-magnitude temblor on New Year's Day, the Philippine Institute of Seismology and Volcanology said.

The institute estimated the magnitude of Saturday's quake at 4.7, though seismologists in Hong Kong placed it at 5.6.

Saturday's temblor was centered at sea about 54 miles southeast of Mati in Davao, the institute said. The province is about 600 miles southeast of Manila.

Seismologists said the earthquake was triggered by a movement in the Philippine trench, a fault line running along the country's southeastern Pacific coast.

The Philippine archipelago sits on at least four major faults and lies in the so-called Pacific ``ring of fire'' where earthquakes and volcanic activity are common.