The Philippine Institute of Volcanology and Seismology (Phivolcs) allayed public fears on Wednesday, Dec. 6, saying that the subsequent earthquakes were not a prelude to the "Big One."

Phivolcs Director Teresito Bacolcol clarified that the "Big One" will likely be generated by the West Valley Fault, which "has nothing to do" with the Manila Trench that caused the 5.9-magnitude quake on Dec. 5.

The term Big One refers to severe and catastrophic earthquake scenarios, often referring to the worst-case scenario of a 7.2-magnitude earthquake triggered by the West Valley Fault.

"Huwag po silang mangamba dahil 'yung nangyari pong paglindol kahapon is nasa Manila Trench po and the Big One would be generated by the West Valley Fault. Magkakaiba ang earthquake sources po niyan (They do not have to worry because the earthquake that occurred yesterday is in the Manila Trench and the Big One would be generated by the West Valley Fault. There are different earthquake sources)," Bacolcol said in a Teleradyo interview.

Bacolcol noted that the West Valley Fault, which is situated in land, while the Manila Trench, which is in the ocean, are not connected.

The West Valley Fault last moved in year 1658 and the reoccurrence interval of its movement is 400 to 600 years, Phivolcs said.

Meanwhile, Bacolcol pointed out that the occurrence of successive earthquakes was a "coincidence" as the Philippines is "tectonically active."

"The Philippines is tectonically active. We have six trenches and 175 active fault segments. There is always the possibility that they occur simultaneously or successively," he said.