Phivolcs: Movement in PH trench caused 7.4-magnitude quake in Hinatuan

People evacuate following an earthquake, in Hinatuan, Surigao del Sur, Philippines December 2, 2023. Hinatuan LGU/Handout via REUTERS

MANILA, Philippines — The magnitude 7.4 earthquake that happened off the coast of Hinatuan in Surigao del Sur on Saturday was caused by movements in the Philippine trench, said Philippine Institute of Volcanology and Seismology (Phivolcs) Director Teresito Bacolcol on Sunday.

The quake happened at 10:37 p.m. on Saturday, December 2.

The state seismologist raised a tsunami alert following the quake but took it down early Sunday.

READ: Phivolcs: Surigao del Sur quake at 7.4-magnitude, aftershocks recorded

“‘Yung trench na gumalaw kagabi ay Philippine trench. May mga historical events na rin po tayo rito, and in fact in 1921, mayroon tayong magnitude 7.5 earthquake and it produced a tsunami,” said Bacolcol.

(The trench that moved last night was the Philippine trench. We also have historical events here, and in fact, in 1921, we had a magnitude-7.5 earthquake and it produced a tsunami.)

READ: PH lifts tsunami alert after strong earthquake in Surigao del Sur

He added that a total of 659 aftershocks were already detected and it is still expected to happen a few days or weeks from the time of the main shock.

READ: Magnitude 6.9 quake shakes Surigao del Sur; Phivolcs issues tsunami alert

Bacolcol assured that the aftershocks would not be stronger than the earthquake itself.

It was also not the strongest one that hit Mindanao, the Phivolcs official added.

Bacolcol further clarified that the temblor was not an “earthquake swarm” and had no effect on the West Valley fault.

It was also not related to the magnitude 6.8 quake that hit Davao Occidental on November 17 and was not caused by climate change.