MANILA - Millions of people across the country, including those in the National Capital Region are exposed to the threat of tsunamis, and local communities must continue preparing for this hazard, the Philippine Institute of Volcanology and Seismology (Phivolcs) said Thursday.

“The total population exposed to tsunami would be close to 14 million but they will not be affected the same time. It would depend on where the tsunami would occur,” Phivolcs chief Renato Solidum Jr. said.

Based on Philvolcs' hazard assessment and simulation in the Philippines, the prone population in NCR would be around 2.4 million. This is followed by Region VII with 1.6 million, Region VI with 1.2 million and Region IV-1 with around 1 million.

“Tsunamis in the Philippines can move very fast simply because the trenches are closer to our shoreline. Because of this restriction, we need to be sure that people are ready so that if ever there are signs to a possible tsunami, they need to react right away,” said Solidum.

Solidum was guest speaker at the World Tsunami Awareness Day InfoSentro sa PHIVOLCS virtual press conference on Thursday where he discussed the importance of using science, technology, and innovations in helping communities prepare for tsunamis.

“The World Tsunami Awareness Day is a very important initiative globally to educate the public about the hazards of tsunami, but more importantly, how to prepare for it,” said Solidum.

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He said more communities need to be trained to prepare for the disaster.

“This preparedness in some towns in eastern Philippines was tested when super typhoon Yolanda came,” he said.

Prior to Yolanda, whose storm surge left 6,000 people dead, Phivolcs has been going around eastern Philippines because many coastal towns there are exposed to the threat of a large tsunami.

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“Tsunami and storm surges are very similar. But storm surges, when you respond to it, you also have to worry about the strong winds,” he said.

The COVID-19 pandemic is another setback for them as they could not go down to communities to talk to the people.

However, the pandemic has resulted in more people actually listening to them with the help of social media platforms.

“We reach more people in terms of information campaign. We hope local government disaster mangers would be able to do now the actual preparedness at the community level,” he said.

Understanding tsunamis

Tsunamis can be small or large waves generated by an earthquake event, submarine landslides, volcanic activity, or meteor impact.

“It can drown people, devastate agricultural land near the shore. This would carry big things like ships and boulders that could impact people and destroy houses,” he said.

In 1976, a magnitude 8.1 quake in the Moro Gulf triggered a tsunami as high as 9 meters. Solidum said the first wave arrived at the coastline within 2 to 5 minutes after the temblor and devastated southwestern Mindanao.

“In 1994, a magnitude 7.4 earthquake occurred in Mindoro and most likely triggered a submarine landslide that caused a tsunami 5 minutes after the earthquake and the height of the tsunami was as high as 8 meters,” he said.

Trenches and faults are two earthquake generators that can generate tsunamis, he said.

“We have a lot of faults and trenches that generate tsunamis that is why both the eastern and western shorelines of the country are prone to large tsunamis and those in the middle, the inland coast, can still be affected by smaller tsunami waves because of fault movement or submarine landslides,” he said.

He encouraged the public to remember the “Shake, Drop, and Roar” signs of an impending tsunami and immediately seek higher or safer grounds.

“Shake” is when a strong quake is experienced. “Drop” is when seawater is observed to be receding or dropping, and “roar” is the sound of an oncoming wave.

“Our country is prone to various hazards. We have seen the devastation of super typhoon Rolly and its impact on houses because of strong winds, the flooding, and the lahar in many places,” he said.

“We need to make sure that we work together to overcome this. But most importantly, better if we are most prepared. We have science, technology, and innovation from DOST that can help in preparedness and disaster risk reduction. We need to use it but we need to share this information to the communities and the public.”

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