There were no immediate reports of casualties.
"Strong earthquake here in Taft, Eastern Samar! And it lasted very long too!" Samar congressman, Ben Evardone, told reporters via text message.
"We are in a wait and see situation, some bridges and roads were damaged and people panicked and are now on higher ground," he told local radio later.
"If you are anywhere near the coast I recommend that you head to higher ground," Paul Caruso of the U.S.G.S. told Sky TV by telephone when asked about a threat of a tsunami hitting the coast of the Philippines.
Renato Solidum, head of the Philippine seismology agency, said residents should get to a 10-meter (30-foot) elevation until the tsunami alert was lifted.
Small waves of about 16 centimeters (6 inches) had hit a southern Philippine island, the agency said, and warned that bigger ones could follow.
A radio reporter in Leyte province, near Samar, said people had run out of their homes when the quake struck. "It felt like we were being rocked," he said.
The region has been hit by devastating quakes in the past decade. At least 230,000 people in 13 Indian Ocean countries were killed in a quake and tsunami off Indonesia in 2004.
Last year, an earthquake and tsunami off Japan's northeastern coast killed about 20,000 people and triggered the world's worst nuclear crisis in 25 years after waves battered a nuclear power station.
Intellpuke: This article is a compilation of reporting by NBC News correspondents and various news agencies; you can read it in context here: worldnews.nbcnews.com/_news/2012/08/31/13589664-76-magnitude-earthquake-strikes-off-philippines?lite