At 7:37 in the morning of Monday, June 8, 2026, a powerful magnitude 7.8 earthquake rattled offshore Sarangani, sending shockwaves across southern Mindanao and prompting urgent tsunami warnings along multiple coastal provinces. The epicenter was pinpointed approximately 32 kilometers west of Maasim, Sarangani, with the quake originating at a depth of roughly 33 kilometers beneath the seabed.
Cotabato Trench Identified as Source
The Department of Science and Technology's Philippine Institute of Volcanology and Seismology (DOST-PHIVOLCS) determined that the earthquake is tectonic in nature, attributed to subduction activity along the Cotabato Trench. This conclusion was reached by analyzing the quake's epicentral location, focal mechanism, and the distribution of subsequent aftershocks, the agency explained in its official bulletin.
Over 130 Aftershocks Recorded Within Hours
Within just a few hours of the main event, the DOST-PHIVOLCS Philippine Seismic Network (PSN) had already logged a total of 138 aftershocks by 11:00 AM Philippine Standard Time on the same day. Magnitudes of these aftershocks ranged from a low of M1.3 to a significant M6.7. DOST-PHIVOLCS warned that aftershock activity is expected to continue over the coming days and possibly weeks, and that some of these may be strong enough to be felt in surrounding areas.
Intensity VII Felt in General Santos City
Using the PHIVOLCS Earthquake Intensity Scale (PEIS), the strongest ground shaking was recorded at PEIS VII — classified as Destructive — in General Santos City. Ground movement was felt across a wide area, reaching as far north as Abuyog and Dulag in Leyte, though at a much lower PEIS II (Slightly Felt) intensity level, according to DOST-PHIVOLCS data.
Tsunami Waves Wash Ashore Along Southern Coastlines
The 7.8-magnitude event triggered a tsunami, with wave heights of approximately one meter recorded along the shorelines of Kiamba and Maasim in Sarangani, as well as Kalamansig in Sultan Kudarat. This was based on readings from DOST-PHIVOLCS Sea Level Monitoring Stations. Smaller tsunami waves of less than one meter were additionally measured in Mati City and Zamboanga City.
In response, DOST-PHIVOLCS issued a Tsunami Warning for a destructive tsunami affecting the coastal zones of Sarangani, Davao Occidental, Tawi-Tawi, Sulu, Basilan, Zamboanga del Sur, Zamboanga Sibugay, Sultan Kudarat, and South Cotabato.
Coastal residents are reminded by DOST-PHIVOLCS to watch for three natural warning signs of a local tsunami: intense ground shaking (the "shake"), a sudden and unusual rise or drop in sea level (the "drop"), and a loud roaring sound from the direction of the sea (the "roar"). Upon observing any of these signs, immediate evacuation to higher ground is strongly advised without waiting for an official warning.
Other Geological Hazards to Watch For
Beyond the tsunami threat, DOST-PHIVOLCS cautioned that the powerful quake may have triggered landslides, rockfalls, and other mass movement events in mountainous and hilly terrain. Liquefaction is also a concern in low-lying, sandy areas near bodies of water, with possible signs including ground subsidence, fissures, sand boils, and lateral spreading of the soil.
River channels and coastal zones face additional risks from a combination of liquefaction-related ground sinking and changes in sea level, which could result in localized flooding. In areas underlain by limestone, sinkholes may develop. The agency further advised that slopes in affected areas be inspected for newly formed tension cracks, which can heighten landslide risk during heavy rainfall or future aftershocks.
No Volcanic Threat Despite Proximity to Active Craters
DOST-PHIVOLCS clarified that the Mw 7.8 earthquake is purely tectonic in origin and is not associated with any volcanic activity. The closest active volcanoes to Sarangani are Matutum and Parker Volcanoes. As a precautionary measure and consistent with standard monitoring protocols, DOST-PHIVOLCS said it will continue closely observing both volcanoes for any changes that might be linked to the seismic event.
Safety Measures and Public Advisories
Authorities are urging the public to remain alert for additional aftershocks. During any strongly felt shaking, DOST-PHIVOLCS recommends following the "Drop, Cover, and Hold" procedure — dropping to the ground, taking cover beneath a sturdy object, and holding on until the shaking stops.
Heavy furniture and appliances should be fastened securely to walls to prevent them from toppling during subsequent tremors. Structures that appear to have sustained damage must not be re-entered until cleared by licensed structural engineers. Residents are encouraged to contact their local Municipal or City Engineering Office to arrange for building inspections.
Any observed landslides or ground tension cracks should be reported promptly to the appropriate local Disaster Risk Reduction and Management Offices (DRRMOs). The public is also urged to rely only on official updates from DOST-PHIVOLCS and other authorized government agencies, and to avoid spreading unverified information or rumors on social media.
Quick Response Team to Be Deployed
DOST-PHIVOLCS announced that it will dispatch a Quick Response Team (QRT) to Sarangani Province and nearby areas to carry out on-the-ground geologic impact assessments and to conduct information dissemination campaigns for affected communities.
For the latest updates, the public may visit the official website at www.phivolcs.dost.gov.ph or follow PHIVOLCS on Facebook and on X (formerly Twitter) at @phivolcs_dost. Earthquake observation hotlines include: DOST-PHIVOLCS Main Office in Quezon City at (02) 8929-9254 and (02) 8426-1468 to 79; DOST-PHIVOLCS PMCMCET at (082) 293-0008; and the DOST-PHIVOLCS General Santos Seismic Station at (083) 877-7091.
Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS), DOST-PHIVOLCS Primer on the 08 June 2026 Magnitude (Mw) 7.8 Offshore Sarangani Earthquake, Update as of 08 June 2026, 12:00 PM.