The Philippine Institute of Volcanology and Seismology (Phivolcs) said that a moderately strong earthquake, measuring magnitude 5.7 on the Richter scale, struck off the coast of Northern Samar on Monday, Aug. 19.
Phivolcs recorded the tremor at 11:39 a.m. and located its epicenter 54 kilometers northwest of Pambujan, Northern Samar.
It was initially measured as a magnitude 6 earthquake.
The quake was felt at Intensity V (strong) in Bobon, Catarman, Laoang, Lavezares, Palapag, Rosario, and San Roque in Northern Samar and Intensity IV (moderately strong) in Pilar and Sorsogon City, Sorsogon.
Meanwhile, it was felt at Intensity III (weak) in Legazpi City and Tabaco City in, Albay; Virac in Catanduanes; Masbate City in Masbate; Bulusan and Irosin in Sorsogon; and Burauen and Javier in Leyte.
It was also slightly felt at Intensity II in Calubian, Hilongos, Leyte, and Mahaplag in Leyte and in Hinunangan and Sogod in Southern Leyte.
Phivolcs instruments also recorded the quake with varying intensities across several areas in Eastern Visayas and Bicol Region.
Intensity V was recorded in Rosario and San Roque, Northern Samar.
Intensity IV was observed in Bulusan and Sorsogon City in Sorsogon; Can-Avid in Eastern Samar; Abuyog in Leyte; and Gandara in Samar.
Intensity III was reported in Legazpi City and Tabaco City in Albay; Masbate City and Uson in Masbate; Pilar in Sorsogon; Sulat in Eastern Samar; and Alangalang, Carigara, Dulag, and Javier in Leyte.
Intensity II was recorded in Tinambac, Camarines Sur; Aroroy, Batuan, Cataingan, Esperanza, and Milagros in Masbate; Burauen, Calubian, Hilongos, Kananga, Mahaplag, and Palo in Leyte; and Hinunangan and Sogod in Southern Leyte.
Intensity I was observed in Caramoan and Pasacao in Camarines Sur; Claveria in Masbate; Roxas City in Capiz; Cebu City; and Albuera in Leyte.
The earthquake was tectonic in origin, caused by the movement of an active fault near the area.
While no immediate damage was anticipated, Phivolcs warned that aftershocks could occur.