SEISMOLOGISTS at the Philippine Institute of Volcanology and Seismology (Phivolcs) assured the public on Wednesday, January 28, 2026, that no tsunami warning has been issued following the series of earthquakes that have rattled parts of Sultan Kudarat over the past two weeks.
Phivolcs said the strongest quake recorded during the swarm, a magnitude 5.9 earthquake that struck southern Philippines, was not powerful enough to trigger a tsunami.
Phivolcs Executive Director Teresito Bacolcol said the agency continues to closely monitor the seismic activity, particularly in the vicinity of Kalamansig, Sultan Kudarat, where a large number of tremors have been recorded.
From January 16 to January 28, Phivolcs logged a total of 1,646 earthquakes in the area, classifying the activity as an earthquake swarm rather than isolated seismic events.
Bacolcol said five of the earthquakes recorded on Wednesday reached intensities higher than intensity V, which were felt strongly by residents in nearby communities.
According to him, the swarm was caused by the slow and gradual release of accumulated stress along the Cotabato Trench, a major tectonic feature off the coast of Mindanao. This gradual movement, Bacolcol explained, eventually triggered the magnitude 5.9 earthquake but does not necessarily indicate an imminent major quake.
“At present, it is difficult to say whether this will lead to a major movement, and we do not have the technology to predict if a larger earthquake will occur next,” Bacolcol said over a national radio interview.
Despite the absence of a tsunami threat, he urged residents in affected areas to remain vigilant, particularly as aftershocks may continue in the coming days.
Bacolcol advised local government units and communities to review their preparedness measures and be ready for possible evacuations should conditions worsen.
Classes, work suspended in affected towns
As a precautionary measure, local authorities in Sultan Kudarat have ordered the suspension of classes and work in areas most affected by the seismic activity.
On January 28, classes and work in the towns of Kalamansig and Lebak were suspended starting Wednesday, following reports of continued earthquakes and the possibility of aftershocks.
Governor Datu Pax Ali Mangudadatu announced the suspension through a social media post, saying the decision was made to prioritize public safety.
In an advisory, the governor said the suspension covers work and classes at all levels, in both public and private institutions, and will remain in effect until further notice “to ensure the safety of everyone.”
Local disaster risk reduction and management offices have been placed on heightened alert, while authorities continue to assess possible damage to infrastructure and monitor the situation on the ground.
Seismic activity traced to Cotabato Trench
To recall, the agency reiterated that the ongoing seismic activity is linked to the Cotabato Trench, a major offshore tectonic feature west of Mindanao formed by the interaction of tectonic plates. The trench is part of the complex fault system affecting southern Philippines and has historically generated moderate to strong earthquakes, though not all movements result in destructive events.
Bacolcol emphasized that the current earthquake swarm reflects the gradual release of stress along the Cotabato Trench rather than a single, large rupture. While no tsunami threat has been identified and no major quake is currently anticipated, Phivolcs said continued vigilance remains essential as aftershocks may persist. Residents were urged to stay informed through official advisories, inspect structures for damage, and remain prepared for possible evacuations should conditions change. DEF