An earthquake measuring magnitude 5.5 on the Richter scale rocked Isabela province on Thursday morning, May 4, said the Philippine Institute of Volcanology and Seismology (Phivolcs).
Phivolcs said the quake, which was initially measured as a 5.8-magnitude tremor, occurred at 8:49 a.m. 29 kilometers northeast of Maconacon, Isabela.
Epicenter of the 5.5-magnitude earthquake that occurred in Isabela province on May 4, 2023 (Phivolcs)
The tremor was felt at Intensity V (strong) in Enrile, Peñablanca and Tuguegarao City in Cagayan province; Intensity IV (moderately strong) in Balbalan, Pinukpuk and Tabuk City in Kalinga, Batac City in Ilocos Norte, and Maconacon Isabela; Intensity III (weak) in Marcos and San Nicolas in Ilocos Norte; and Intensity II (slightly felt) in Pasuquin, Bacarra and Laoag City in Ilocos Norte and Saguday in Quirino.
Phivolcs’ instruments also recorded the quake at Intensity IV in Gonzaga, Cagayan; Intensity III in Ilagan, Isabela; Intensity II in Casiguran in Aurora, Pasuquin, Laoag City and Batac in Ilocos Norte, Vigan City in Ilocos Sur, Santiago City in Isabela, Tabuk in Kalinga, and Madella in Quirino; and Intensity I in Bangued in Abra, Dipaculao and Baler in Aurora, Narvacan in Ilocos Sur, and Bayombong in Nueva Vizcaya.
It said the earthquake was tectonic, which means it was caused by the movement of an active fault near the area.
Phivolcs advised the public to stay vigilant as aftershocks may occur.