A LIGHT and a moderate earthquake rocked Quezon province yesterday, the Philippine Institute of Volcanology and Seismology (Phivolcs) said.
The epicenter of the magnitude 5.3 and 4.9 earthquakes was some 42 km northeast of Jomalig town in Quezon. Both were tectonic in origin.
The magnitude 5.3 tremor (initially reported as magnitude 5.6) occurred at 7:16 a.m. and had a depth of 4 km while the magnitude 4.9 quake was recorded at 7:55 a.m. and had a depth of 1 km.
Phivolcs director Teresito Bacolcol said the 4.9 magnitude quake was not an aftershock of the first quake.
“We call it doublet… Doublet happens when two earthquakes of almost the same magnitude happen very close to each other, in the same area,” he said.
Phivolcs, in a statement, said, “Though they seem similar, they are actually separate events, not one triggering the other. This happens where faults are quite complicated, causing the stress to trigger a sequence of events.”
Bacolcol said the two quakes are not capable of generating tsunami.
“(Magnitude) 4.9 is considered as a light earthquake while (magnitude) 5.3 is considered as a moderate earthquake. To generate a tsunami, it (earthquake) to be magnitude 6.5 (or higher),” he said.
Bacolcol also said no damage is expected from the two quakes. He said damage can be expected only when an earthquake’s intensity is VI and higher.
Shaking from the 5.3 quake was felt at Intensity V in Jomalig and Polillo towns in Quezon; Intensity IV in Burdeos, Panukulan, and Patnanungan towns also in Quezon; and Paracale, Santa Elena, and Vinzons towns in Camarines Norte.
Intensity III in Alabat, Calauag, General Nakar, Guinayangan, Infanta, Mauban, Real, and Tagkawayan towns in Quezon; Capalonga, Jose Panganiban, Mercedes, and San Lorenzo Ruiz towns in Camarines Norte; and Quezon City, Taguig City, Pateros town in Metro Manila.
On the magnitude 4.9 tremor, shaking was felt at Intensity IV in Polillo town; Intensity III in Alabat, Burdeos, Calauag, General Nakar, Guinayangan, Infanta, Mauban, Panukulan, Real, and Tagkawayan towns in Quezon; Paracale, Santa Elena, and Vinzons town in Camarines Norte; and Makati City, Quezon City and Pateros town in Metro Manila.
