4.5-magnitude quake jolts Masbate

Screen grab from Phivolcs website

MANILA, Philippines—A 4.5-magnitude quake jolted Masbate province on Saturday, January 3, and was felt in nearby areas.

The Philippine Institute of Volcanology and Seismology (Phivolcs) said the quake was recorded 20 kilometers southeast of Masbate at 12:50 p.m.

In a phone interview, Phivolcs Director Renato Solidum said the quake’s epicenter was at Uson, Masbate.

Alex Baloloy, volcanologist at the Phivolcs observatory in Lignon Hill, Legazpi City, said the epicenter was 4 kilometers north of Uson with a depth of 13 kilometers.

According to Phivolcs the quake was felt at the following intensities: Intensity 5 in Masbate City; intensity 4 in Irosin, Sorsogon; intensity 3 in Baleno, Masbate; intensity 2 in Uson, Masbate, and Legazpi City, and intensity 1 in Cabid-an, Sorsogon.

Magnitude is the measurement of the energy released at the source of the earthquake while intensity quantifies the strength of shaking produced by the tremor.

Tectonic in origin, the quake was “triggered by the movement of the earth’s crust,” Baloloy said.

No damage was so far reported, he said.

Phivolcs resident volcanologist Eduardo Laguerta said the quake was not related to the restiveness of Mayon Volcano, now on alert level 2.

Aftershocks were not expected from the quake according to Phivolcs.

Magnitude 4 to 5 earthquakes are described by Phivolcs as “feeble shocks” where damage is not usually reported.

Phivolcs Seismological Observation and Earthquake Prediction Division officer in charge Ishmael Narag said the cause of Saturday’s tremor, the movement of the Philippine fault, was similar to that which triggered a magnitude 6.2 earthquake in February 2003 in Masbate.

The epicenter of the 2003 tremor was near Magcaraguit Island, 28 kilometers  east of Masbate City, and was felt in the provinces of Masbate, Bicol, Leyte, Panay, Cebu, Negros and Romblon.

Based on the Phivolcs Earthquake Intensity Scale (PEIS), intensity 5 is strong and generally felt by most people indoors and outdoors. Strong shaking and rocking is felt throughout a building where hanging objects swing violently and dining utensils clatter. Small, light and unstable objects may topple over while liquids could spill from open containers. Vehicles can be observed to rock.

Intensity 4 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 framed buildings creak. Standing motor cars may rock slightly while liquids in containers are slightly disturbed. A rumbling sound may sometimes be heard.

Intensity 3 is described as weak and is felt by people indoors, particularly those in the upper floors of buildings, and dizziness and nausea may be experienced by some. The vibration felt is similar to that of a passing light truck and suspended objects may swing moderately.

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