Last of two parts
There are now more sophisticated methods available to detect fault lines even before earthquakes occur to reveal the lines. Laser Imaging Detection and Ranging (Lidar) is one of the newest available, with a laser beam projected from an airplane detailing images of the ground surface. Using advanced software, Lidar is able to bypass vegetation to reveal the ground beneath in a computer-generated image, which can be used to identify the active faults.
Minimizing the damage to be caused by future temblors can be accomplished with the new data, which serves as a guide as to where to build new structures and where to reinforce existing ones.
A study conducted by Phivolcs in cooperation with the Japan International Cooperation Agency (Jica) found that 13 percent of residential buildings and 10 percent of mid-rise buildings in Metro Manila will be severely damaged, while only two percent of high-rises to be affected.
The Jica-funded study is worth noting because like Japan, the country is quake-prone. High standards for building materials are required. For instance, it is illegal to produce reinforcement bars from wire rods in the Philippines since they have significantly less tensile strength than bars produced from steel billets.
Government regulators check local steel manufacturers to make sure the bars are produced from high-grade billets. Regular monitoring of finished products ensure that bars weigh exactly as prescribed.
The proliferation of substandard steel bars in Bohol and Cebu discovered after last year’s killer quake is very likely due to rampant smuggling of steel products. For years, the Cebu port has been notorious as entry point for smuggled steel products coming from obsolete steel plants in China that had been closed long ago.
Recall that when a strong quake rocked central China a few years ago, entire cities were flattened. The culprit was poor enforcement of engineering standards and the use of inferior steel reinforcement bars. Also in China, a newly completed but still unoccupied high-rise apartment building collapsed like a house of cards while surrounding buildings remained standing.
The large volumes of smuggled steel products that have entered the Cebu port did not only evade payment of taxes and duties. They also avoided technical inspection on product quality. The smuggled steel products were sold at marginally lower prices—but pose immense danger to public safety.
At least it can be said that there are few high-rises in Cebu and none in Bohol. But what of Metro Manila, which is seeing an unprecedented number of high-rise, mostly residential condominiums being built of late?
Phivolcs director Solidum says the new towers may actually be safer.
“An analogy that I use is that if you are angry, it will be easy for you to shake the small and thin persons rather than the tall and heavy ones,” he told The Manila Times. Greater damage will therefore occur with smaller and shorter buildings such as residential houses instead of the towering condos. But only if the latter used materials of the highest standards.
When the “Big One” finally hits the National Capital Region, major damage will occur to such landmarks as the Ateneo de Manila University and the University of the Philippines (built in 1908) because of their proximity to the West Valley fault line.
Elite residential enclaves such as Forbes Park and Dasmariñas Village in Makati, Wack Wack village in Mandaluyong, Valle Verde in Pasig, and Ayala Alabang village in Muntinlupa will not be spared.
White Plains, La Vista, Loyola Grand Villas and Green Meadows in Quezon City; Greenhills in San Juan; and Woodridge Heights in Marikina were also erected parallel to the fault.
Slum areas such as Payatas and Bagong Silangan, also in QC, will also be affected.
Also exposed to hazard are the business and commercial districts of Ortigas Center in Pasig, the Makati Central Business District, Eastwood in QC, and Fort Bonifacio Global City occupying parts of Taguig as well as Makati.
Even the big private hospitals such as Medical City and Saint Lukes hospital will not be able to care for the victims of the expected quake as they, too, are in harm’s way.
Since the fault is already densely populated and existing buildings cannot be relocated, Solidum said he hopes that all local government units are now implementing their recommendation of a five-meter buffer zone on both sides of the fault for newer developments.
“The main issue is how to make sure buildings and houses are made safe,” he said. “In an earthquake—because it happens so suddenly and no one knows what will happen—you have to make sure houses and buildings are safe and will not collapse during the shaking, and you have time to get out.”
Owners of existing structures which were built prior to 2001 when the National Structural Code of the Phils. was enacted can only find out for themselves if they are located in the danger zones.
If leaving or abandoning the building is not an option, then the only choice left is to retrofit using materials of the highest standards.
Recently, a 4.2-magnitude earthquake off Pangasinan created slight tremor in Metro Manila all way through Lucban, Quezon. It was followed by another 4.3 earthquake in Antique at intensity II and III at certain areas of the Visayas.
The day after, Sarangani was shocked by a 4.8-magnitude earthquake.
After Visayas and Mindanao, could it be Metro Manila next?
According to Solidum, preparedness must involve all under a 7.2-magnitude scenario to avoid what happened in Bohol.
“What I advocate is scenario-based preparedness, meaning for such a large event one cannot do preparedness by locality only and then you combine the plan. The preparedness should include all, the region,” he said.
“We also have simulation where international search and rescue groups come in. Other local responders from different parts of the Philippines come in so that they can respond to Metro Manila,” he added.
Solidum said they have been also conducting education campaign in schools, government agencies, and even private companies or organizations to reduce the impact in working places.
“We also deal with, aside from the government, businesses because if you think about it when it comes to a major disaster our lifelines—power, water, and communication are vital, especially after major disaster,” Solidum said.
“You need to reenergize the area, give them power and more importantly we need a good supply of water. That is important for the long term,” he added.
However, the durability of houses and buildings seems to be the major problem in a disaster response.
Vulnerable buildings will lead to immobility. Unpassable roads and bridges due to intense ground shaking and liquefaction will prevent people to evacuate to safer areas.
“We need to preposition supplies, not only for food and also water, but also rescue and equipment, and also people because of this scenario. One is not expected to be able to go from one place to another,” he said.
In the wake of widespread damage caused by the Bohol quake, government should hold responsible the individuals whose job it was to prevent smuggling, check the product quality of construction materials and enforce the country’s building codes. The scale of devastation was due to failure to enforce standards. The damage to buildings is as much a measure of poor governance as it was an act of nature.
There are many to be held to account for magnifying the destructiveness of the quake that hit last year: manufacturers who deliberately produce substandard bars or make them from wire rods; manufacturers not licensed to produce reinforcement bars to begin with; importers who smuggle in inferior bars and evade product inspection; Customs personnel colluding with smugglers; retailers found in possession of substandard products and other public officials complicit in the proliferation of substandard building materials and allowing building codes to be violated.
Continued poor governance resulting in inferior structures will make the people even more vulnerable to future calamities, as what happened in Bohol and Cebu in November of 2013.
Retrofitting can save buildings even after they have been damaged, as what happened with Feati University in downtown Manila. After Feati’s main building was severely damaged by a quake some two decades ago, there were calls to demolish what appeared to be a hopelessly damaged old school. Instead, some of its engineering graduates came to the rescue by designing a retrofitting plan. Today, Feati looks none the worse for wear.
If, like Japan, all new houses and buildings were built with materials of the highest standards, there is no reason why Metro Manila or Metro Cebu cannot survive earthquakes of up to magnitude 9.
What neither metropolitan areas might not withstand would be a tsunami similar to the one that hit Japan in 2011. But that’s another natural calamity altogether.