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, triggering a tsunami warning, the Philippine Institute of Volcanology and Seismology (Phivolcs) said.

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

The U.S. Geological Survey measured the quake at 7.0 magnitude.

The Phivolcs later issued a tsunami warning as a result of the strong earthquake.

"Minor sea level disturbances such as strong currents and rapid rise and fall of seawaters are expected," the institute said, warning the people "to be on alert for unusual waves."

Coastal areas in southern provinces of Mindanao are expected to experience waves of less than one meter above the normal tide levels, Phivolcs added.

According to the Phivolcs, the first tsunami waves will arrive between 12 p.m. to 2 p.m. local time and the institute also advised residents of 11 southern Philippine provinces to stay away from the coastline and move further inland.

Davao city resident Frinston Lim told Xinhua that people in the largest city in Mindanao felt the tremor strongly.

"Workers rushed out of their offices and car horns sounded off as the ground began shaking, lasting about 15 seconds," Lim said.

The institute said the tremor, which was tectonic in origin, is not expected to cause damage but aftershocks may be expected.

Moderate to large quakes are not rare in the Philippines, an archipelago that sits on the so-called "Pacific Ring of Fire," a seismically active region due to colliding continental plates.

No damages have been reported by the Philippine government yet.