30% of medium-rise buildings to be affected by magnitude 7 quake

MANILA, Philippines -The Philippine Institute of Volcanology and Seismology (Phivolcs) yesterday warned that 30 percent of medium-rise buildings and 38 to 40 percent of residential structures may be adversely affected once a 7.2-magnitude earthquake hits Metro Manila.

Phivolcs director Renato Solidum also reported in a Senate hearing that about 13 percent of high-rise buildings in the metropolis might suffer slight to heavy damage in a strong tremor.

“That’s a big percentage. Our advocacy is to educate the people. What will happen if rains and earthquake occur altogether at one time, and if these will be coupled with landslides? It will be more difficult to respond,” Solidum explained.

He stressed the need for a stricter implementation of the building code, and an evacuation plan if an earthquake occurs.

“We should be prepared by making our buildings formidable in quakes. We should have evacuation plans. There should also be preparedness for response,” Solidum said.

He said, however, that the probability of a strong earthquake happening in the country is “close to zero” because there is no fault activity at present.

“It’s locked. It’s not moving but it’s classified as active because it moved before,” he added.

Citing historical and geological data, Solidum said the west valley fault line last moved 200 years ago, with intervals of 200, 400, and 600 years. It moved four times in 1,400 years.

“The last movement, we think was 200 years ago. So if we use the lower interval there’s a possibility of a strong quake. But it’s not going to be soon as we’re monitoring the fault. It’s locked,” he said.

Solidum said there are about 1.3-million houses in the path of the so-called west valley fault line, which lies from the Sierra Madre in Bualac passing through Marikina City, some portions of Cainta and Pasig, Alabang and areas in Laguna including Sta. Rosa, San Pedro and Carmona.

The Department of Public Works and Highways (DPWH) said it has been implementing earthquake-related measures in the construction of buildings.

“We have already revised our parameters to ensure stronger design of structures. The DPWH has undertaken the measures similar in the earthquake proof designs of San Francisco, California,” said DPWH Undersecretary Manuel Bonoan.

‘No worry’ about San Roque Dam

A ranking official of the National Power Corp. (Napocor) allayed fears over reports that the San Roque Dam may cause further damage to lives and property because it is located in a fault line.

“The San Manuel segment will not in any way affect the San Roque Dam… The danger from the rupture is not there. There is no worry there,” said Napocor vice president Danillo Sedilla.

Sedilla said the engineers who surveyed the building site of the dam in the 1970s already noted the fault line.

– With Jess Diaz, Aurea Calica

“The engineering geology which was made in March 1979 was part of the information given to the proponent for the San Roque project,” Sedilla told the Senate committee.

“The info on these faults were already incorporated, so in the construction and design made by the San Roque power (plant) they did not rely only on the information provided by the NPC,” he said.

Phase-out multi-purpose dams

Butil party-list Rep. Leonila Chavez yesterday said the government should gradually phase out giant multi-purpose dams in Luzon to save low-lying communities from flooding.

Besides endangering life and property, Chavez said these dams that generate electricity and irrigate fields are already obsolete and costly to maintain and operate.

In place of these ageing dams, alternative water infrastructure like the small water catchment basis or collectors can be constructed.

She pointed out that other nations are now reviewing their multi-purpose dams because they cause destructive floods during the rainy season.

“Even the Three Gorges Dam in China, the largest of its kind in the world, is being questioned on environmental, social and economic grounds,” she added.

Chavez said dams are useless during the dry season “because there are not enough watershed areas to support them.”

She said despite the operation of at least six dams in Luzon —Binga and Ambuklao in Benguet, San Roque in Pangasinan, Casecnan and Pantabangan in Nueva Ecija, and Angat in Bulacan —the total area of irrigated farmland has remained less than a million hectares,

“Multi-purpose dams are a 19th century creation. They should have no place in the 21st century,” she said.

Senators propose creation of fact-finding commission

Fifteen senators are seeking the creation of a national commission to formulate measures that will determine the course of rehabilitation in the country after the deadly onslaught of typhoons Ondoy and Pepeng.

The proposed commission will also investigate causes of the heavy flooding in Northern Luzon. The commission will be given six months to conduct the probe.

Senate Bill 3480, filed by Sen. Francis Pangilinan, will determine the cost of reconstruction, raise the needed funds, decide which projects to prioritize, oversee implementation and serve as a clearinghouse for donations.

The bill is supported by Senate President Juan Ponce Enrile, Senate President Pro Tempore Jinggoy Estrada, Senate Majority Leader Juan Miguel Zubiri, Senate Minority Leader Aquilino Pimentel Jr., Senators Alan Peter Cayetano, Jamby Madrigal, Loren Legarda, Manuel Roxas II, Benigno Aquino III, Gregorio Honasan, Edgardo Angara, Richard Gordon, Panfilo Lacson and Francis Escudero.– with Jess Diaz, Aurea Calica