The Philippine Institute of Volcanology and Seismology (Phivolcs) has upgraded the magnitude of the earthquake that jolted Zambales province on Monday evening, March 15, to 4.8.
Initially measured at 4.3-magnitude, Phivolcs recorded the light earthquake around 7:20 p.m. and traced its epicenter at 23 kilometers southwest of Iba, Zambales.
Residents felt the earthquake at Intensity IV as a "moderately strong" shaking in Iba, Botolan, Cabangan and San Felipe in Zambales.
It was felt as a "weak" earthquake at Intensity III in Olongapo City, San Antonio, San Marcelino, San Narciso, Palauig and Subic in Zambales; and Floridablanca, Pampanga.
Meanwhile, it was a "slight shaking" at Intensity II in Candelaria, Masinloc and Santa Cruz, Zambales; Mabalacat City, Pampanga; Makati City; Malabon City; Manila City; Quezon City; and Villasis, Pangasinan.
Phivolcs’ instruments also recorded the quake at Intensity II in Guagua, Pampanga and Intensity I in Calumpit, Bulacan; Marikina City; Quezon City; San Jose City, Nueva Ecija; and Dagupan City, Pangasinan.
It said the quake was tectonic in origin, which means the tremor was caused by the movement of an active fault in the area. Moreover, it was shallow at a depth of 26 kilometers thus the strong shaking. Phivolcs said aftershocks are unlikely to occur.