AFTER the devastation of Bohol, no place is ever safe from an earthquake’s rage, not even the country’s capital—Manila.
According to Jeffrey Perez, supervising science and research specialist at the Philippine Institute of Volcanology and Seismology (Phivolcs), the Marikina Valley Fault—stretching along Marikina, Quezon City, Pasig and Muntinlupa, and even extending to the provinces of Bulacan and Laguna—could produce a destructive earthquake.
“The Marikina Valley Fault system is a 100-km long fault line that could cause the occurrence of an 8-magnitude earthquake, which could devastate cities,” he said.
The specialist said the depth of the earthquake’s focus and the strength of infrastructures can also define the damage an earthquake could make.
“The closer the focus of the earthquake is to the ground, the greater and more dangerous its effects could be. When the source of an earthquake is too deep, its strength diminishes as the seismic waves would take longer time to reach the surface of the ground,” Perez explained.
Engineer Juan Capuchino, city building official of Manila, said some infrastructures in the city might not be able to withstand high-intensity earthquakes due to old age.
“The concrete of old buildings gets brittle through time and the strength of its reinforcement, the steel bars, has lessened,” he said.
He added that they already advised administrators to retrofit their churches to avoid potential collapse.
“However, they cannot just renovate their churches as they still have to secure clearance from the National Heritage Commission,” Capuchino said.
To keep possible damage at mimimum, he said they regularly conduct building inspections to make sure the infrastructures would not collapse should there be an occurrence of an earthquake.
“We conduct inspection on all buildings of Manila and issued a directive instructing high-rise buildings to install a parallelograph, which will determine the movement of the ground,” Capuchino said, adding that they also study the building plans before issuing permits to make sure that the structure is strong enough to withstand earthquakes and its occupants’ safety is not compromised.
He also stressed that height restriction for buildings is only implemented in specific locations, like structures within the vicinity of the Malacañang Palace, cultural heritage sites and airport runways, noting that the height has less to do with its ability to survive a strong earthquake
“The height does not affect the strength of the infrastructure; its design is the one governing its stance and whether the best and right materials were used would always matter,” Capuchino said.
Perez echoed him, saying that a strong structure, even if it is just a few meters away from the fault line, would not be destroyed.
Preparedness is the key
According to Perez, the factors that trigger an earthquake are still unidentified, so prediction of when such calamity would strike is still not possible.
“There is still no way to predict the time and place in which earthquake would occur,” he said. “The only thing we could identify is its possible source, the active faults.”
Perez said Phivolcs reaches out to various communities to orient them about earthquakes, as well as necessary protocols to be observed regarding such disasters and produce maps which are translated to different dialects which can be easily understood by the locals.
He added that Phivolcs also warns people living near the coastline of the possible occurrence of a tsunami, which could arise when at least a 6-magnitude earthquake—which has its source 30 kilometers beneath the sea floor—occurs.
“Those living near the coast must know the three natural signs of tsunami occurrence which are strong ground shaking, the receding of water, and a roaring sound from the sea,” Perez said. “These natural signs could spare them from danger.”
He said the use of seismometers, which detect seismic waves produced by earthquakes, enables Phivolcs to issue a bulletin containing the necessary information about the earthquake and a warning on possible occurrence of aftershocks, five to 10 minutes after its incidence.
“Earthquake orientations and information dissemination could still be intensified if there will be more support from the government, which would also mean more researches, materials and equipment produced, thus, further helping more people,” Perez said. Altir Christian D. Bonganay
