MANILA—A series of four shallow earthquakes struck Luzon and Mindanao before dawn on Friday, the Philippine Institute of Volcanology and Seismology said.

At 12:37 a.m., a 4.6 tremor hit 228 kilometers southeast of General Santos City. It occurred at a shallow depth of 32 kilometers.

About two hours later at 2:26 a.m., Davao del Sur was jolted by a 4.3 quake with epicenter traced 84 kilometers southeast of Sta Cruz. It struck at a shallow depth of one kilometer.

After four minutes, a weak 3.6 quake hit inland some six kilometers northwest of Viga, Catanduanes.

At 6:01 a.m., another shallow earthquake measuring 4.2 magnitude on the Richter scale hit with its epicenter traced 11 kilometers southeast of Sta Cruz, Zambales.

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