BUTUAN CITY (MindaNews / 28 December) – The Philippine Institute of Volcanology and Seismology (Phivolcs) has identified the Philippine Fault-Agusan Marsh segment as the likely source of the earthquake that struck Talacogon, Agusan del Sur on December 26.
In a briefer published on Friday, Phivolcs said the magnitude 5.3 earthquake, with a depth of 12 km, that struck Talacogon, showed strike-slip faulting or horizontal motion along the fault, with the Philippine Fault-Agusan Marsh segment identified as the likely source.
The tremor generated aftershocks, including a magnitude 4.6 quake with a depth of 7 km.
“The Philippine Fault-Agusan Marsh segment is part of the larger Philippine Fault system that runs through Agusan del Sur. Earthquakes along this segment can also impact neighboring provinces, highlighting the importance of preparedness across the region,” Phivolcs said.
Based on the updated earthquake bulletin published by Phivolcs, the earthquake was reported to have been felt in a large part of Mindanao.
Intensity V was recorded in Talacogon, while Intensity IV was observed in Bislig City and Hinatuan in Surigao del Sur.
Intensity III was felt in the City of Gingoog, Jasaan, Magsaysay, and Medina in Misamis Oriental; Laak, Mabini, Monkayo, and Nabunturan in Davao de Oro; and Barobo in Surigao del Sur while
Intensity II was reported in Malitbog and Valencia City in Bukidnon; Claveria, Tagoloan, and Villanueva in Misamis Oriental; Cagayan de Oro City; Maco in Davao de Oro; Kabacan and Matalam in Cotabato; and Cagwait in Surigao del Sur.
Phivolcs added that while it is not possible to predict the exact timing and magnitude of future earthquakes, these risks should be approached “with caution and readiness rather than fear.”
Earlier this year, Phivolcs published a study titled Stress Releases and Seismic Gaps: Earthquake Sequences Strike Eastern Mindanao, Philippines, which highlighted that tectonic stress along the Philippine Fault in Mindanao is increasing, possibly influenced by recent earthquakes along the Philippine Trench.
On December 2, 2023, a magnitude 7.4 earthquake struck off Hinatuan, Surigao del Sur, followed by numerous aftershocks, including a magnitude 6.8 event two days later. Phivolcs suggested that these two events ruptured separate sections of the Philippine Trench.
The study also pointed out that historical seismic gaps, particularly in the Esperanza, Agusan Marsh, and Mati segments of the Philippine Fault, raised concerns about the potential for future earthquakes along these fault segments.
“These findings reinforce the importance of disaster preparedness and encourage communities to prioritize proactive safety measures in their daily lives,” the study said.
In Mindanao, the Philippine Fault consists of several segments, including Surigao, Esperanza, Agusan Marsh, West Compostela Valley, Central Compostela Valley, Nabunturan, East Compostela Valley, Caraga River, Mati, and Lianga. (Ivy Marie Mangadlao/MindaNews)
