PRIMER ON THE 30 SEPTEMBER 2025
MAGNITUDE (MW) 6.9 OFFSHORE NORTHERN CEBU EARTHQUAKE
Update as of 1 October 2025
What is happening in Cebu and vicinity?
At 9:59 PM Philippine Standard Time (PST) on 30 September 2025 (Tuesday), a strong earthquake with magnitude (MW) 6.9 rocked Cebu and surrounding provinces. The earthquake has an epicenter located 19 kilometers northeast offshore of Bogo City and estimated depth of 5 kilometers (Figure 1). As of 8:00 AM PST on 1 October 2025, the DOST-PHIVOLCS Philippine Seismic Network (PSN) has recorded a total of 722 aftershocks ranging from M1.4 to M4.8.
Using the PHIVOLCS Earthquake Intensity Scale (PEIS), the highest reported intensity is PEIS VII (Destructive), which was felt in Bogo City, Daanbantayan, Medellin, San Remigio, anTabuelan in Cebu Province (DOST-PHIVOLCS Earthquake Information 4). At PEIS VII, many people could be frightened and may run outdoors. Heavy objects and furniture could overturn or topple. Big church bells may sway and ring. Old or poorly-built structures could likely suffer significant damage. Some well-built structures could be slightly damaged. Some cracks could appear on dikes, fish ponds, road surface, or concrete hollow block walls. Liquefaction, lateral spreading, and landslides could be observed. Trees could be shaken strongly.
Have strong earthquakes affected Cebu and its vicinity in the past?
Yes. At least eight significant earthquakes with magnitudes ranging from M5.0 to M7.2 affected Cebu and nearby provinces between 1885 and 2013 based on historical records and DOST-PHIVOLCS Earthquake Catalog. The recent damaging earthquakes were the MS6.9 event in Negros Oriental on 6 February 2012, and the MS7.2 event in Bohol on 15 October 2013. In both earthquakes, several buildings and infrastructure were damaged in Cebu Province.
Why do earthquakes occur in the vicinity of Cebu?
Cebu and neighboring provinces are situated in one of the seismically active regions in the country. Among the earthquake sources are Bogo Fault, Daanbantayan Lineament, and the Cebu Fault System. There are also local inland and offshore faults, some concealed by recent deposits, capable of generating earthquakes ranging from minor to strong magnitudes.
What can we expect from the current earthquake activity?
We can expect aftershocks in the epicentral area. These aftershocks could persist for several days to weeks, and some may be felt in nearby provinces.
Aside from strong ground shaking, what other earthquake hazards may be expected?
Earthquake-induced landslides, rock falls, and other types of mass movement may occur on sloping terrains, specifically in mountainous or hilly areas. Liquefaction, manifested by subsidence, ground fissures, sand boils, and/or lateral spreads, may affect low-lying, water-saturated, and sandy areas near water bodies. Active river channels and coastal areas may be vulnerable to inundation of seawater due to the combination of liquefaction-induced subsidence and changes in sea level due to high tide. Sinkholes may appear in areas with limestone bedrock. Damage to buildings and infrastructure, falling debris, and landslides could cause casualties. Based on the National Disaster Risk Reduction and Management Council (NDRRMC) Situational Report No. 1, a total of 26 fatalities and 147 injured persons were reported (for validation) as of 8:00 AM, 1 October 2025.
Can this earthquake event trigger a tsunami?
Yes. DOST-PHIVOLCS released, and lifted after three hours, a Tsunami Information of minor sea level disturbance for the coasts of Cebu, Leyte, and Biliran Provinces. Citizen reports of seawater recession in Camotes Island will be further verified by DOST-PHIVOLCS. In case of another strong earthquake in the vicinity, people should be watchful and stay away from beaches and coasts.
Can this earthquake indicate volcanic activity?
No. Although the nearest active volcanoes to Cebu are Biliran and Kanlaon (which is at Alert Level 2), the MW 6.9 earthquake is tectonic in origin. However, as part of DOST-PHIVOLCS’ monitoring procedures for moderate to major earthquakes occurring near active volcanoes, the Institute will continue to monitor any activity that may affect these two volcanoes.
What should be done by the affected communities?
Prepare for aftershocks. In case of another strongly felt earthquake, it is recommended that people protect themselves by doing the “drop, cover, and hold.” In homes and offices, heavy furniture and appliances should be strapped to the walls, and hanging objects securely fastened to avoid causing injuries.
Be cautious of structures visibly weakened or with signs of damage caused by the MW 6.9 Offshore Northern Cebu Earthquake, as these may further be damaged by succeeding earthquakes. It is best to contact the concerned Municipal/City Engineering Office for inspection and advice. Civil engineers from the local government and other organizations are strongly enjoined to inspect buildings and infrastructure to determine their structural integrity and recommend appropriate actions. Structurally compromised buildings should not be reoccupied unless certified safe by structural engineers.
Slopes should be checked for tension/incipient cracks that may have resulted from the strong ground shaking. Tension cracks may render slopes more susceptible to landslides, especially during heavy rainfall or aftershocks. Areas that may be affected by impending landslides should be avoided.
During earthquake events, rumors that may cause panic are easily spread. Please avoid sharing messages from unconfirmed and unreliable sources, and only rely on information from DOST-PHIVOLCS and respective Disaster Risk Reduction and Management Offices (DRRMOs).
What is the role of DOST-PHIVOLCS?
DOST-PHIVOLCS conducts seismic monitoring and provides earthquake information. In addition, DOST-PHIVOLCS also operates and maintains a network of 125 seismic stations spread across the Philippines. The closest seismic stations are the PHIVOLCS Visayas Cluster Monitoring Center for Earthquake and Tsunami (PVCMCET) in San Fernando, Cebu, the staff-controlled seismic stations in Lapu-Lapu City, Palo in Leyte, as well as remote seismic stations in Medellin, San Francisco and Dalaguete in Cebu, Cadiz City in Negros Occidental, Ormoc City in Leyte, Almeria in Biliran, and Talibon in Bohol. These stations are also augmented by the Kanlaon Volcano Network.
DOST-PHIVOLCS will deploy a Quick Response Team (QRT) to Cebu Province and vicinity. The DOST-PHIVOLCS QRT aims to assess impacts and hazards and conduct information dissemination campaigns to allay the fears of the public. Furthermore, DOST-PHIVOLCS works hand-in-hand with other government agencies in mitigating the damaging effects of the earthquake events in these localities.
Please visit our website at www.phivolcs.dost.gov.ph, and our Facebook (/PHIVOLCS) and X (@phivolcs_dost) accounts for earthquake information, volcano updates, hazard maps, and other information on earthquakes and volcanoes. Earthquake observations may also be reported to DOST-PHIVOLCS at telephone numbers (02) 8929-9254 and (02) 8426-1468 to 79, local 307 and 308, or through our official social media accounts.
Minor earthquakes: M3 to 3.9; Light earthquakes: M4 to 4.9; Moderate earthquakes: M5 to 5.9; Strong earthquakes: M6 to 6.9; Major earthquakes: M7 to 7.9; Great earthquakes: M8.0 and above.
References:
1. Bautista, M.L.P. and Oike, K. (2000). Estimation of the magnitudes and epicenters of Philippine historical earthquakes. Tectonophysics. Vol. 317. 137-169.
2. Southeast Asian Association of Seismology and Earthquake Engineering (SEASEE). (1985). In: Series on Seismology (Philippines) IV. Government Printing Office.
Washington D.C., USA.
3. Repetti, W.C., (1946). Catalogue of Philippine earthquakes, 1589–1899. Bulletin of the Seismological Society of America, 36(3), 133–319.
