Unusual cluster of earthquakes detected in Zamboanga del Norte

ZAMBOANGA CITY, ZAMBOANGA DEL NORTE — The Philippine Institute of Volcanology and Seismology (Phivolcs) detected an unusual number of tremors in Siocon, Zamboanga del Norte, on Monday.

Engr. Allan Rommel Labayog, regional field officer of Phivolcs, Zamboanga City satellite office, said at least seven quakes with magnitudes ranging from a low of 1.5 to a high of 4.05 had been monitored in Siocon town between 2:44 a.m. to 11:23 a.m. on January 3.

He said this was the first time that tremors were detected seven times in Siocon. “Six events took place at dawn of January 3 and another one at noontime. Two events took place just offshore of Siocon town while the five events were inland,” Labayog said.

The series of earthquakes started with a magnitude 2.7 at 2:44 a.m.; followed by a magnitude 3.6 at 2:46 a.m.; a 1.7 magnitude at 3:28 a.m.; a 1.5 magnitude at 3:47 a.m.; a 1.6 magnitude at 4:05; and another 1.5 magnitude at 4:05 a.m.

At 11:23 a.m. Monday, a magnitude 2.9 quake with a depth of 80 kilometers, was detected a few kilometers southeast of Siocon, Labayog noted.

“At that magnitude, we don’t expect any destruction. They’re not even felt in other areas of the Western Mindanao region but it is not conclusive, we still have to be prepared for bigger events in the future. We should be prepared if a bigger event will occur,” Labayog said.

He said all the movements in Western Mindanao originated from the Sulu trench, located near the area of Siocon. “It is offshore,” he said. “Aside from the quake, it is also capable of a tsunami if it would be a big magnitude event.”

Historically, on September 21, 1897, a powerful 7.5 magnitude quake with a depth of 640.6 kilometers struck the areas of Siocon, Baliguian, and other parts of the Zamboanga Peninsula.

“That is why the level of preparedness in those areas is very high,” he said. “We hope Zamboanga City will also exercise the same preparedness because of the proximity of Siocon and Baliguian towns to Zamboanga City.”

He said that in 2021, over a hundred earthquakes were monitored in the Zamboanga Peninsula region. Julie Alipala, Inquirer Mindanao