The shallow but powerful quake struck the mountainous and lightly populated province of Abra on the main island of Luzon at 8:43 am (0043 GMT), the USGS said.
Shallow earthquakes tend to cause more damage than deeper ones.
In the municipality of Dolores, which felt the full force of the quake, terrified people ran outside their homes and shops, and the local market’s windows were shattered, Police Major Edwin Sergio told AFP.
"The quake was very strong," Sergio said, adding there were small cracks in the police station building.
"Vegetables and fruits sold in the market were also disarranged after tables were toppled."
Ring of Fire
The Philippines is regularly rocked by quakes due to its location on the Pacific "Ring of Fire", an arc of intense seismic activity that stretches from Japan through Southeast Asia and across the Pacific basin.
Wednesday’s quake was the strongest recorded in the Philippines in years.
In October 2013, a magnitude 7.1 earthquake struck Bohol Island in the central Philippines, killing over 200 people and triggering landslides.
In 1990, a magnitude 7.8 earthquake in the northern Philippines created a ground rupture stretching over a hundred kilometres.
The nation’s volcanology and seismology institute regularly holds quake drills, simulating scenarios in the nation’s active fault lines.
During major earthquakes, the agency said people would find it difficult to stand on upper floors, trees could shake strongly, heavy objects and furniture may topple and large church bells may ring.