MANILA, Philippines ? (UPDATE) A 5.4-magnitude earthquake of tectonic origin rocked parts of Luzon, including Metro Manila on Tuesday morning, the second tremor of such magnitude in three days, the chief of the Philippine Institute of Volcanology and Seismology said.

The quake was part of an ?earthquake swarm? or series of tremors that started last Thursday, caused by the movement of the East Luzon Trough off the northeastern seaboard, Phivolcs Director Renato Solidum said.

Solidum said ?earthquake swarms? were common and could last for over a month.

The epicenter of Tuesday's earthquake was on the same location as last Sunday, 98 kilometers east of Baler town, Aurora province, with a depth of 13 kilometers, Solidum said in a phone interview.

Intensity 4 was felt in Quezon City, Manila, and Baler, intensity 3 was felt in Makati City and Dingalan town in Aurora, while intensity 2 was felt in La Trinidad town and Baguio City in the north, the Phivolcs chief said.

The tremors over these past days do not confirm rumors of a strong earthquake in the capital next week, Solidum said.

He said there was no way to predict when and where an earthquake would strike, even as scientists could estimate how much magnitude a fault was capable of producing.