MANILA, Dec. 29 (Xinhua) -- A powerful 7.1-magnitude earthquake struck off the Davao Oriental province in the southern Philippine island of Mindanao on Saturday, the Philippine Institute of Volcanology and Seismology (Phivolcs) said.

The institute said the quake hit at 11:39 a.m. local time at a depth of 49 km. The epicenter was located offshore, 162 km southeast of Governor Generoso in Davao Oriental.

The Phivolcs said the tremor, which was tectonic in origin, is not expected to cause damage but major aftershocks maybe expected.

The Philippine government has issued a tsunami warning.

The U.S. Geological Survey measured the quake at 6.9 magnitude.

No damages have been reported by the Philippine government yet.