MANILA—A magnitude 4 earthquake struck off Vigan, Ilocos Sur at 1 a.m. Monday, the Philippine Institute of Volcanology and Seismology said.

There were no immediate reports of damage or injury from the moderate quake that hit 19 kilometers northwest of the northern Philippine city. It had a shallow depth of 28 kilometers.

The Philippines sits on the Pacific “Ring of Fire” where continental plates collide causing frequent seismic an volcanic activity.