Buildings designed, built properly generally safe in strong earthquakes, says engineer

Most of the high-rise structures in the National Capital Region, like condominiums and office buildings, are "generally safe" if a strong earthquake hits Metro Manila.

A magnitude 6.9 earthquake hit Bogo City in Cebu on September 30 while a magnitude 7.4 earthquake hit off the shore of Manay in Davao Oriental last week.

“I would generally say that condominium and office buildings, mostly high-rise structures, are generally safe in terms of structural design,” said Engineer Ronaldo Ison, a former president of the Association of Structural Engineers of the Philippines.

“Sa mga high-rise buildings, gumagamit na tayo ng mga sheer wall. Ito yung mga buhos ng mga pader na tumutulong para ma-resist ng mga mataas na buildings, yung mga malakas na lindol,” he added in a report on "Unang Balita,"

(In high-rise buildings, we now use shear walls. These are concrete walls that help tall buildings resist strong earthquakes.)

Ison also said high-rise buildings may be safer than low-rise structures, especially if the latter have not been inspected by building officials.

“Buildings that are designed and constructed in accordance with the code shall be generally safe.  Developers get reputable engineers to design them," Ison said.

“They are generally safe because they are designed and constructed properly," he added.

To ensure the buildings are safe against earthquakes, the public may request the building administrator or developer to provide documents proving that the building underwent necessary inspections.

According to a study of the Philippine Institute of Volcanology and Seismology (PHIVOLCS), Metropolitan Manila Development Authority, and Japan International Cooperation Agency, 40% of residential buildings in Metro Manila could collapse or be affected once the “Big One,” or the magnitude 7.2 earthquake, hits.

PHIVOLCS plans to update the data next year. –NB, GMA Integrated News