Northern Luzon at risk of more quakes

MANILA, Philippines — The series of earthquakes that rocked northwestern Luzon last month highlighted “the region’s risk to geologic hazards,” with the Philippine Institute of Volcanology and Seismology (Phivolcs) urging the public to remain vigilant.

On Dec. 4, a magnitude 5.7 earthquake struck Ilocos Norte, followed by a quake sequence that began offshore of Ilocos Sur on Dec. 17, the strongest of which was a magnitude 5 earthquake on Dec. 19.

READ: Ilocos Norte hit by magnitude 5.6 quake

On Dec. 27, a magnitude 5.6 earthquake struck Ilocos Norte. A reported intensity of Intensity 5, or a “strong” shaking based on Phivolcs’ Earthquake Intensity Scale, was also felt in some towns in the province, Ilocos Sur and Cagayan.

Seismic activities

Phivolcs said the quakes “underscore the ongoing tectonic and seismic activities along the Manila Trench,” an extensively studied subduction zone west of Luzon tagged as the cause of powerful quakes along the western Luzon seaboard, from Mindoro island to just off Taiwan island in the north.

But Phivolcs noted that further studies were needed to understand the “tectonic processes driving these events.”

Just before Christmas, it said the earthquake swarm traced to the Manila Trench last month raised the possibility of a strong (magnitude 8.4) earthquake that may cause a disastrous tsunami like the one in Aceh, Indonesia, in 2004.

For now, Phivolcs said it would keep monitoring the earthquake activity and advised the public to “duck, cover and hold” should a strong shaking occur.

(2025/01/02-05:32)