ANGELES CITY- The government’s chief geologist said yesterday lahar threat from Mt. Pinatubo has become minimal and that danger to local communities during unusually heavy rainfall would likely be from riverbank erosion as was experienced in this city during the last monsoon rains.
“Morphology on the slopes of Mt. Pinatubo has remained such that if any remobilization of sediments occur, the flow would still be towards the Sacobia River,” said Dr. Arturo Daag, chief of the geology department of the Philippine Institute of Volcanology and Seismology (Phivolcs) in an interview.
This city used to be directly threatened by lahar flows after Mt. Pinatubo’s eruption in 1991, but natural events on the volcanic slopes diverted the flows towards the Sacobia River which winds through the boundary of Pampanga and Tarlac.
“I don’t think that Angeles would be threatened again by lahar flows. For one thing, the materials dumped by the 1991 eruption have almost been dissipated. And then, the fact is that the deepening of the channel of Sacobia River years ago as a result of secondary explosions on the slopes has continued to protect Angeles,” he said.
Daag noted that at the headwaters on the volcanic slopes, Sacobia River is about 40 meters deeper than Abacan River which winds through Angeles.
“This was the reason why some time after the eruption, Angeles all of a sudden was spared from lahar flows,” he recalled.
But he warned while lahar materials no longer pose serious threat, waters flowing through former lahar channels, such as the Abacan and the Sacobia rivers, would likely erode riverbanks.
During the recent monsoon rains, this city’s Mayor Edgardo Pamintuan ordered the demolition of shanties and other structures on the entire stretch of the banks of the Abacan River amid “serious danger of erosion.”
Reports said that 78 of such houses have already been eroded into the river during the monsoon rains.
“Our concern here is the safety of our people living along the dangerous river bank,” said Pamintuan in his directive.
He stressed that “the city government has to enforce the law,” referring to a local law banning people from living in areas threatened by natural disasters.
“No one can toss the blame to the city government should the worst happen to folk living on the river banks,” he said.
