WHEN a magnitude 6.9 earthquake rocked Cebu on the night of Sept. 30, 2025, the ground heaved, roads cracked open and coastlines permanently altered.
But amid the visible destruction lies an even more alarming reality: the Philippines is sitting on top of 185 active fault segments and 30 fault systems, yet the country only has 125 seismic stations monitoring them.
The number is less than half of the 300 stations that the Philippine Institute of Volcanology and Seismology (Phivolcs) needs to properly monitor seismic activity across the archipelago.
At the current rate of government funding, Phivolcs Director Teresito Bacolcol said the agency can only install four new stations per year.
With this pace, Bacolcol said completing the network will take four decades.
However, the earth cannot wait for 40 years before it will move again.
Phivolcs is operating a network of seismic stations to monitor earthquake activity across the country, with a primary goal to provide accurate and timely information on earthquakes and to strengthen the country’s ability to monitor and respond to seismic events.
Bacolcol, in an interview with SunStar Cebu’s online news and commentary program Beyond the Headlines, said one seismic station costs around P8 million for construction and equipment.
In 2024, Phivolcs was given P65.4 million for the construction of seismic stations and equipment.
He said for the size of the Philippines, it requires 300 seismic stations.
However, with the budget given to the agency under the General Appropriations Act, Bacolcol said Phivolcs can only establish four seismic stations a year.
He took for example how equipped Taiwan is. He said Taiwan, which is one-tenth the size of the Philippines, has 290 seismic stations.
With a dense network of seismic stations, scientists can pinpoint an earthquake’s location, depth and magnitude, which helps in providing early warnings and studying the earth’s interior, according to the US Geological Survey.
Bacolcol said aside from the funding, Phivolcs is also limited in terms of the number of personnel.
When the earthquake occurred in Cebu, several residents reported receiving phone alerts after they felt the ground shaking.
Bacolcol explained there was a delay of alerts since the country does not have a nationwide P-wave early warning system yet, a technology used in earthquake-prone countries like Japan and Taiwan.
During an earthquake, there are two types of waves the earth generates, the primary, or P-wave, and secondary, or the S-wave, according to Bacolcol.
The P-wave travels faster and can move through solids, liquids and gases, followed by a slower S-wave that only travels through solids and is considered more destructive.
Bacolcol said if P-waves are detected, it would send signals to a processing center like cellphones to issue a warning and would be able then to calculate the arrival of the S-wave.
“The people living close to the epicenter may receive little or no warning at all as the S-waves would follow immediately after the P-wave. But those farther away may have more time to prepare before the shaking starts,” said Bacolcol.
Aside from a dense network of seismic stations, Bacolcol said a stable internet connection is required to implement a real-time P-wave alert system.
The magnitude 6.9 earthquake was triggered by the Bogo Bay Fault -- a fault only identified after it ruptured. It is a strike-slip fault which is horizontal in motion.
Phivolcs traced its onland extension, about eight kilometers, in Sitio Looc, Barangay Nailon in Bogo City on Oct. 3.
“Now, the next question is, does the Bogo Bay fault already exist? For sure, it already exists. But we have no record for the past 400 years. So, if you look at the historical record of northeastern Cebu, it has no record,” said Bacolcol.
He said a big part of the fault is in the sea and the regular mapping of Phivolcs is focused on land.
For a fault to generate a 6.9 earthquake, Bacolcol said it should be around 40 to 50 kilometers long, which means a big portion of the fault lies offshore.
The epicenter of the magnitude 6.9 earthquake is located 21 kilometers northeast of Bogo City.
“Offshore active faults are also hazardous, like what we’ve seen in Bogo City. But their mapping requires a different set of resources, as well as methodologies, and a different set of expertise.”
Phivolcs Director Teresito Bacolcol
In April, the Phivolcs Modernization Act was passed. It aims to provide the agency with state-of-the-art equipment, highly trained personnel and more seismic stations that would increase the capability to detect and locate earthquake, volcanic, and tsunami events.
The law will be implemented for five years.
Under the law, an amount of P1.25 billion per year for the first four years and P2 billion for the fifth year will be appropriated for the Phivolcs Modernization Fund.
Key provisions under the law include:
Physical resource upgrade: Upgrade physical resources and operational standards through the acquisition and development of state-of-the-art instruments, equipment, facilities and systems.
Network expansion: Expand volcanological and seismological monitoring stations in strategic sites across the country to broaden the base for service delivery.
Forecasting capability: Develop forecasting capability for impending major earthquakes or tsunami events.
Data center strengthening: Strengthen a state-of-the-art data center consistent with international standards.
Data receiving center (DRC): Establish a fully equipped, state-of-the-art DRC that will serve as Phivolcs’ centralized hub for the reception, processing, visualization and dissemination of real-time earthquake, tsunami and volcano monitoring data.
Research facility enhancement: Enhance the research and development facility through the establishment of state-of-the-art earthquake and volcano research laboratories, focusing on transdisciplinary approaches.
Hazard and risk platforms: Establish and regularly update the Phivolcs hazards and risk information platforms, specifically mentioning GeoRiskPH and the Rapid Earthquake Damage Assessment System platforms, for data sharing and risk mitigation.
Bacolcol said through the modernization program, Phivolcs will be able to densify its monitoring network and establish a robust information system that will improve the monitoring capability of the agency. / with reports from DPC