There had been concerns that the operation, which is considered one of the largest of its kind ever recorded, may run out of control as the emergency spillway let out 24 million cubic metres of water, 11.5% of the crater’s total volume, and some 40,000 residents of the town of Botolan had been evacuated as a precautionary measure.
However, when edie was published, the water was flowing in a steady and controlled way from the crater lake, which was formed when Mount Pinatubo erupted in 1991, and which was in danger of spilling over onto communities below. Government volcanologists had requested the construction of a spillway, and guided by engineers, more than 100 members of the local Aeta tribe spent more than 12 days using only picks and shovels to dig out a canal. The use of earthmoving vehicles had been ruled out as there are no roads on the slopes of the volcano, and the unstable ground ruled out the use of explosives.
The Philippine Institute of Volcanology and Seismology said that Pinatubo’s crater was breached two metres wide and 12 inches deep and the diversion canal was built 100 metres wide to allow water to flow very gently.
The Philippines’ recently-appointed president, Gloria Macapagal-Arroyo, has already flown to the scene of the Pinatubo diversion, which is about 100 kilometres (63 miles) northwest of the capital Manila, to inspect the diversion project, although the presidential office warned that some communities are still considered high-risk areas.