Phivolcs warns of quake risk in Davao

DAVAO CITY—A powerful earthquake, possibly with a magnitude of 7, could strike this premier city and other parts of Southern Mindanao anytime, according to the Philippine Institute of Volcanology and Seismology (Phivolcs) after it discovered “several new cracks” in the ground in Mati City in Davao Oriental province and in Compostela Valley province.

The cracks were created by the movement of the 320-kilometer Surigao-Mati fault line, said Desiderio Cabanlit, Phivolcs senior science research specialist, citing findings of his agency’s team, which conducted a trenching project in the two areas.

The same fault line triggered a massive earthquake with a magnitude of 7.2 in 1893 and badly hit the now municipality of Monkayo, Cabanlit said. If a similar magnitude occurs in Monkayo again, Davao City will experience a 7.0- or 7.1-magnitude quake in less than a minute, he predicted.

‘Devastating’

“The Mati segment and the Compostela Valley segment are most likely to move in the region, which can cause an earthquake in the future,” Cabanlit said.

Cabanlit said the next 7.0-magnitude quake would possibly be devastating to such areas as Davao City and would trigger the collapse of buildings. He noted that many structures in Davao City were built on soft ground.

And if the next earthquake would occur at sea and would have a magnitude of 8.3, a tsunami could also strike, he said.

“This only proved that we have an active fault line,” the official said.

The Phivolcs team excavated several areas in Mati and Compostela Valley to find out if there were significant fault lines previously undiscovered. It found the cracks resulting from the movement of the Surigao-Mati fault line.

No quake records

“There were possibly other strong quakes that occurred due to the fault line, which had not been recorded based on the cracks we found,” Cabanlit said.

While the Phivolcs is certain that another strong tremor could occur, it was not sure when this would happen. “If we can get the time interval of previous quakes, we may be able to establish a trending and predict the possible dates the next earthquake would strike,” Cabanlit said, adding that “it can happen anytime.”

Liza Mazo, director of the Office of Civil Defense in Southern Mindanao, said that with the prediction, there was a need to come up with a study similar to the Metropolitan Manila Earthquake Impact Reduction Study.

It is important to prepare local governments in case a strong quake occurs, she said.