ANGELES CITY- Will unusually heavy rainfall now seemingly common in the country and other parts of the world eventually lead to the collapse of the country’s deepest lake atop Mt. Pinatubo and wipe out this city and other towns in Central Luzon?
Dr. Arturo Daag, chief of the geology department of the Philippine Institute of Volcanology and Seismology (Phivolcs), debunked such fears yesterday following flooding in areas around Mt. Pinatubo amid the recent monsoon rains induced by tropical depression Maring.
“The walls of the 2.5-kilometer wide crater lake have remained strong like welded lahar materials. Their strength is such that they withstood Mt. Pinatubo’s eruptions in 1991,” Daag said in a phone interview with Punto.
The increasing frequency of unusually heavy rains in the country, as well as other places, have triggered fears from folk in communities that used to be threatened by lahar flows from Mt. Pinatubo’s slopes after the volcano’s eruption in 1991.
The eruption created a so-called caldera that led to the creation of the crater-lake at Mt. Pinatubo’s summit at the tri-boundaries of Zambales, Pampanga and Tarlac. Now a tourist attraction, the lake is reputed to be the country’s deepest at 800 meters.
Daag recalled that fears over the collapse of the lake heightened in 2001 when the lake waters started to fill up and rise at the rate of 1.24 meters a month. This prompted Phivolcs scientists to propose the creation of a permanent draining point at the lowest point of the crater wall in Barangay Maraunot in Botolan, Zambales.
He noted that the following year, government engineers removed the soft layers of the notch down to the level of strong materials of “welded lahar” estimated to be 2,500 years old.
The notch came to be known as the Maraunot notch which now serves as permanent drainage canal to siphon off the lake’s waters into the Maraunot River and then on to the Balin-Baquero Rivers before reaching the Bucao River in the Botolan valley leading to the South China Sea.
“The Bucao River has a wide watershed capable of accommodating the waters flowing from the crater lake via the Maraunot notch,” he added.
Daag also noted that the second lowest point of the crater wall is located at O’Donnel in Capas, Tarlac, but stressed that this point is about 40 meters above the normal level of the crater lake.