THE magnitude 6.9 earthquake that struck off the coast of Bogo City on Tuesday night, Sept. 30, 2025, has become the most powerful tremor ever recorded in Cebu, according to the Philippine Institute of Volcanology and Seismology (Phivolcs).
The quake hit at approximately 9:59 p.m., with its epicenter located 21 kilometers northeast of Bogo City in northern Cebu. The shallow depth of just five kilometers amplified its destructive power, registering Intensity 7 near the epicenter.
Why was this tremor so powerful
Phivolcs Director Teresito Bacolcol explained that the earthquake’s shallow depth made it particularly destructive. “Usually, seismic energy weakens as it travels toward the surface. When the seismic energy originates from a deep source, it loses strength as it travels upward, so by the time it reaches the surface, it has lost much of its force. But here, at just five kilometers deep, as it traveled toward the surface, the energy hadn’t reduced much yet, so when it reached the surface, the energy was still strong, which is why the damage was so extensive,” Bacolcol said in a phone interview with SunStar Philippines.
The tremor was felt across a vast area, reaching as far as Sorsogon, Zamboanga del Norte and Misamis Oriental.
Was the Bogo fault responsible
Despite Bogo City having its own fault line, Bacolcol clarified that the earthquake originated offshore, not from the Bogo fault on land. “We have a Bogo fault, but it wasn’t what produced last night’s earthquake. The Bogo fault is on land, while the earthquake last night was produced offshore, in the sea, so they are different,” he said.
While movement in one fault can trigger activity in another, Bacolcol said the faults must be within five kilometers of each other for this to occur. “The faults have to be very close to each other, around five kilometers distance. But in this case, they’re far apart. It could happen if they were close together, but as I mentioned, the epicenter is far away in the sea,” he added.
What about the tsunami warning
Phivolcs issued a tsunami warning from 9:59 p.m. Tuesday until 1:20 a.m. Wednesday. The agency lifted the warning after monitoring showed no significant changes in sea levels.
Is there a connection to Taal Volcano
The earthquake occurred the same day Taal Volcano erupted at 2 a.m. Tuesday. Bacolcol confirmed these events were unrelated. “There’s no connection between them because we have 24 active volcanoes and we also have 180 active fault segments spread all over the country, so there’s always a chance or possibility that these events could happen simultaneously,” he said.
Taal Volcano remains under Alert Level 1, indicating low-level unrest.
How does this compare to other major earthquakes
The magnitude 6.9 quake now ranks as Cebu’s strongest recorded earthquake. At least eight major earthquakes have struck the Visayas in recent years, ranging from magnitude 5.0 to 7.2. The 2013 Bohol earthquake held the regional record at magnitude 7.2.
The strongest earthquake in Philippine history remains the magnitude 7.8 Luzon earthquake of July 16, 1990.
What precautions should residents take
Phivolcs warned that aftershocks could cause weakened buildings to collapse. Bacolcol advised residents to consult municipal or city engineers before entering structures showing visible damage. The agency urged the public to stay away from damaged buildings and other weakened structures that aftershocks could topple. / TPM, MVE