MANILA, Dec. 29 (Xinhua) -- A powerful 7.2-magnitude earthquake struck off the Davao Oriental province in the southern Philippine island of Mindanao on Saturday and an early tsunami alert has been lifted, the Philippine Institute of Volcanology and Seismology (Phivolcs) said.

The country's seismology agency initially said that the quake, which occurred off the island of Mindanao, was 7.1 magnitude.

In a revised bulletin, the Phivolcs said the 7.2-magnitude tremor, which struck at 11:39 a.m. local time (0339 GMT), hit at a depth of 54 km, 170 km southeast of Governor Generoso, a town in Davao Oriental.

The tremor, which was of tectonic in origin, was also felt in many parts of Mindanao including Sarangani, Koronadal City, General Santos City, Davao City, and Zamboanga City.

According to the Phivolcs, nearly 10 aftershocks have occurred so far with the highest magnitude of 3.9.

Davao city resident Frinston Lim told Xinhua that people in the largest city in Mindanao felt the major 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 Phivolcs issued a tsunami warning shortly after the strong quake, warning the residents of 11 southern Philippine provinces to stay away from the coastline and to move further inland between 12 p.m. to 2 p.m. local time to avoid the possible tsunami waves.

In an updated statement released on 3 p.m. local time, the institute lifted the tsunami warning, saying only minor waves associated with this earthquake were recorded with a maximum height of 8 cm.

"The last recorded wave occurred at 1:10 p.m. local time for this station. Records show that wave heights have returned to the normal tide level," the institute added.

However, the Phivolcs still advised the local residents in the southern Philippines to stay away from the coastal area.

No reports have been released by the Philippine government yet on the injuries and damages caused by the earthquake.

Philippine Presidential Spokesperson Salvador Panelo said the central government already urged the local government units in Mindanao to closely monitor their respective areas of jurisdiction and take precautionary measures, particularly those in the coastal areas.

"We ask everyone to be alert and cooperate as we pray for the safety of all," he added.

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.