From a building called Castilla Monte near Burnham Park, Tanguilig instinctively ran along with the crowd, all the while thinking of his siblings who were left at home in Tuba, west of Baguio City.
“Sobrang gulo, lahat nagpa-panic, nag-iiyakan. Halu-halo ang mga tao at sasakyan sa daan. Akala mo katapusan na ng mundo," recalls Tanguilig, who was then 18 years old.
Amid the chaos, Tanguilig clearly remembers seeing structures along Harrison Road collapse right before his eyes. One of these buildings was the Baguio Park Hotel, which was reduced to rubble in an instant.
Two decades hence, last January 12, a magnitude-7.0 tremor hit the Caribbean nation of Haiti, the poorest country in the Western Hemisphere. Its capital, Port-au-Prince, crumbled much like Baguio City and suffered more massive losses and deaths.
“Mas malala iyong nangyari sa Haiti," Tanguilig observes. Upon seeing the devastation on television, he felt lucky to have survived the stronger magnitude-7.8 tremor that shook his hometown two decades ago.
Five-meter buffer zone
Some 300 kilometers away, Metro Manila did not suffer as much as Baguio City in 1990, but experts say its residents cannot afford to be complacent. The active Valley Fault System, more widely known as the Marikina Fault, that traverses the nation’s capital can move anytime.
The Metro Manila Impact Reduction Study conducted in 2004 by the Philippine Institute of Volcanology and Seismology (Phivolcs), the Metro Manila Development Authority (MMDA), and the Japan International Cooperation Agency (JICA) found that the capital is vulnerable to a magnitude-7.2 earthquake that may be generated by the Marikina Fault.
The study assessed Metro Manila’s preparedness and estimated that there could be 35,000 fatalities, 500 simultaneous fires in up to 98,000 buildings, and 170,000 structures may collapse in the event of strong temblors.
“If a structure is directly on top of an active fault line, then that structure will be completely destroyed," says Dr. Alfredo Mahar Lagmay of the National Institute of Geological Sciences (NIGS) at the University of the Philippines.
Adam Abinales, president of the Association of Structural Engineers of the Philippines, agrees: “The damage to be incurred by a building which happens to be standing directly on top of a fault line will be greater than that from a building farther away from it."
In metropolitan Manila, which has a population of around 10 million, the active fault traverses parts of Quezon City, Pasig, Taguig, and Pasay. Housing subdivisions, commercial centers, and several schools are found near the heavily populated fault line. (See: DepEd: School buildings to be graded for quake safety)
To pinpoint the distance of a proposed building from the fault line, the Phivolcs has developed a location map of the country’s earthquake faults, according to Ma. Mylene Villegas, Phivolcs Chief Science Research Specialist.
Phivolcs has set up a five-meter buffer zone on both sides of the fault line to guide property developers in their construction projects, Villegas said.
"Developers and design or structural engineers must consult Phivolcs to know how far an active fault is from the planned property. This is [Standard Operating Procedure] for engineers," Abinales says. [See: DPWH exec: Socialized housing units may be prone to quake damage]
However, he adds that such decisions still rest on property owners, and permits from local government units (LGUs) do not include such risks.
“Building inspections from LGUs only cover the building design, not the location," he said. “Ultimately, there will be no liability on the part of the owner. But still, the risk [from building a structure directly on top of a fault line] is there," Abinales says.
Like cooked pasta
With deaths from earthquakes often caused by the collapse of buildings, the strict observance of quality control in the construction and maintenance of structures is imperative.
“It is very difficult to build a structure that will completely resist earthquakes because of the very high amount of energy released [during earthquakes]," Lagmay says. He added that the force from a magnitude-7 tremor is equivalent to the detonation of 1,000 atomic bombs of the type that were used in Nagasaki.
Maximo Noche, an architecture professor at the University of Sto. Tomas, likens buildings to cooked pasta — the longer the pasta or the higher the building, the more flexible it becomes and "the more it will sway with forces like the wind." Similarly, the shorter the pasta (or the height of a building), the more rigid it is.
“In earthquakes around the world, low-rise buildings are damaged more often than high-rise structures," Noche says. He adds that modern high-rise buildings are more resilient to shock forces such as an earthquake.
Many high-rise structures in Metro Manila have reinforcements that allow them to "sway" along with seismic movements, and less of a solid structure standing on the ground, he says.
David Mikael Taclino
Inyu Web Development and Design
Creative Writer
0 comments:
Post a Comment