Pinatubo crater rim not cracking up, says scientist

CLARK FIELD, Pampanga — The resident volcanologist of the Philippine Institute of Volcanology and Seismology (Phivolcs) here clarified yesterday that the crater rim of Mt. Pinatubo is not about to crack contrary to the alarm which the Regional Disaster Coordinating Council (RDCC) raised.

"What was observed as a crack on the Zambales side of the crater rim was merely a natural gully with a spring whose water source is not even the crater lake," said volcanologist Jaime Sincioco.

Earlier, Senior Superintendent Reynaldo Berroya, Central Luzon police director and RDCC chief, said the crater lake level was alarmingly only about five meters from the lowest point or notch of the crater rim facing Botolan, Zambales.

"We are not discounting the catastrophic scenario but our perception at this point is that the situation is not that alarming," Sincioco said.

He said that Assistant Secretary Florante Soriquez of the Department of Public Works and Highways (DPWH) has submitted four engineering options to prevent a possible disastrous overflow of the crater lake through the notch to the Maraunot River.

"Among the four proposals, Phivolcs and experts from the (Japanese engineering firm) Nippon Koei agreed that the scrapping of the soft outer lahar of the Maraunot notch is the best option," he said.

Sincioco cited studies showing that the notch is layered with about 13 meters of soft material which could be scrapped to expose the underlying bedrock and allow the smooth overflow of the crater lake. Otherwise, the soft portion could suddenly give way due to pressure from the lake’s rising level.

The lake’s level is expected to reach the notch anytime this year, depending on the rainfall.

Sincioco said the crater lake is now about 94 meters deep and holds about 164 million cubic meters of water.

"The lake is about 2.6 million square meters in a crater which is about 300 hectares," he added.

Sincioco said a one-meter rise in the lake’s level means an additional three million cubic meters of water added to the lake’s volume.

He said that should the lake collapse, it would not possibly cause devastation in Botolan town where some 46,000 families reside.

"Botolan is about 40 kilometers from the crater. Any breakout from the crater would flow to the Maraunot and Balin-Baquero rivers which lead to the South China Sea," he said.

Sincioco, however, asked the RDCC to check whether Aetas, who had earlier abandoned their villages in Villar and Morasa near the Maraunot River, have returned.

He said the Aetas’ villages could be in danger if the crater lake collapses at the Maraunot notch.