Samal Is. won’t protect Davao City from tsunami – Phivolcs

DAVAO CITY (MindaNews/07 August) – Samal Island won’t serve as a buffer for this city in case a tsunami occurs, an official of the Philippine Volcanology and Seismology (Phivolcs) Davao said on Friday.

Phivolcs-Davao research specialist Desiderio P. Cabanlit said that based on a simulation, the result may even be worse as water coming from behind Samal would pass through both sides of the island and form bigger waves as they converge at a certain point.

On April 15, 1984, a tsunami inundated Sigaboy, Davao Oriental after an 8.3-magnitude earthquake struck.

Cabanlit said if a quake of the same intensity occurs at sea nearby, it will only take 30 minutes for a tsunami to reach the shores of the city. He said his calculation showed the waves would be four meters high and reach 500 meters inland.

Aside from tsunami, which could happen if a strong quake occurs at sea, a tremor may cause liquefaction, fires and landslides.

A study, “Fault Distribution, Segmentation, and Earthquake Generation Potential of the Philippine Fault Zone in Eastern Mindanao,” found out that the Davao Oriental and Compostela Valley are at risk of getting hit by a strong earthquake based on the recurrence time.

In Davao Oriental, the study singled out the popular tourist destination Mati, the provincial capital.

“There’s a big possibility that the next strong earthquake will hit in these areas,” Cabanlit said in Cebuano.

The two provinces lie along a 320-kilometer fault line that stretches from Surigao to Compostela Valley. This fault line is part of a 1,200-km Philippine fault zone, from Luzon down to Mindanao.

Cabanlit said the fault line cannot be seen from plain view that a pool of specialists from Phivolcs had to do trenching since 2007 to know how many cracks there are beneath the surface.

These cracks, some of which are left unrecorded over time, allow the scientists to establish time intervals between the movements of the fault.

“With the trending, we can estimate when the next strong quake is happening,” he said.

A 7.2-magnitude quake jolted Monkayo in 1893 and it has not recurred since. Major quakes have recurrence time.

The West Valley Marikina Fault, which cuts across Metro Manila, can trigger landslides once it moves and results in the “Big One”, a 7-magnitude quake that is calculated to kill thousands of people.

At an average, Davao Region experiences five unfelt earthquakes a day.

“These only prove that we have an active fault line,” Cabanlit said.

Phivolcs has put up unmanned stations to monitor the earthquakes. These are located in Don Marcelino in Davao del Sur, Valencia City in Bukidnon, and Mati in Davao Oriental. (Antonio L. ColinaIV/MindaNews)