Twin earthquakes shake parts of Bicol region

A magnitude 5.5 tectonic earthquake rattled parts of Bicol and Eastern Visayas early yesterday morning but no damage or casualties were reported, the Philippine Institute of Volcanology and Seismology (Phivolcs) said.

Phivolcs also recorded a magnitude 4.5 quake at 1:25 a.m. yesterday with its epicenter traced at 44 kms northeast of Sorsogon, and felt at Intensity 2 in Lignon Hill in Albay.

Phivolcs director Renato Solidum said the magnitude 5.5 tremor struck at 3:09 a.m. and was located some 46 kilometers northeast of Sorsogon, Sorsogon.

The quake was felt at Intensity 5 in Legazpi City, Sorsogon City and Irosin, Sorsogon.

It was also felt at Intensity 4 in Panganiban, Catanduanes and Catarman, Northern Samar; and at Intensity 3 in Lignon Hill, Albay; Naga City; Catbalogan, Western Samar; and Borongan, Eastern Samar.

Solidum said aftershocks are expected.

An aftershock is a small earthquake, usually one of several, that follows a larger one after a period of time.

Ed Laguerta, Phivolcs’ resident volcanologist in Legazpi City, said the twin quakes are considered as aftershocks of the magnitude 5.8 temblor that struck Bicol last Aug. 15.

Magnitude refers to the measure of energy of an earthquake specified on the Richter scale.

Intensity, on the other hand, is a measure of the severity of shaking and the attendant damage on the surface of the earth.

The Philippines sits on the so-called Pacific Ring of Fire where continental plates meet, causing seismic and volcanic activity.

Solidum said about 20 earthquakes hit the country every day but only a few are felt.   – Helen Flores, Cet Dematera and Celso Amo