By Brian Campued
Two earthquakes with magnitudes 5.3 and 4.9 struck almost the same epicenter in Quezon province on Wednesday morning, the Philippine Institute of Volcanology and Seismology (Phivolcs) said.
According to its latest earthquake bulletin, Phivolcs said the magnitude 5.3 earthquake hit 42 kilometers northeast of Jomalig, while the magnitude 4.9 quake struck 38 km northeast of the same town at 7:55 a.m.
The first tremor had a depth of focus of 2 km, while the second had a 1 km depth of focus.
Following are the reported intensities:
- Intensity V – Jomalig and Polillo, Quezon
- Intensity IV – Burdeos and Panukulan, Quezon; and Santa Elena, Vinzons, and Paracale, Camarines Norte
- Intensity III – Guinayangan, Alabat, Tagkawayan, Calauag, General Nakar, Real, and Mauban, Quezon province; Quezon City; and Pateros.
- Intensity II – Atimonan, Lopez, and Gumaca, Quezon; and Basud and Gallego, Camarines Norte
- Intensity I – Caloocan City; Pasig City
Instrumental intensities:
- Intensity IV – Jose Panganiban, Camarines Norte
- Intensity III – Mauban, Guinayangan, Alabat, and General Nakar, Quezon; Daet, Camarines Norte; and Tinambac, Camarines Sur
- Intensity II – Dingalan, Aurora; Gumaca, Lopez, Mulanay, and Calauag, Quezon; Sagnay, Pasacao, and Ragay, Camarines Sur; Los Baños, Laguna; Marikina City; and Tagaytay City, Cavite
- Intensity I – Dolores and Lucban, Quezon; Calamba City, Laguna; Boac, Marinduque; Iriga City, Camarines Sur; Antipolo City and Tanay, Rizal; San Rafael and Marilao, Bulacan; Tabaco City, Albay; Pasig City; and Caloocan City
Meanwhile, the magnitude 4.9 quake resulted in the following reported intensities:
- Intensity IV – Polillo, Quezon
- Intensity III – Guinayangan, Alabat, Tagkawayan, Calauag, and Panukulan, Quezon; Makati City; and Quezon City
- Intensity II – Lopez and Gumaca, Quezon
Instrumental Intensities:
- Intensity IV – Jose Panganiban, Camarines Norte
- Intensity III – Mauban, Alabat, Guinayangan, and General Nakar, Quezon; Daet, Camarines Norte; and Tinambac, Camarines Sur
- Intensity II – Daet, Camarines Norte; Tagaytay City, Cavite; and Gumaca, Mulanay, and Calauag, Quezon
- Intensity I – San Rafael and Pandi, Bulacan; Calamba, Laguna; Antipolo City and Tanay, Rizal; Tinambac, Pasacao, and Ragay, Camarines Sur; Boac, Marinduque; Pasig City.
State seismologists said such an occurrence is called a doublet, when two earthquakes of nearly the same size occur close together in the same area.
“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,” Phivolcs said in a message to reporters.
Aftershocks are possible from the magnitude 5.3 quake, while both earthquakes are not expected to cause damages, it added. – av