CLARK FREEPORT -- The Philippine Institute of Volcanology and Seismology (Phivolcs) Director Renato Solidum clarified that his statement regarding the lahar threat is not meant to scare people but to let them prepare for any disaster that may occur during the rainy season.
Solidum said earlier that the eruption of Mount Pinatubo is over but the lahar, which is a mixture of water and sediments, has been a lingering threat.
“We are not raising people to panic but we need to make sure that they are ready. That kind of scenario is not over, it should always be considered and I’ve been mentioning this ever since,” Solidum said.
He added that Phivolcs never issued certifications to residents to build houses inside a megadike.
Solidum suggested that the FVR megadike in Pampanga should be maintained and dredged continuously to prevent flooding and protect the residents in low-lying areas in the province.
"We have to make sure that these are strong enough to prevent erosion," he said.
He added that the Department of Public Works and Highways should monitor the dikes regularly especially during heavy rains.
Solidum earlier revealed that heavy rains that will be brought about by an Ondoy-like typhoon may trigger lahar flows and flooding in Pampanga.
He issued the statement during a briefing with Pampanga-based newsmen belonging to the Capampangan In Media Incorporated at the Bale Balita here on Friday, June 24.
“The river get shallower nasi-silt siya. In short, hindi yan nakakamatay until na magkaroon ka ng sobrang lakas ng ulan and in a short duration, iaanod muli yung napondo doon at kung hindi ma-contain ng dike ay baka lumampas,” Solidum said.
In 2008, a study conducted by Phivolcs in Pampanga revealed that continuous rains may repeat massive flooding like the monsoon rains (siyam-siyam) in 1972 that submerged many areas in Central Luzon.
“Yung siyam-siyam, yun ang kailangan nating bantayan. For example, our modeling said if we assume 10 million cubic meters of lahar, which immediately after the eruption ay nangyari yun, so what can happen is that the flow can start depositing above doon sa SCTEX point sa Delta 5 watch-point. Kung doon nagsimula banda ang deposition baka dito sa may Mancatian area ay abutin doon. So babantayan natin na ang flow at yung ilog ay hindi doon kasi ang tendency ng tubig papunta doon e,” Solidum said.
He suggested “flood-quarrying” or an “engineered-design” quarrying along the Pasig-Potrero river and other adjacent river channels in order to prevent heavy siltation, which may threaten several villages inside the FVR megadike.
An estimated 4,000 families resides in several Pampanga towns located inside the megadike, which was built during the time of President Fidel Valdez Ramos after lahar remobilized by rain overflowed from the Pasig-Potrero River on October 1, 1995, burying Bacolor town.
“Yung Angeles-Porac road tumatawid doon, bantayan niyo kung bumababaw yan. Kaya ang suggestion nga namin, kung magku-quarry, dapat engineered ang design para nakakatulong ka pa sa dredging para ilayo mo doon sa delikadong parte at igitna mo [sa ilog] kasi kung doon parati doon pupunta ang lahar baka umapaw doon,” Solidum said.
He said that over the past few years, no strong typhoons hit Central Luzon and Pampanga that may have triggered massive flooding and affect residents inside the megadike and other low-ying areas around the province’s flood-defense structure.
“Ang issue is apparently now, if we just consider the normal rain walang masyadong nangyayari sa loob ng megadike. Pero paano kung lumake, so what will happen to the people who have rebuild inside [the megadike],” Solidum said.
People living inside the megadike should understand the threat, he added.
“Ang point ko lang ay huwag tayong pakakampante. Logic lang, kinulong mo ang tubig sa isang megadike, therefore ang megdike ang purpose niya ay saluhin ang tubig at lahar. Ang main threat diyan ay yung nasa loob. Ngayon, sa lapad naman ng ilog at megadike ay hindi naman natin alam kung saan ang tumbok,” Solidum said. (Sun.Star Pampanga)