“Prepare for the Big One”; Phivolcs warns Valley Fault residents

From philstar.com:
By Helen Flores

MANILA, Philippines – Residents of Metro Manila and nearby provinces should prepare for the “Big One,” a magnitude 7.2 earthquake to be generated by the West Valley Fault, which is ripe for movement.

Amid the devastation caused by the magnitude 6.7 earthquake in Surigao, the Philippine Institute of Volcanology and Seismology (Phivolcs) yesterday appealed to residents of Metro Manila and nearby provinces to prepare for a powerful earthquake that could kill thousands.

“Everyone must learn from the recent effects of the magnitude 6.7 earthquake in Surigao del Norte. If a similar event happens in a highly urbanized area, the effects can be more devastating,” Phivolcs director Renato Solidum warned.

State seismologists have repeatedly warned the public that the West Valley Fault is ripe for movement.

The West Valley Fault, Solidum said, moves roughly every 400 years. The last major earthquake generated by this fault was in 1658 or 357 years ago.

The 100-kilometer fault traverses parts of Bulacan through Quezon City, Marikina, Makati, Pasig, Taguig and Muntinlupa in Metro Manila; San Pedro, Biñan, Sta. Rosa, Cabuyao and Calamba in Laguna; and Carmona, General Mariano Alvarez and Silang in Cavite.

A 2004 study funded by the Japan International Cooperation Agency for Phivolcs and the Metropolitan Manila Development Authority showed that the magnitude 7.2 quake could kill up to 34,000 people and injure 100,000 others due to collapsed buildings.

Solidum explained that the movement of the Philippine Fault (Surigao segment) would not trigger the movement of faults farther like the West Valley Fault.

Phivolcs continued to record aftershocks from the magnitude 6.7 quake that hit Surigao last Friday night, killing at least eight people and injuring hundreds.

More than 150 aftershocks have been recorded as of yesterday morning, Phivolcs said.

At 3:51 a.m. yesterday, an aftershock of magnitude 4.1 struck Surigao. It was reportedly felt at Intensity 3 in the city.

Phivolcs earlier warned the public to brace for more aftershocks from the magnitude 6.7 quake that could collapse already damaged structures.

Eastern Mindanao, including Surigao del Norte, is one of the earthquake prone areas in the country because of the Philippine Fault and Philippine Trench.