A 6.1-magnitude earthquake struck off the west coast of the main Philippine island of Luzon on Sunday, US seismologists said, but there were no reports of casualties and no tsunami alert was issued.
The US Geological Survey said the quake hit at a depth of 35 kilometres (22 miles) at 6:18 am (2218 GMT Saturday), 182 km northwest of the capital Manila.
The Philippine Institute of Volcanology and Seismology measured the quake at 6.0 magnitude.
The quake was felt in some areas, including Manila, but there were no immediate reports of damage or casualties, said civil defence chief Benito Ramos.
The Philippines sits on the Pacific Ring of Fire -- a belt around the Pacific Ocean dotted by active volcanoes and unstable ocean trenches.
One fault line runs directly under Manila, a metropolis of more than 12 million people, and government seismologists have warned the city is unprepared for a major quake.
In February, a 6.7-magnitude earthquake in the central Philippines triggered landslides that left more than 100 people dead or missing.