There is no threat of tsunami following a 6.3 magnitude earthquake that jolted Calatagan, Batangas on Christmas Day, according to Department of Science and Technology (DOST) Undersecretary Renato Solidum Jr., who is also the director of the Philippine Institute of Volcanology and Seismology (PHIVOLCS).
The earthquake, which is tectonic in origin, is not also related to any significant change of monitoring parameters suggesting renewed magmatic activity in Taal Volcano.
“Kapag ganito po kalalim ang lindol usually ito po ay pagsutsot ng West Philippines Sea sa Manila Trench,” Solidum said in an interview aired over DZBB Super Radyo.
Intensity IV or "moderately strong" shaking was felt in Lemery and Malvar, Batangas; San Pedro, Laguna; Manila City; Marikina City; Quezon City; Cainta and Antipolo City, Rizal, and Pasig City.
While Intensity III, or "weak" shaking was experienced in Caloocan City; Tanay, Rizal; San Jose Del Monte City and Plaridel, Bulacan; Gapan City, Nueva Ecija; Cabangan and Iba, Zambales; Samal, Bataan; Valenzuela City; and Malabon City.
Intensity II was reported in San Isidro, Nueva Ecija and Alaminos City, Pangasinan.
But Solidum said aside from the movement in the West Valley Fault, residents in Metro Manila, especially those who live along the coastal areas, should also prepare for shallow earthquakes or epicenters recorded in west of Mindoro or west of Zambales, as these might generate giant waves.
Explaining why some felt and the others were unaware of the earthquake, Solidum noted that tremors are obvious in areas with soft foundations.
He added that two out of four people usually feel the jolt depending when they are on the move or in stationary positions if the earthquake’s intensity is not that strong.
The PHIVOLCS chief said that there are two intensity indicators namely the reports from the field and what is observed in the locations and second by the use of instrumental intensity.
He said that PHIVOLCS has around 100 of these instruments in the country which determines the intensity of the tremor.
Solidum said the rate of having aftershocks of deeper earthquakes is less compared to tremors in deeper depths.
READ MORE: 6.3-magnitude quake hits Batangas