THE Department of Science and Technology’s Philippine Institute of Volcanology and Seismology (DOST-Phivolcs) clarified that the magnitude 7.8 earthquake that struck offshore Sarangani on June 8, 2026, is purely tectonic in origin and is not expected to trigger volcanic activity in nearby volcanoes.
In its earthquake primer released on the same day, DOST-Phivolcs said the powerful tremor, which originated 32 kilometers west of Maasim, Sarangani, at a depth of 33 kilometers, was likely caused by subduction-related movement along the Cotabato Trench, one of the country’s major earthquake-generating structures.
The agency emphasized that despite the quake’s strength, there is no indication that it is connected to volcanic unrest.
“No. While the nearest active volcanoes to Sarangani are the Matutum and Parker Volcanoes, the Mw 7.8 earthquake is tectonic in origin. Nevertheless, in line with standard monitoring protocols for moderate to great earthquakes occurring near active volcanoes, the Institute will continue to closely monitor the area for any volcanic activity that may be affected by the event.”
Phivolcs said strong earthquakes occurring near active volcanoes are routinely monitored to determine whether seismic activity could influence volcanic systems. However, based on current observations, no volcanic activity associated with the earthquake has been detected.
The earthquake struck at 7:37 a.m. on June 8 and generated widespread shaking across Mindanao. The highest recorded intensity reached PEIS VII (Destructive) in General Santos City, while weaker tremors were felt as far as Leyte.
Phivolcs said it had recorded 1,055 aftershocks as of 7 a.m. on June 9, following with magnitudes ranging from 1.3 to 6.7.
The agency said 301 of the aftershocks had been located, while 21 were felt in affected communities.
The agency also confirmed that the offshore quake generated tsunami waves along portions of Sarangani and Sultan Kudarat.
Sea level monitoring stations recorded waves of about one meter in Kiamba, Maasim, and Kalamansig, while smaller wave disturbances were observed in Mati City and Zamboanga City. The tsunami warning issued shortly after the earthquake was later lifted after monitoring showed no damaging waves.
Aside from aftershocks, the agency warned communities to remain alert for secondary hazards such as landslides, rockfalls, liquefaction, ground fissures, and coastal inundation, particularly in low-lying and water-saturated areas.
Phivolcs urged the public to avoid damaged structures until cleared by engineers, inspect slopes for cracks that could lead to landslides, and stay vigilant for natural tsunami warning signs such as strong ground shaking, sudden changes in sea level, or unusual roaring sounds from the ocean.
The agency also reminded residents to rely only on official advisories from government authorities and avoid spreading unverified information as response and recovery efforts continue in areas affected by the earthquake. DEF
