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

The institute said the quake struck off Pondaguitan at 11:39 a.m. local time at a depth of 49 km.

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

The U.S. National Weather Service's Pacific Tsunami Warning System released a hazardous wave alert for all coasts within 300 km of the quake.