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Living on a Fault Line: Manila in a 7.2 Earthquake

After the death and destruction of Yolanda, we can’t help but share the pain of Nepal, where the death toll is already over 7,000 and counting—something we are already all-too-familiar with. More than seven million people have been affected, which, in such a small country, amounts to over a quarter of the whole population. In some districts, over 90 per cent of the homes have been destroyed.

The US Geological Survey has now upgraded the Nepal earthquake to magnitude 7.8 on the Richter scale, the same magnitude as the Baguio earthquake of 1990, in which over 1,600 Filipinos died. 

The collapse of the Hyatt Terraces in the wake of the Baguio earthquake of July, 1990. Photo from CNN

Post-Yolanda, it’s natural that our disaster response focuses on typhoons. After all, we get about twenty-two of them a year. But of all natural disasters—earthquakes, typhoons, droughts, floods, tsunamis, and volcanic eruptions—far and away, earthquakes pose the greatest threat to life, property and the economy itself.

We’re no stranger to earthquakes—Spanish records go back as far as the damage to Manila Cathedral in 1600—but much has changed across four centuries. An ominous change has been burgeoning megacities—cities with populations of 10 million and above. The Metro Manila area is home to over 25 million and Manila is one of the most densely populated places in the world.

Recent improvements in building and zoning laws and construction methods help. In both the LA earthquake of 1994 (the Northridge Earthquake) and the San Francisco earthquake of 1989 (the Loma Prieta Earthquake)—which were 7.5 and 6.9 on the Richter scale, respectively—fewer than 100 fatalities were officially reported in each.

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Asian cities fare much worse. Modern building techniques and zoning can only do so much in the centuries-old cities of Asia. And even the most cursory look at urban earthquake fatalities shows,the more poor people a city hosts, the higher its death toll.

What is the state of our megacity’s preparation? According to Metro Manila Development Authority Chair Francis Tolentino, the metropolitan area is only 50% prepared to face a 7.2-magnitude earthquake. Architect Jun Palafox shares the assessment that Metro Manila is not ready for a mega-quake. (For reference, 7.2 was the magnitude of the recent Bohol quake—the 1968 Ruby Towers earthquake was 7.3.) 

Ruby Towers ruins Photo, Ward Thompson

Philippine Institute of Volcanology and Seismology (PHIVOLCS) Director Dr. Renato Solidum, Jr. says that,if an earthquake comparable to that of Nepal hits the West Valley Fault of Metro Manila, the result would be catastrophic indeed: 34,000 deaths and 1,144,000 injuries. Deaths would increase to 36,000 if the earthquake occurred during the night. And earthquake-related fires would add 18,000 additional fatalities,mainly in areas where wood is a primary building material—such as older post-war neighborhoods and communities along the coast and Pasig River.

Across our entire 1,500 square-kilometer expanded urbanized area,we stand to see unimaginable levels of loss in terms of human life and property in case of a major earthquake.

Solidum’s estimates of structural damage include more than 88 million square meters of floor area collapsing into rubble, and more than 172 million additional square meters suffering slight to extensive damage. Palafox estimates that 20 percent of the structures in Metro Manila would collapse. The Japan International Cooperation Agency (JICA), in coordination with PHIVOLCS and the MMDA, estimated that 40 percent of our residential buildings would be destroyed in a 7.2-magnitude earthquake scenario.

With so much at stake, why are we so vulnerable? What should we expect and prepare for and what preparations are being made?

Metro Manila is prone to earthquakes because it is surrounded by active faults—including the Marikina Valley Fault System (the West Valley and East Valley Faults)—which some of us live right on top of.More distant tectonic instabilities, including the Philippine Faults, Lubang Faults, Manila Trench and Casiguran Faults, are a threat as well.

Metro Manila can be affected by earthquakes with epicenters as far away as Nueva Ecija and Quezon;the 7.3 Ruby Towers earthquake’s epicenter was in Casiguran, Aurora, nearly 400 kilometers from Manila.

As the center of governmental, financial, commercial, and social activities, a strong earthquake in Metro Manila will adversely affect the entire nation.

In 2004, PHIVOLCS, in collaboration with MMDA and JICA, released an Earthquake Impact Reduction Study for Metro Manila detailing the earthquake damage scenario for Metro Manila, as well as a Master Plan for a safer Metro Manila for earthquake impact. The findings and recommendations of the study are now incorporated in the Philippine Development Plan.

It recommends promoting research and development of disaster prevention technology; building a capable disaster response staff at every level,national to community; and more modern equipment for disaster management agencies. It suggests that existing buildings should be reinforced and strengthened to reduce loss of life.

The study points out that developments in building structures and materials should be utilized and stressed the need for improved building codes and the development of design standards for the cost-effective construction of low-cost housing.

Lastly, the study urged mitigation of death and destruction in fire-prone areas; particularly that existing structures in severe damage estimation areas should be improved through re-development of land use,with buildings constructed for higher earthquake resistance and use of fireproof materials. Urban redevelopment also calls for more well-located open spaces and wider roadways.

The MMDA identifies four major evacuation centers for Metro Manila residents: Veterans Golf Course, the Intramuros Golf Course, the WackWack Golf Course, and the Villamor Golf Course.

There’s no denying that it is well-enforced building codes and zoning laws—coupled with how recently the cities were built—that makes the difference in earthquake fatalities on the California side and the Asian side of the Pacific Rim. Manila was a world city centuries before San Francisco or Los Angeles were even on the map.

Though only representing a small percentage of our residential and commercial space, construction industry sources say their new buildings—mushrooming throughout the Metro—are built to withstand an 8.2 magnitude quake. But remember: most of the more than 200 deaths in the 1968 earthquake were attributed to non-compliance with building codes in the construction of the Ruby Towers Apartment building alone. A single violation can cost many lives.

Zoning, on the other hand, is more honored as an abstract principle than as an actual practice here—a reality that will come back to haunt our post-earthquake disaster response.

This is what we need to grasp: the East and West Valley Faults—which have moved four times in the past 1,400 years at intervals of 400 to 600 years—run along either side of the Marikina River and cross under the Pasig River at a right angle. There is no guarantee that any major bridge will survive a major earthquake.Even then, there’s no way to guess in advance which bridge might survive.

Within Manila, transportation as we know it will likely cease to exist, isolating whole sections of the city. Along with the bridges, the flyovers and underpasses of our main roads will sever many links; main secondary roads are often lined with street-side low-rise buildings and/or new high-rise condos. A single building collapse can block any street with tons of rubble.

Fires will burn unabated because fire trucks are unable to reach them. Not to mention broken water mains and destroyed pump stations rendering most fire-fighting impossible anyway. Fire department tankers will be needed to deliver drinking water to survivors. Electricity? Gas and diesel generators only—for as long as the fuel lasts. And the refugees will be many. As we see now in Nepal, many will be unable to return to even still-standing homes, for fear of after-shocks and weakened structures.

I’m not writing this as a tale of dystopian horror. I’m simply emphasizing that earthquake response is worth paying attention to.

The 2004 Earthquake Impact Reduction Study was a landmark achievement in terms of earthquake preparedness, but its implementation is far from complete. Everyone, including Tolentino and Palafox,would like to see more detailed earthquake assessments made.

Palafox recommends a structural audit of buildings,prioritizing government structures and low- and medium-rise residential structures.He suggests that constructions should provide their own earthquake analysis from start to finish, and, for older buildings, structural retrofitting and reinforcement.

The Department of Public Works and Highways (DPWH) inspected 1,100 buildings in the National Capital Region (NCR), including public buildings, schools, hospitals, and housing projects. Their findings are the buildings “do not need much repair.”

Tolentino has the MMDA strengthening vital bridge structures—the Ayala Bridge is expected to re-open by June 11—and turning its attention toward the assessment of elevated road structures, like the Magallanes Interchange.

DPWH reports that the Ayala, Jesus, and Osmeña Bridges need retrofitting. Noting also that the MRT and Skyway—relatively new infrastructure—are compliant with building codes, while LRT line 1 and 2 are both “at par” with the code. But even the most modern infrastructure will require engineering study in addition to repair before returning to full function.

Solidum at PHIVOLCS reminds us that local government officials should not only identify community hazards, but also the potential damage and loss in their area. In particular, they should estimate how many people may die or be injured and should also determine if there would be water supply, electricity, and communication lines. It is also important to know if hospitals, ports, and city halls would still be standing and able to operate.

Besides producing education and communication materials for communities, schools, and businesses, PHIVOLCS has a very informative website [https://www.phivolcs.dost.gov.ph]. For families, the Department of Science and Technology recommends “How Safe is my House?,” a six page earthquake-safety self-check for houses made of concrete hollow blocks,advising improvements to make family homes safer.

Earthquakes are democratic disasters. They literally level social hierarchy and plunge everyone into the radical commonality of a shared catastrophe. A major earthquake can turn even the finest home into a place you feel lucky to escape from with your life. Still, it is the poor who, already with very little, stand to lose the most insofar as they are the least protected. But those who can and do provide for themselves in advance—and who put wise plans into action—will free up rescue and relief for wherever it’s most needed. Thus the need for continued preparedness and vigilance not only on the part of the government, but also on each and every individual to mitigate the destructive consequences of what could possibly be the mother of all earthquakes. 

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