MANILA -?An offshore earthquake with a preliminary magnitude of 6.4 rocked Cagayan province in the northern Philippines Tuesday night, the Philippine Institute of Volcanology and Seismology said.

The institute said the quake, which occurred at 7:03 p.m. local time, hit at a depth of 10 kilometers, about 26 kilometers northwest of Dalupiri Island in Calayan town.

The institute said the tectonic quake will trigger aftershocks but will not cause damage.

It said the quake was felt in many areas in the main Luzon island and the central Philippines.

The archipelagic Philippines has frequent seismic activities due to its location along the Pacific "Ring of Fire."