Phivolcs to Pampanga townsfolk: Lahar threat insignificant

BACOLOR, Pampanga, Philippines – The Philippine Institute of Volcanology and Seismology (Phivolcs) yesterday assured residents here that the lahar threat from the Pasig-Potrero River here, which served as a major channel for Mt. Pinatubo’s deadly lahar flows in the 1990s, has remained insignificant.

This, as local media reports raised alarm, even panic, over supposed threats to the integrity of the P2.7-billion anti-lahar megadike along the river with the onset of the typhoon season.

The U-shaped megadike, which served as catch basin during severe lahar flows in the 1990s, had protected the capital city of San Fernando and other highly populated areas from being buried by lahar debris from Mt. Pinatubo.

Ma. Isabel Atigania, officer-in-charge of Phivolcs’ geology division, told The STAR that “no aggravating factor” has so far changed the long-term worst scenario assessment done during the multi-agency lahar hazard mapping in 2007.

The assessment indicated that dangerous lahar episodes along the Pasig-Potrero had already ceased.

“The threat at the Pasig-Potrero River remains within the megadike, and even this has been calculated to be limited to moderate re-mobilized lahar flows,” she said.

Before the megadike was finished in 1996, lahar flows from the Pasig-Potrero buried parts of San Fernando, Porac and almost this entire town under several meters of lahar.

While downplaying the lahar threat from the Pasig-Potrero, Atigania nevertheless said the megadike needs to be maintained.

The eastern portion of the U-shaped megadike was also converted into a road serving as a shorter route between Porac and Bacolor towns.

Provincial environment officer Art Punsalan, however, reported that concrete beams providing a clearance of 2.7 meters across some parts of the dike road have vanished.

Punsalan sought the restoration of the beams, which had prevented heavy dump trucks hauling lahar sand from accessing the road.

Recently, Gov. Lilia Pineda and engineers of the Japan International Cooperation Agency, which funded the megadike, inspected the 56-kilometer structure and found several portions in need of repair.

While citing the need to regularly maintain the megadike, Atigania though said she knew of no immediate danger to surrounding communities.