Views to Ponder: When earth’s underground moves

by Admin-Phmp

By Henrylito D. Tacio

I was still in high school when my mother told me about our previous experiences. “Don’t forget the past,” she said, “for it gives you some lessons on what to do in the present.”

These words of wisdom come in handy when dealing with earthquakes. It seems October is the month of earthquakes.

When I woke up this morning and checked my social media account, I read several posts about earthquakes.

In Surigao del Sur, a magnitude 5.2 earthquake with a depth of 10 kilometers shook the town of Lingig and Bislig City at around 9:20 in the evening. It was also felt in Davao de Oro, particularly in the municipalities of Monkayo, Nabunturan, New Bataan, Laak, Compostela Valley, Montevista, Maco, Mawab, and Pantukan.

Three hours later, an intense earthquake also took place in some parts of northern Luzon, including Ilocos Norte and Isabela, according to the Philippine Institute of Volcanology and Seismology (PhiVolcs). There was no power in some parts of Laoag.

It must be recalled that it was also in October in 2019 that three huge earthquakes happened in Davao Region.

On October 16, an earthquake of 6.3 magnitude with a depth of 10 kilometers. The epicenter was Columbio, a town 22 kilometers away of Tulunan, Cotabato. But it was also felt in Digos City, Davao del Sur. Three malls in Davao City were damaged.

Eighteen days later, a 6.6-magnitude earthquake rocked Mindanao again. In Davao Region, it was destructive in Davao and Digos City and two towns of Davao del Sur (Bansalan and Magsaysay). It was described as strong in Tagum City, Davao del Norte.

Before the month ends, on October 31, barangay Kisante of Makilala, North Cotabato was struck with an earthquake having a magnitude of 6.5. Among the towns affected with this earthquake in Davao del Sur were Santa Cruz, Matan-ao, Bansalan, and Digos City. After the earthquake, more than 300 aftershocks were recorded. 

In the two successive earthquakes (October 29 and 31), 24 people died, with 563 others injured. Eleven people were reported missing.

“People shouldn’t be living in certain places – on earthquake faults or on flood plains. But they do, and there are consequences,” Vaclav Smil once said.

It so happened that our beloved country, the Philippines, is situated in “The Ring of Fire.” That is how scientists call the area in the basin of the Pacific Ocean, where a large number of earthquakes and volcanic eruptions occur.

Seismologists – those earth scientists who specialized in geophysics, including earthquakes – claim about 90% of the world’s earthquakes and 81% of the world’s largest earthquakes occur along the Ring of Fire.

The Encyclopedia Britannica says about 50,000 earthquakes large enough to be noticed without the aid of instruments occur every year globally. “Of these, approximately 100 are of sufficient size to produce substantial damage if their centers are near areas of habitation. Over the centuries, they have been responsible for millions of deaths and an incalculable amount of damage to property,” it adds.

I have contacted the Department of Science and Technology (DOST) to share some information about earthquakes. One of the staff sent me a primer on it, which was published by PhiVolcs.

From the said primer, I found out that our country lies between two major tectonic plates: the Philippine Sea Plate and the Eurasian Plate.

“Philippine Sea Plate is moving towards the Philippine Archipelago at the rate of about 7 centimeters every year,” the primer explains. “The Eurasian Plate is being subducted along western side of Luzon and Mindoro at the rate of 3 centimeters per year except on Mindoro and northwest of Zamboanga where collision is taking place.”

At the intersection of the two aforementioned plates is the Philippine Fault Zone, “which decouples the northwestward motion of the Pacific with the southwestward motion of the Eurasian Plate.” Movements along other active faults are reportedly responsible for the present-day high seismicity of the Philippine archipelago.

According to PhiVolcs, at least 5 earthquakes per day occur in the country. For almost four decades now, the country has been affected by 10 earthquakes with magnitude greater than 7.0.

As such, there’s a big possibility that another destructive earthquake is in the offing. In fact, some PhiVolcs officials said that the country is now ripe for another Big One, as they call it.

“The only way to avoid disasters caused by earthquakes is to prepare for them,” wrote Maria Elena Paterno in her book Earthquake!

Karen Thompson Walker shares this thought: “Feeling earthquakes was part of growing up, and also preparing for them: doing earthquake drills, or having earthquake supplies. The looming feeling was part of my life. My experience of earthquakes has always been more the fear of them, or the possibility.”

San Francisco, a very popular city in California, United States, is prone to earthquakes, too. But still people live there. When it was hit, a certain Barbara Boxer was quoted as saying, “Those who survived the San Francisco earthquake said, ‘Thank God, I’m still alive.’ But, of course, those who died, their lives will never be the same again.” 

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