Iloilo disaster office calls out gaps in quake tracking

By Mariela Angella Oladive

Retired Col. Cornelio Salinas, head of the Iloilo Provincial Disaster Risk Reduction and Management Office (PDRRMO), flagged the absence of a fully operational earthquake monitoring station in Iloilo as a major concern after the magnitude 6.9 tremor Tuesday night, Sept. 30.

The Philippine Institute of Volcanology and Seismology (PHIVOLCS) reported that the quake struck off the coast of Bogo City, Cebu, at 9:59 p.m., with an epicenter 17 kilometers north of the city.

The tectonic quake occurred at a depth of 10 kilometers.

Salinas said the lack of a functioning local monitoring station made it difficult to determine the precise intensity of the earthquake and calculate a safe waiting period before resuming government operations.

Work at the Iloilo Provincial Capitol was suspended as a precaution against aftershocks, while the Provincial Engineer’s Office (PEO) and PDRRMO conducted building inspections.

Capitol operations resumed at 1 p.m. Wednesday, Oct. 1.

“Why we couldn’t determine whether the standard waiting period should be 12 or 24 hours is because we don’t have an earthquake monitoring station to measure the specific intensity that affected the province, including the Capitol,” Salinas said.

“If there were an established station and the intensity was only 2 or 3, we could have shortened the waiting period. The problem is, we don’t have one. We have fault lines here in Panay Island, but there is no earthquake monitoring station in the province or anywhere on Panay Island,” he added.

Salinas said he coordinated with counterparts in Negros to compare readings, which ranged between Intensity IV and V.

He also contacted Iloilo City DRRMO Chief Donna Magno to ask about their findings and directed her team to check whether high-rise buildings had intensity meters installed.

Officials confirmed that none of the city’s buildings have the devices.

Salinas noted that while the Capitol has an intensity meter, it remains uncalibrated by the Department of Science and Technology (DOST).

In the absence of precise measurements, authorities relied on security personnel’s observations of furniture movement, building sway, and ground shaking to approximate the quake’s impact.

For context, magnitude measures the total energy released at an earthquake’s source, while intensity refers to the strength of shaking and its effects at specific locations, which can vary depending on soil conditions, structures, and distance from the epicenter.

Drone inspections were also used to assess old and new cracks in the 25-year-old Capitol building.

The PEO later confirmed the Capitol, including the Casa Real de Iloilo, is structurally sound, with only minor nonstructural defects in some areas.

Local reports show that PHIVOLCS inaugurated the Dueñas Iloilo Seismic Station (DUIP) in April 2022 as the first seismic station in the province.

The facility, located at the Central Azucarera de San Antonio Inc. sugarcane plantation in Brgy. Ponong Pequeño, Dueñas, is the 115th seismic station nationwide and part of the Philippine Seismic Network.

Dueñas Mayor Robert Martin Pama confirmed the station’s existence to Daily Guardian but said its operational status remains unclear.

PHIVOLCS has also inaugurated other seismic stations in Western Visayas, including the Ibajay Seismic Station in Aklan in 2018.

These facilities are intended to improve earthquake detection, ensure timely determination of quake parameters, and strengthen disaster preparedness and response.