Passing through

By Jimmy K. Laking

Gentle earthquakes

That the Davao region appears prone to earthquakes is a realization people are coming to grips with.

The latest was this 6.4 magnitude earthquake that shook the cities and provinces around the Davao Gulf before midnight on September 6, 2020. Its epicenter was located near the town of Don Marcelino in Davao Occidental.

Like a series of earthquakes that struck the same vicinity in 2019, this earthquake caused the ground to sway only to settle down shortly. The Philippine Institute of Volcanology and Seismology (Phivolcs)) ruled out widespread damage or deaths.

I believe the reality is obvious by now. The kind of earthquake that has visited the Davao region is gentle at best. Comparatively speaking, it is bereft of the destructive force that hit other parts of the Philippines during the past decades.

The plausible reason why it triggered people to move out to tents in 2019 was because of trauma and the knee-jerk reaction of authorities in the face of aftershocks felt then in Davao del Sur, North Cotabato and Davao Occidental when a series of five earthquakes, averaging 6 magnitude struck days apart of each other.

Consequently, the buildings that collapsed or the than 200 school buildings that incurred damages were of questionable integrity as local officials conceded unofficially.   

Yet taken as a whole, the situation would pale in comparison to the widespread destruction attributed to a 7.8 magnitude earthquake that struck the cities of Baguio, Dagupan and Cabanatuan on July 16, 1990. This earthquake caused the death of more than 2,000 people and destroyed road infrastructure.

In Baguio City, several of the 28 establishments that were destroyed included the 12-story Hyatt Terraces Hotel that folded to an unrecognizable pile, killing at least 50 people in the process.

The earthquake also transformed Baguio City into a ghost town as a largely migrant and a student population fled the city, trekking across eroded mountainsides, on their way to the provinces.   So great was the devastation that the city and nearby towns were sealed off from the outside by landslides, the economy at a standstill. It would take years but like the proverbial Phoenix, the three cities rebounded economically.

The 1990 earthquake was also tectonic in origin. But this was not content on just swaying the earth. This one split the ground on several places, caused the ground to jump up and down, and the more than 100 equally-destructive aftershocks made sure only the sturdily-built buildings stood firmly. Bridges gave way and the roads to Baguio City sealed off by boulders and earth.  The “resident earthquake” that is bothering the Davao region is a baby by comparison.

Yet there should be no cause for worry. Following the Building Code of the Philippines, Engr. Carlos Villaraza of the Association of Structural Engineers of the Philippines was quoted as saying that for so long as a building complies with the code, it can withstand a magnitude 8.4 earthquake regardless of its proximity to a fault line.

Ronald Paulo of the Megawide Construction Corporation added that compared to buildings in other Asian countries, structures in the Philippines are designed to be able to endure up to magnitude 8 earthquakes.

He said Filipino structural engineers are well aware that the Philippines is prone to earthquakes (being situated along the Pacific Ring of Fire) “and thus they design our buildings with this consideration in mind.”

DOST undersecretary Renato Solidum also practically said as much when interviewed in Digos City in November last year.

So if earthquakes with magnitudes ranging from 6 to 6.9 are enough to trigger the collapse of buildings, what does this suggest?  And why?  Time to call a spade a spade.

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