THE Philippines’ top seismology official has said that reconstruction can start now, despite an ongoing swarm of aftershocks.
The big picture: Aftershocks from the magnitude 6.9 northern Cebu earthquake are expected to continue until December, but they are gradually weakening, according to the Philippine Institute of Volcanology and Seismology (Phivolcs).
The earthquake, triggered by the newly identified Bogo Bay Fault, caused damage to 733 infrastructures in northern Cebu.
What they’re saying
No postponement: Phivolcs Director Teresito Bacolcol, in a phone interview with SunStar Cebu on Tuesday, Oct. 7, 2025, said there is no need to postpone structural rebuilding efforts.
He explained that the aftershocks are expected to weaken in the coming weeks.
The fault line: Bacolcol said that no structures intended for human occupancy should be constructed 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 line.
Aftershock intensity
Nearly 2,000 aftershocks were recorded on the first day after the magnitude 6.9 quake, but the seismic activity has been steadily declining.
Bacolcol said aftershocks are normal, as the fault adjusts following the main rupture.
Aftershocks, he said, are usually one magnitude lower than the main earthquake, and anything stronger cannot be considered an aftershock.
By December, which will mark the 100th day since the earthquake, the number of aftershocks is expected to drop further to 20 to 40 per day, according to Bacolcol.
By the numbers
A total of 1,853 aftershocks were recorded following the Sept. 30 earthquake.
The count dropped to 1,400 tremors recorded on Oct. 1 and 2.
The decline continued, with 1,300 logged on Oct. 3, 1,028 on Oct. 4, 988 on Oct. 5, and 849 on Oct. 6.
The increased detection of smaller earthquakes is attributed to the presence of 125 seismic stations nationwide, a significant increase from around 70 operating in 2013.
Plus, this: Phivolcs has also observed coastal uplift — approximately one meter of rise in the coastline — in Barangay Nailon, Bogo City, which resulted from the Bogo Bay Fault movement during the earthquake.
The uplift is evident from exposed tidal flats, raised tidal notches and higher high-tide markers. The dried up sea grass indicates that the area used to be submerged underwater, while the raised notches indicate uplift of the coastline near the Bogo Bay Fault during the earthquake. / DPC, TPM / PHILIPPINES