A 4.7-magnitude earthquake jolted Ilocos Sur at around 1:49 p.m., Sunday, July 31, said the Philippine Institute of Volcanology and Seismology (Phivolcs).
It said the tremor was an aftershock of the 7.0-magnitude earthquake that struck Tayum, Abra on July 27.
Phivolcs traced the epicenter of the earthquake on Sunday at 5 kilometers (km) northeast of Cabugao, Ilocos Sur.
It was felt at Intensity V as a “strong” tremor in Dolores, Abra and at Intensity IV as a “moderately strong” quake in Sinait, Ilocos Sur.
Bantay in Ilocos Sur and Batac and Dingras in Ilocos Norte felt the quake at Intensity III (weak), and Intensity II (slightly felt) in Bacarra, Ilocos Norte.
Its instruments also recorded the quake at Intensity IV in Sinait and Vigan City in Ilocos Sur; Intensity III in Laoag City, Ilocos Norte; and Intensity II in Peñablanca, Cagayan and Pasuquin, Ilocos Norte.
Phivolcs said the earthquake was tectonic, which means it was caused by the movement of an active fault near the area.