BACOLOR, Pampanga – Amid some panic triggered by reports that an anti-lahar dike at the Pasig-Potrero river here could give way, the Philippine Institute of Volcanology and Seismology (Phivolcs) assured local folk yesterday that threat from the river, which had served as a major channel for Mt. Pinatubo’s deadly lahar flows in the 1990’s, has remained insignificant.
Reports in local media yesterday raised alarm, even some panic, over alleged threats to the integrity of the P2.7- billion anti-lahar megadike at the river amid expectations of La Niña rainy weather this year. The U-shaped megadike, which served as catch basin during severe lahar flows in 1990’s, had protected the capital city of San Fernando, and other highly populated areas from being buried by lahar debris from Mt. Pinatubo.
In an interview with Punto, Ma. Isabel Atigania, officer-in-charge of the geology division of Phivolcs, said 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 episode along 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 remobilized lahar flows,” she noted.
Before the megadike was finished in 1996, lahar flows from the Pasig-Potrero buried parts of San Fernando, Porac, and almost all this town, under several meters of lahar materials
While downplaying lahar threat from Pasig-Potrero, Atigania nevertheless said that the megadike needs to be maintained.
The eastern portion of the U-shaped megadike was also converted into a road serving as shorter route between Porac and Bacolor.
Provincial environment officer Art Punsalan reported, however, that concrete beams providing some 2.7-meter clearances across some parts of the dike road have vanished. The beams prevented heavy dump trucks hauling lahar sand from accessing the road as a measure to preserve it. He sought the restoration of the beams.
Only recently, Gov. Lilia Pineda and engineers from the Japan International Cooperation Agency (JICA) which had provided funds for the dike, inspected the 56-kilometer structures and found several portions in need of repair.
While citing the need for a regular maintenance of the megadike, Atigania nevertheless said she knew of no immediate danger to surrounding communities.
“If there are people who are threatened, they are those who have rebuilt houses, even concrete ones, right within the megadike which are permanent danger zones,” she noted.
Atigania said she has observed such rebuilt structures within the dike in Porac and Bacolor. “They are not really squatters. I was told they own the lands where their old homes and farms were buried by lahar flows and they came back to reclaim their lands after lahar flows ceased to affect their properties,” she added.
Atigania said that the only way to protect these folk is through early warning systems and protective structures if they opt to stay on within the diking system.
She also said that lahar threat at the Sacobia river between Pampanga and Tarlac have remained insignificant. She said that such flows could still occur from Mt. Pinatubo up to the Sacobia river traversing a portion of Clark freeport, but downwards toward the MacArthur highway, the flow would tend to spread to cause mere flooding and mild “deposition” downstream.
Reports in local media yesterday raised alarm, even some panic, over alleged threats to the integrity of the P2.7- billion anti-lahar megadike at the river amid expectations of La Niña rainy weather this year. The U-shaped megadike, which served as catch basin during severe lahar flows in 1990’s, had protected the capital city of San Fernando, and other highly populated areas from being buried by lahar debris from Mt. Pinatubo.
In an interview with Punto, Ma. Isabel Atigania, officer-in-charge of the geology division of Phivolcs, said 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 episode along 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 remobilized lahar flows,” she noted.
Before the megadike was finished in 1996, lahar flows from the Pasig-Potrero buried parts of San Fernando, Porac, and almost all this town, under several meters of lahar materials
While downplaying lahar threat from Pasig-Potrero, Atigania nevertheless said that the megadike needs to be maintained.
The eastern portion of the U-shaped megadike was also converted into a road serving as shorter route between Porac and Bacolor.
Provincial environment officer Art Punsalan reported, however, that concrete beams providing some 2.7-meter clearances across some parts of the dike road have vanished. The beams prevented heavy dump trucks hauling lahar sand from accessing the road as a measure to preserve it. He sought the restoration of the beams.
Only recently, Gov. Lilia Pineda and engineers from the Japan International Cooperation Agency (JICA) which had provided funds for the dike, inspected the 56-kilometer structures and found several portions in need of repair.
While citing the need for a regular maintenance of the megadike, Atigania nevertheless said she knew of no immediate danger to surrounding communities.
“If there are people who are threatened, they are those who have rebuilt houses, even concrete ones, right within the megadike which are permanent danger zones,” she noted.
Atigania said she has observed such rebuilt structures within the dike in Porac and Bacolor. “They are not really squatters. I was told they own the lands where their old homes and farms were buried by lahar flows and they came back to reclaim their lands after lahar flows ceased to affect their properties,” she added.
Atigania said that the only way to protect these folk is through early warning systems and protective structures if they opt to stay on within the diking system.
She also said that lahar threat at the Sacobia river between Pampanga and Tarlac have remained insignificant. She said that such flows could still occur from Mt. Pinatubo up to the Sacobia river traversing a portion of Clark freeport, but downwards toward the MacArthur highway, the flow would tend to spread to cause mere flooding and mild “deposition” downstream.
