3 temblors strike, one an aftershock of Bohol quake

MANILA, Philippines—Three earthquakes—of 4- and 5-magnitudes—hit parts of Southern Luzon and Central Visayas hours apart on Saturday.

The Philippine Institute of Volcanology and Seismology (Phivolcs) said the magnitude-4 tremor that jolted Bohol, which is part of Central Visayas, was an aftershock of the Oct. 15, 2013, 7.2-magnitude earthquake that devastated the province and other parts of the region.

According to senior science research specialist Vilma Hernandez of the Phivolcs Seismological Observation and Earthquake Prediction Division, a 5.3 -magnitude earthquake shook portions of Southern Luzon and was slightly felt in Metro Manila at 1:09 p.m. on Saturday.

Hernandez said the tremor’s epicenter was 19 kilometers northwest of Calatagan, Batangas and had a depth of 118 km and was caused by the movement of the Manila Trench.

As a result of the temblor, Intensity III was felt in Paluan, Oriental Mindoro; Intensity II in Quezon City, and Intensity I in Puerto Galera, Mindoro.

At 5:56 a.m. on Saturday, a 4.1-magnitude earthquake jolted the Bicol region with its epicenter 35 km southeast of Virac, Catanduanes.

The temblor had a depth of 24 km and was tectonic in origin, caused by the movement of a local fault.

Intensity III was felt in Legazpi and Sorsogon cities while Intensity II was felt in Lignon Hill and in Virac, Catanduanes.

Around two hours later, at 8:02 a.m., Hernandez said the 4-magnitude earthquake shook the Central Visayas, the epicenter of which was 3 km northwest of Antequera, Bohol.

The aftershock of the 2013 earthquake had a depth of 4 km, and was triggered by the movement of the North Bohol fault, the Phivolcs specialist said.

The epicenter of the 2013 7.2-magnitude earthquake was 6 km southwest of Sagbayan town and devastated Central Visayas, particularly Bohol and Cebu, killing more than 200 persons and destroying over 14,000 structures. The tremor was felt as far as Mindanao.

Hernandez explained that the 7.2-magnitude quake that happened more than a year ago still registers aftershocks in the area although not as frequently or as discernibly.

As a result of yesterday’s earthquake, Intensity IV was felt in Antequera, Bohol; Intensity III in Tagbilaran City and Loay town in Bohol, and Intensity II in Cebu City.

Four to 5-magnitude earthquakes are described by Phivolcs as “feeble shocks” where damage is not usually reported.

Based on the Phivolcs Earthquake Intensity Scale (PEIS), Intensity IV is moderately strong and may be felt by some people indoors and outdoors. The vibration felt is similar to that of a passing heavy truck and hanging objects swing considerably.

Dinner plates, glasses, windows and doors rattle while floors and walls of wood-frame buildings creak. Standing motor cars may rock slightly while liquid in containers are slightly disturbed. A rumbling sound may sometimes be heard.