The Philippine Institute of Volcanology and Seismology (Phivolcs) explained Wednesday that the strong shaking felt in Kalamansig and other parts of Sultan Kudarat was part of the “earthquake swarm,” which the agency has been closely monitoring since January 19, 2026.
The province was struck by a series of tectonic tremors throughout the day, with the strongest one recorded at magnitude-5.9 at 2:46 p.m. This particular earthquake was located 40 kilometers southwest of Kalamansig and felt at Intensity 5.
Latest data from the state seismic agency showed it has documented a total of 1,646 quakes ranging from magnitudes 1.1 to 5.9 as of 04:00 p.m. on January 28, 2026. At least 507 of these tremors were plotted and 63 were felt.
Phivolcs earlier registered a magnitude-5.4 tremor about 42 kilometers in the same epicenter at 1:05 a.m. Aftershocks soon followed including two non-consecutive magnitude-5.5 quakes that struck about four minutes apart on Wednesday afternoon.
“The series of quakes is not the aftershocks of the first one. We call this event an earthquake swarm,” Winchelle Ian Sevilla, chief of the Seismological Observation and Earthquake Prediction Division, told the Manila Standard. “Usually, the swarm will take days to last,” he pointed out.
Sevilla said the quakes will continue to “go on” on the offshore Celebes Sea. “In this case, the nearest fault to Celebes Sea is the Cotabato Trench,” he noted.
He, however, clarified that residents near the archipelago still felt ground shaking. “To immediately measure the shaking at each location, Phivolcs is using sensors to determine the quake’s intensity,” Sevilla said.
“The results of our sensors are at once transmitted to Phivolcs office in Quezon City. But our field personnel will still have to interview people for another recording of the quakes’ strength or intensity, or damages,” he added.
In light of the frequent seismic activities, Sultan Kudarat Governor Datu Pax Ali Mangudadatu signed an executive order suspending classes and work in public offices as a matter of precaution from Wednesday until further notice.
“The Provincial Government assures the public that the situation is being closely monitored and managed with the highest level of readiness. All concerned offices are on heightened alert to safeguard the safety and welfare of our communities,” Gov. Mangudadatu said in a public advisory.
“This temporary suspension is necessary to allow authorities ample time to conduct structural integrity assessments, continuous monitoring, and other preparedness and safety measures, while enabling residents to take appropriate precautions against possible aftershocks,” he added.
Phivolcs noted that the areas affected by the earthquake swarm are near the epicenter of the 1976 Moro Gulf earthquake, a magnitude 8.0 event that triggered a destructive tsunami in Mindanao.
The agency continues to warn the public of possible aftershocks and has advised residents to remain vigilant and rely on official updates from authorities.
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