PHIVOLCS monitoring possible magnitude 8 quake

PHIVOLCS on Tuesday said the occurrence of a magnitude 8 earthquake is a possibility following the earthquake swarms that came after last Friday's magnitude-5.5 earthquake in General Luna, Surigao Del Norte.

"Puwede pong maliliit na lindol lamang at puwedeng dumiretso sa malalaki," PHIVOLCS director Renato Solidum said in a phone interview on Unang Balita.

"Ang sinabi namin ang pagdating sa mga trenches, 'yung segment offshore ng Surigao provinces ay may kakayahan magdulot ng magnitude 8 na earthquake. Matagal na po naming sinasabi yan,"

However, it is also possible that only "moderate" earthquakes will take place, Solidum said.

"Pero posible din naman na 'yung mga maliliit na paglindol o moderate size na earthquake ay hanggang doon na lamang," he said.

Solidum said the period in which the earthquake will hit a certain place cannot be detected, although PHIVOLCS can detect its magnitude or the energy released by an earthquake at the focus.

"'Yung oras kung kailan mangyayari ang malakas na lindol, hindi masasabi. Pero puwede nating matantsa kung ano ang magnitude ng bawat fault na puwedeng ipakilos ng lindol," Solidum said.

Due to this, Solidum advised residents in the eastern section of the country to be prepared and assess their tsunami preparedness measures.

According to Solidum, earthquake swarm differs from an aftershock as the latter occurs after a bigger earthquake.

"Ang earthquake swarm po ay sunod-sunod na paglindol na walang distinct na  malaking earthquake. 'Yun po ay marami at kadalasan ay pare-pareho lang ng magnitude," Solidum said.

"Ang aftershock talagang may distinct na malaking earthquake at talagang sumusunod na mga lindol ay maliliit na lang," he added.

In its afternoon bulletin, PHIVOLCS said a total of 728 earthquake events with magnitudes ranging between 1.5 to 5.5 have been recorded in the same vicinity of Surigao del Norte as of 5 a.m. Tuesday.

It attributed these seismic events to the continued subduction of the Philippine Sea Plate along the Philippine Trench.

PHIVOLCS said two scenarios can be expected from the current earthquake activity, either "continue with present activity and eventually wane in the next few days" or "culminate to a larger earthquake" as warned by Solidum.

PHIVOLCS reiterated its warning to residents in the area to take preparedness measures, follow verified information, and constantly monitor updates from the agency.

The earthquake in Surigao Del Norte was tectonic in origin and had an 11-kilometer depth of focus. The epicenter was recorded 70 kilometers southeast of General Luna town. —Anna Felicia Bajoa and Joseph Tristan Roxas/KBK/RSJ, GMA News