Article by Arabella Balderama

The Philippine Institute of Volcanology and Seismology (PHIVOLCS) reported on Thursday morning, June 15, 2023, a magnitude 6.3 earthquake that struck Calatagan, Batangas, with effects felt in Metro Manila and nearby provinces.

The tectonic tremor had a depth of 119 kilometers, occurring at 10:19 A.M., with an epicenter recorded 15 kilometers southwest of Calatagan, Batangas.

According to PHIVOLCS Chief Teresito Bacolcol, the earthquake’s massive impact was due to the depth of its source — comparing it to how the beam of a flashlight widens and illuminates a larger area as it moves away from where it originated.

Moreover, PHIVOLCS cleared that the earthquake was possibly a result of movement in the Manila trench and that its depth caused it to be felt in mostly high- and medium-rise buildings.

The Office of Civil Defense Joint Information Center Head Diego Mariano stated that “no major damage or casualties” were reported since the ongoing assessment.

Locals, however, were advised to prepare themselves for possible aftershocks and property damage, as the earthquake is anticipated to have repercussions on its affected regions.

Intensity in Different Areas

Intensity IV, also known as “moderately strong”, was set in Manila, Mandaluyong City, Quezon City, and Valenzuela City in NCR; areas outside NCR, Malolos City, Batangas City, Ibaan, Lemery, Nasugbu, Talisay, Dasmariñas, Tagaytay, and Tanay recorded the same intensity.

Intensity III, or “weak”, was noted in NCR municipalities, such as Pateros, Las Piñas, Makati Marikina, Parañaque, and Pasig. Provinces, namely Obando in Bulacan; Laurel in Batangas; Bacoor and Imus in Cavite; San Pablo City and San Pedro City in Laguna; and San Mateo, Rizal had the same strength.

Intensity II, or “slightly felt”, was raised in Caloocan City, San Juan City, and Muntinlupa City in NCR, alongside provinces, specifically San Fernando in La Union, Alaminos and Bolinao in Pangasinan, Santa Maria in Bulacan, and Bamban in Tarlac.

Intensity I, also known as “scarcely perceptible”, was recorded in San Jose del Monte, Bulacan.

The Earthquake’s Disruptions

Various institutions, businesses, and transportation networks suffered in the earthquake’s aftermath, which led to their services being temporarily closed.

The Department of Transportation announced that the earthquake was felt at the Metro Rail Transit (MRT) Command Center in Quezon City, prompting all trains to stop at nearest stations.

To observe precautionary measures, Light Rail Transit lines one, two, and three, along with MRT line three and Philippine National Railways suspended their operations until further inspections were done by their management. Train services resumed more than an hour after the earthquake.

No tsunami warnings were issued after the earthquake. However, classes in Calatagan, Batangas were suspended as announced by Mayor Peter Oliver Palacio “to give way for the initial assessment on the effects of the earthquake on school and public buildings and other critical infrastructures.”

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