Tugging along a leashed pig to sacrifice to the mountain god, the Aeta tribesmen were to carve a notch in the volcano’s crater to bleed water from the rising lake.
The workers, accompanied by a dozen porters, two engineers and others, were expected to chop five meters off the lowest point of Pinatubo’s summit and drain the lake that has risen to within five meters of the crater’s rim.
Raymundo Punongbayan, director of the Philippine Institute of Volcanology and Seismology, said it is believed to be the first attempt in the world to drain water from a volcano lake in such a manner.
He said water has been drained from the Kelud volcanic lake in Indonesia by boring through the crater wall. He said that procedure would be too expensive for the cash-strapped Philippines.
Without the canal, the weight of the water that has been rising rapidly in the May-October rainy season, could shatter upper walls of the 1,445-meter volcano and endanger 40,000 villagers nearby, geologists said.
Willy Bulanhigan, a 45-year-old worker who was to supervise the digging, said the Aeta diggers, would sacrifice the pig and pour a bottle of gin on the crater rim before beginning work to appease the supreme Aeta god who they believe lives in the volcano.
The diggers are paid P180 a day and were given picks, shovels and wheelbarrows, along with a week’s supply of rice and canned food.
Government geologists, supervising and planning the work, ruled out the use of explosives or heavy equipment for fear it could unpredictably tear away at the crater.
Local officials said as many as 200 men will be needed to complete the operation over the next two weeks or so.
On completion of the initial five-meter notch, geologists predict another five meters of already-weakened wall would give way, draining 15 million cubic meters of the lake’s 200 million cubic meters of water in five hours.
About 200 villagers in the likely path of the water flow have moved to safer areas.
A new study released yesterday by the Phivolcs revealed that unless Mt. Pinatubo’s crater lake is artificially breached soon, its collapse could unleash 150 to 300 million cubic meters of lahars roaring down the slopes at a maximum rate of 11,000 cubic meters per second.
"That’s why the artificial breaching of the Maraunot notch should be done immediately," said Jaime Sincioco, resident volcanologist of the Phivolcs at Clark Field.
The study also said that without artificial intervention, the Maraunot notch could collapse in 15 minutes to three hours after the start of the overflow of the crater lake which would reach the notch by the latter part of this September. — Ding Cervantes