A magnitude 4.9 earthquake jolted Sarangani province at 3:28 a.m. on Tuesday, Nov. 21, said the Philippine Institute of Volcanology and Seismology (Phivolcs).
Phivolcs said the tremor was an aftershock of the magnitude 6.8 offshore earthquake that struck Davao Occidental on Nov. 17.
The earthquake on Tuesday, which occurred at a depth of 57 kilometers (km), had its epicenter 28 km southwest of Glan, Sarangani.
Phivolcs said the quake was “moderately strong” (Intensity IV) in General Santos City, while it was “weak” (Intensity III) in Tupi, South Cotabato and in Maasim, Sarangani.
Its instruments also recorded the earthquake at Intensity IV in Alabel, Sarangani; City of General Santos; and T'Boli, South Cotabato; Intensity III in Pikit, Cotabato; Maasim, Kiamba, Malungon, Maitum, Malapatan, and Glan, Sarangani; and Suralla, Polomolok, and Tupi, South Cotabato; Intensity II (slightly felt) in Lake Sebu and Tampakan, South Cotabato; and Intensity I (scarcely perceptible) in Bagumbayan, Sultan Kudarat.
Phivolcs said the earthquake was tectonic, which means it was caused by the movement of an active fault near the area.
Meanwhile, as of 8 a.m. of Nov. 21, Phivolcs had recorded 112 aftershocks with magnitudes ranging from 1.4 to 4.9 from the magnitude-6.8 quake in Sarangani on Nov. 17.
Of the recorded aftershocks, 69 have been plotted, while six tremors were felt, said Phivolcs.