Cebu has potentially active fault lines – PHIVOLCS

CEBU, Philippines - The Philippine Institute of Volcanology and Seismology (PHIVOLCS) revealed on Wednesday that there are several fault lines that are either active or potentially active that runs through Cebu’s cities and municipalities.

In a press conference yesterday in Cebu City, PHIVOLCS Officer-in-Charge Dr. Renato Solidum, Jr. said that the faults traced in the province have not moved, based on their monitoring.

“Areas that have no major earthquake in the past several hundreds of years would mean that these areas have seismic gap or big earthquake gap that when these faults will move, it may generate a strong earthquake,” said Solidum, also the undersecretary for Disaster Risk Reduction and Climate Change of the Department of Science and Technology.

He further explained that the longer period of time the fault has not moved, the more energy it stores.

Solidum said looking back at the past 100-year record, there were only minor earthquake events that occurred in Cebu, adding that there were only two significant quakes with over magnitude 6 in Central Visayas.

“There was in Negros and Bohol but no major earthquake in Cebu. Does it mean that Cebu is really safe from earthquake? The answer is no because there are faults in Cebu that can potentially move,” he said.

He also noted that the faults in Bohol and Mindanao are moving northwest while the fault line along Negros and Panay islands is moving east. Cebu, being in the middle, appears to be squeezed from both sides.

In the map presented yesterday, the "Bogo Fault" which transects Bogo City and San Remigio town is marked in red as an active fault while the rest of the faultiness across Cebu province are marked in black as potentially active faults, including the Daanbantayan Lineament.

Potentially active faults indicated as part of the Cebu Fault System, are subdivided into the "Central Cebu Fault" and the "South Cebu Fault."

About five fault lines were drawn in the map under the Central Cebu Fault that transects the cities of Danao, Cebu, Talisay, Naga, and Toledo and the towns of Compostela, Minglanilla and Balamban.

While the South Cebu Fault, also comprising of separate fault lines, transects Carcar City and the towns of Sibonga, Argao, Moalboal, Badian, Alegria, Dalaguete, Alcoy, and Boljoon.

For other towns and cities that have no fault lines, Solidum said they may not be affected by the ground rupture if an earthquake occurs but will still be affected by shaking.

Asked what damage these ground movements will cause in the event of an earthquake, Solidum responded indirectly, saying only that every city or town in the country will experience their own ‘big one’ at a certain point.

He said the disclosed information was not meant to scare the public but rather to give people a good grasp of the possible risk an earthquake may bring.

He added that knowing where the fault lines are is important so people will know whether sites are suitable for building houses. He said that even if a house or any structure is built near a fault, it may be spared from significant damage if designed and built properly.

These faults plotted in hazards maps were introduced to disaster-control units in Cebu province that are gathered for a two-day seminar and workshop to capacitate them in preparing for and responding to earthquake events.

They will also be trained to help PHIVOLCS in conducting an assessment that would translate the hazards maps to its possible impact such as providing an estimate on casualties and structural damages.

Aside from damaging structures, Solidum said strong earthquakes may also cause the loss of lives or injuries; may affect water, power, communication and transport systems; and may also disrupt public services and interrupt revenues from business or economic development.

Solidum said one could acquire a lesson from the recent magnitude 6.5 earthquake that struck Leyte last July 6, 2017.

“Cebu City is a very important city in the Philippines not only being one of the centers of governance but also in business. The effects in Cebu will also affect a big part of the country and also the whole of Cebu province,” he said. (FREEMAN)