The Philippine Institute of Volcanology and Seismology (Phivolcs) said the tremor was most likely triggered by movement of the Masbate segment of the Philippine fault.

Ishmael Narag, officer in charge of the Phivolcs seismological observation and earthquake prediction division, said the quake, which struck at 12:50 p.m. Saturday, had its epicenter 20 kilometers southeast of Masbate.
Narag said the tremor was at a depth of 14 km and was tectonic in origin.

It was felt at Intensity 5 in Masbate City; Intensity 4 in Irosin, Sorsogon, and San Jacinto and Ticao, Masbate; 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 the shaking produced by the tremor.

Narag said the cause of Saturday's tremor the movement of the Masbate segment of the Philippine fault also triggered the magnitude-6.2 earthquake that rattled Masbate in February 2003