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Explained: Why the Philippines is one of the world’s most earthquake-prone countries
Monday’s quake mirrored the incident that happened nearly 50 years ago on August 17, 1976 called the Moro Gulf Earthquake, but with fewer casualties
- PUBLISHED: Tue 9 Jun 2026, 6:00 AM UPDATED: Tue 9 Jun 2026, 12:29 PM
The intensity 7.8 earthquake off the southern coast of Mindanao Island on Monday, June 8, was the strongest tremor the Philippines has suffered in nearly five decades. The Office of Civil Defence (OCD) said the death toll has reached at least 40, with hundreds of residents injured.
Aside from commercial buildings and school houses across two island regions, local authorities reported that a stretch of highway in South Cotabato Province collapsed as a result of the quake, cutting off access to the upland tourist town of T’boli.
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Monday’s quake mirrored the incident that happened nearly 50 years ago on August 17, 1976 called the Moro Gulf Earthquake, but with fewer casualties.
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What was the Philippines deadliest quake in the last century?
Filipinos are no strangers to strong earthquakes. Located right where the Pacific Ocean plate meets the Asiatic tectonic plate, the country experiences an average of 7,300 earthquakes annually, up to 150 of them classified as "strong". Monday’s tremor is classified as "destructive" by the national seismology agency.
The incident had been identified by the Philippine Institute of Volcanology and Seismology as having been caused by the active undersea furrow called the Cotabato Trench. Monday’s earthquake produced a moderate 1 metre tsunami in several coastal areas in Mindanao.
The Cotabato Trench also caused the 1976 event, whose accompanying 9-metre tsunami killed up to 8,000 victims. The Moro Gulf Earthquake is the Philippines’ deadliest tremor, killing more victims than the stronger 1918 Magnitude 8.3 Celebes Sea earthquake that the Cotabato Trench also caused in almost exactly the same spot. The earlier tectonic rupture reportedly produced an 8-metre tsunami that killed 52 victims.
How strong is an intensity 7.8 earthquake?
A 7.8 magnitude quake is mathematically equivalent to the energy of roughly 30 to 40 million tonnes of TNT, which in turn is equivalent to 2,000 to 2,667 Hiroshima bombs. It is likewise significantly more powerful than the 1906 San Francisco earthquake that destroyed the entire city.
An earthquake magnitude measures the total energy released at the source. Its intensity, meanwhile, refers to the actual shaking experienced by residents in the affected area. Intensity also refers to the physical damage done in a specific area, such as the collapsed buildings and highways reported in Monday’s earthquake in the Philippines.
How prepared is the Philippines for earthquakes?
As one of the world’s most disaster-prone countries, the Philippines had actually been preparing for what it calls “The Big One", but it is not the movement by the Cotabato Trench that the country is most afraid of. It is by the Manila Trench, which the government said is due for a rupture based on a 50-year cycle.
The Manila Trench lies on the eastern boundary of Metropolitan Manila, which has about 14 million residents. Its dense population is most vulnerable should an equally strong earthquake happen in the area. Many of its buildings do not adhere to the intensity 7.0 threshold that has only been recently implemented.
Since 2006, the country’s Office of Civil Defence and the National Disaster Risk Reduction and Management Council (NDRRMC) conceptualised the Nationwide Simultaneous Earthquake Drill (NSED) in 2006. This initiative was created in response to the devastating earthquake that struck Yogyakarta, Indonesia, earlier that same year.
An earthquake cannot be predicted. But as various videos of Monday's event have shown, Filipino teachers automatically tried to calm their students who, in turn, were able to follow instructions despite their obvious terror.
The earthquake drills had been regularly held, several times a year, in schools and government offices most of all. Monday’s destructive earthquake would have been much worse if it happened a few minutes later when the schoolchildren were already inside the school buildings and without the simulations and drills.
Rescue operations ongoing
Search and rescue operations will continue across the affected areas. Government and civic emergency teams are doing extrications, debris clearing, and disaster relief.
A major city close to the quake’s epicentre is General Santos City, which is hardest hit by the event. Responders from the Philippine Red Cross and the Bureau of Fire Protection are conducting heavy searches at a collapsed commercial facility near the city centre. K-9 units of the Philippine Coast Guard are also deployed for search operations.
Philippine President Ferdinand Marcos is allowing emergency funds in all government agencies to be used for relief operations. All other non-emergency operations have been suspended “until further notice".
