(UPDATED) A magnitude 5.4 earthquake struck off Sorsogon province in the Bicol Region at 10:37 p.m. Monday, Phivolcs said.

The undersea tremor, which was tectonic in origin, hit 37 kilometers northeast of Prieto Diaz.

It struck at a depth of 777 kilometers.

The quake was initially measured at magnitude 6.4 before Phivolcs revised its numbers.

Reported intensities:
Intensity V - Sorsogon City;
Intensity IV - Legazpi City; Virac, Catanduanes; Naga City; Catarman, Northern Samar
Intensity III -Bulusan, and Irosin, Sorsogon; Catbalogan City
Intensity II - Palo, Alangalang, Babatngon, Calubian and Dagami, Leyte

Instrumental intensities:
Intensity IV - Legazpi City
Intensity III - Sipocot, Camarines Sur; Borongan City, Eastern Samar; Palo, Leyte; Irosin, Sorsogon
Intensity II - Naval, Biliran; Jose Panganiban, Camarines Norte
Intensity I- Lopez, Quezon; Casiguran, Aurora

Phivolcs said the tremor is expected to produce aftershocks. - With reports from Gerard Lorbes and Karren Canon

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