Jan 15, 2010

Are We Prepared for a Big Earthquake?

The 7.0-magnitude earthquake that struck Haiti a few days ago can happen in Metro Manila, according to seismologists and geologists.

The question is: Are we prepared?

It appears that we are not. Experts said preparations should begin in earnest to minimize damage to be caused by the big one.

A 7.2- predicted to hit Metro Manila could kill up to 33,000 people and injure 114,000 others if no adequate preparations were made, a study conducted from 2002 to 2004 showed.

“The big earthquake is certainly coming. The question is when. No one can tell. It can happen today, tomorrow, or next year. But certainly there will be an earthquake,” Emmanuel de Guzman, advisor for Asia Pacific of the UN International Strategy for Disaster Reduction, said last year.

The Metro Manila Earthquake Impact Reduction Study, undertaken by the Earthquakes and Megacities Initiative, also estimated that the earthquake could destroy 175,000 of the more than 1.3 million buildings in Metro Manila, cause 500 simultaneous fires, and force three million residents to flee.

In a 2008 interview, Director Renato Solidum Jr. of the Philippine Institute of Volcanology and Seismology said structures, especially residential and medium-size buildings, should be repaired and reinforced to prevent such a scenario.

Solidum said these types of structures were perceived to be less strongly built than high-rise buildings. Director Renato Solidum of the Philippine Institute of Volcanology and Seismology (Phivolcs) said “a strong earthquake can happen” in Metro Manila or anywhere in the country.

He noted that a 7.8-magnitude earthquake struck Luzon in 1990 and a 7.1-magnitude quake shook Mindoro in 1994. “It can happen again,” Solidum said.

Ismael Narag, officer in charge of the Phivolcs seismology department, also said a 7.0-magnitude earthquake hitting Metro Manila was possible because it is transected by the West Valley Fault.

“So a movement of the fault causing a 7.0-magnitude earthquake is realistic,” he said.

Both Solidum and Narag referred to the Metro Manila Earthquake Impact Reduction Study (MMEIRS) conducted by the Japan International Cooperation Agency (JICA).

Phivolcs said the West Valley Fault, located in the Marikina Valley, could generate a 7.2-magnitude quake.

Extensive damage

A 7.2-magnitude quake could damage 38 percent of residential buildings, 38 percent of buildings between 10 and 30 stories, 14 percent of buildings between 30 and 60 stories, and 30 to 35 percent of all public buildings.

The study also said the earthquake could cause 33,500 deaths, an additional 18,000 deaths from fire, and 114,000 injuries.

In addition, the temblor could damage nine bridges, cut 30 kilometers of electrical cables and 95 kilometers of communication cables.

Carlos Arcilla, director of the UP National Institute of Geological Sciences (NIGS), said earthquakes in Metro Manila could come from three main generators: the West Marikina Valley Fault, the Manila Trench that caused the Jan. 12 earthquake near Olongapo City, and the Philippine Fault System that caused the Luzon earthquake of 1990.

Arcilla said he knew of two private hospitals in the city built on top of a fault line.

“Some builders and owners don’t want to pay a geologist. But they would pay a feng shui expert,” he quipped.

Mahar Lagmay, also of the NIGS and an expert on faults, said the West Marikina Valley Fault had moved four times in the last 1,200 years in intervals of 200 to 400 years.

Due for a big one

The last movement of the fault was recorded at around 200 to 300 years ago.

“I think we are due for a big one. The strain on the fault is building up. So the probability of the fault moving and generating an earthquake is big,” Lagmay said.

As for being prepared for a big earthquake, Adelfo Briones of the Ateneo School of Government, said that the floods brought by Tropical Depression “Ondoy” was the perfect example of how bad local government units (LGUs) responded to a disaster.

“Because of Ondoy, there is some focus on LGU response and really it is more reactive than proactive. The focus is not mitigation. In Metro Manila, LGUs should look at the lay of the land and look at the geological characteristics of their locale,” he said.

Briones is working on a project on the natural disaster preparedness of LGUs.

Ill-equipped to respond

An audit-survey conducted in February 2009 found that a majority of LGUs were not ready to deal with earthquakes and other natural disasters, he said.

“We found that a majority of LGUs are ill-equipped to respond to disasters. There are some good policies and projects, but these are just islands. I’m not saying there are no efforts to mitigate, but the reality on the ground is different. We are a disaster-prone country, so we need to focus on this,” Briones told the Inquirer.

The survey included the skills and training of the LGU disaster-response staff, equipment and even advocacy or information dissemination.

Structural audit

For earthquake mitigation, Briones advocated taking a look at the buildings in a locale.

“How have the laws related to building structure been implemented? That is the big question,” he said.

New buildings have been structurally reinforced, according to Narag. “But I don’t know about the older buildings and some residential houses not built by real estate developers. All the earthquake drills will be useless if the building isn’t stable.”

Architect and urban planner Felino “Jun” Palafox has called for the conduct of a “structural audit” of all private and public buildings to determine their structural integrity.

“New high-rises should be safer because of the strict building permits. I am more concerned with government buildings like public schools and hospitals where shortcuts to getting permits are common due to corruption,” Palafox said.

Building codes

Arcilla said current building codes were “fairly good, if you follow them.”

“Let’s just hope there were no shortcuts taken, and hope for the best,” he said.

Arcilla added that tall buildings built after 1968 “have not been tested by a strong earthquake.”

He pushed for a review of building codes just to be sure but added that the “issue is implementation.”

Binondo, reclaimed areas

Arcilla said tall buildings in the Binondo area could be in danger because of its clay bedrock. “It was swampy before and the bedrock could be prone to liquefaction.”

Tall buildings in reclaimed areas may also be in danger because “the filling can amplify seismic waves more than solid bedrock,” he said.

Solidum said the best earthquake mitigation was “sound engineering practices. When there is a rupture in the ground, don’t build on top of it.”

Earthquake preparedness

At the same time, Solidum said the Phivolcs was active in promoting earthquake preparedness to the public, including making guidelines, providing engineers with data on faults, hazard-mapping, and lectures to schools and other institutions.

“Of course we cannot be 100-percent prepared. Hazard assessments have not changed since the 2004 study. But risk assessment can change since there could be more people coming into areas previously identified as hazardous. This is a continuing issue,” he said.

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