Newly discovered fault behind quakes that jolted Central Mindanao

DIGOS CITY, Philippines — Earthquakes jolted parts of Central Mindanao for the second consecutive day, although Sunday’s two tremors were relatively weak than Saturday’s.

The Philippine Institute of Volcanology and Seismology on its website said Sunday’s first earthquake that affected Kidapawan City and nearby areas was recorded at 12:13 a.m. with a magnitude of 3.1 (a minor earthquake). The 12:13 a.m. tremor was traced 26 kilometers southwest of Kidapawan City and had a depth of 20 kilometers.

At 12:37 a.m., another tremor – now occurring 17 kilometers southwest of Kidapawan City – was recorded. With a magnitude of 3.4, it was felt in the Kidapawan City at Intensity III (many people indoors would feel the shaking but not by people outside). It was shallower than the previous one at 12 kilometers.

Phivolcs said no aftershocks or damage were expected in these earthquakes, unlike the previous day’s, when 15 houses made of light materials were destroyed and more than three dozen other structures – including a chapel – were damaged in Makilala, North Cotabato.

The quakes that rocked Kidapawan City and other areas of North Cotabato, and nearby areas in Sultan Kudarat and Davao del Sur provinces were all tectonic in origin, including Saturday’s more than a dozen jolts.

Engineer Hermes Daquipa, Philvolcs field observer officer in charge, said the tremors were reported to have originated from a newly discovered fault in the Makilala-Columbio area.

“The Makilala-Colombio is not on the map of officially recognized distribution of faults and trenches of Phivolcs. This is the first time that it moved,” Daquipa explained.

According to Daquipa, the local fault system, which has no name, traverses along southwest of Barangay Luayon in Makilala, North Cotabato to the municipality of Colombio in Sultan Kudarat.

He, however, said there was no manifestation of ground cracking and upliftment. He said further scientific studies should be done on the local fault.

Earthquakes are a normal occurrence in the Philippines, which sits on the so-called Pacific Ring of Fire. Dozens of earthquakes are recorded in the country each week but others are too weak to be felt.

One of the worst earthquakes that took place in the country was the August 16, 1976 magnitude 7.9 tremor that triggered a tsunami. It killed between 5,000 and 8,000 people in the Moro Gulf region that included Cotabato City and Pagadian City.

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