RECONSTRUCTION efforts may proceed even as aftershocks from the magnitude 6.9 offshore earthquake in northern Cebu are expected to continue until December, according to the Philippine Institute of Volcanology and Seismology (Phivolcs).
The National Disaster Risk Reduction and Management Office reported that 733 infrastructures were damaged following the earthquake that struck northern Cebu.
Phivolcs Director Teresito Bacolcol, in a phone interview with SunStar Cebu on Tuesday, October 7, 2025, said there is no need to postpone the rebuilding of structures, as the aftershocks are expected to weaken in the coming weeks.
“Mahihina na yung mga aftershocks several weeks (Aftershocks weaken in several weeks). No need to postpone,” said Bacolcol.
Bacolcol said aftershocks following the powerful magnitude 6.9 earthquake are gradually decreasing but are expected to last for three months or until December.
While Phivolcs does not recommend postponing structural rebuilding efforts, Bacolcol stressed that no structures intended for human occupancy should be built directly on top of the Bogo Bay Fault.
He reiterated the recommendation to maintain a five-meter buffer zone on both sides of the fault.
Intensity
Nearly 2,000 aftershocks were recorded on the first day after the magnitude 6.9 quake that struck northern Cebu, but seismic activity has been steadily declining.
Bacolcol explained that aftershocks are normal after a strong earthquake, as the fault adjusts following the main rupture.
He said aftershocks are usually one magnitude lower than the main earthquake, adding that anything stronger than the main shock cannot be considered an aftershock.
According to Phivolcs, a total of 1,853 aftershocks were recorded after the earthquake on September 30.
Aftershocks dropped by 400 on October 1 and 2, with a total of 1,400 tremors recorded.
On October 3, 1,300 aftershocks were logged, followed by 1,028 on October 4.
The count continued to decline, with 988 aftershocks recorded on October 5 and 849 on October 6.
Bacolcol said that by December, or the 100th day since the earthquake, the number of aftershocks in Cebu is expected to drop further to 20 to 40.
He added that the increase in detected aftershocks can be attributed to more seismic stations in the country.
In 2013, there were only around 70 seismic stations operating nationwide.
Bacolcol said that with 125 stations now in place, more small earthquakes are being detected and recorded.
The earthquake, triggered by the Bogo Bay Fault Line identified by authorities on October 3, was the first major seismic event reported in Cebu in more than 400 years. (DPC)