The Philippine Institute of Volcanology and Seismology (Phivolcs) said a moderately strong earthquake measuring 5.8-magnitude on the Richter scale jolted Batangas on Friday evening, Aug. 13.
Phivolcs said it was an aftershock of the 6.6-magnitude earthquake last July 24.
The origin of the 5.8-magnitude quake was traced 18 kilometers (km) southwest of Calatagan, Batangas at around 11:08 p.m. It was initially measured as a 5.7-magnitude earthquake.
Phivolcs said it was "moderately strong" at Intensity IV in Calatagan, Batangas; Puerto Galera and Calapan City, Oriental Mindoro; Lipa City, Lemery and Taal, Batangas; Biñan, Laguna; and Looc and Lubang, Occidental Mindoro.
Moreover, it was "weak" at Intensity III in Pasig City, Parañaque City; Manila City; Quezon City; Caloocan City; Mandaluyong City; Valenzuela City; Abra de Ilog, Oriental Mindoro; Obando, Bulacan; Batangas City; and Tanza, Cavite.
It was recorded as a "slight shaking" at Intensity II in Meycauayan City and Malolos City, Bulacan; Makati City; Pasay City; Pateros; and San Jose, San Pascual, Bauan, Agoncillo, San Luis and Talisay, while it was "scarcely perceptible" at Intensity I in Malabon City.
Phivolcs said aftershocks and damage to structures are less likely to occur.
The 6.6-magnitude mainshock that occurred on July 24 was caused by the movement along the Manila Trench--an earthquake generator located offshore west of Luzon Island, roughly parallel to the Philippine archipelago in the north but veers very close to land at the southern tip of Occidental Mindoro.