MANILA, Philippines—(UPDATE) A 5.7-magnitude earthquake struck off Legaspi City on Friday but there were no immediate reports of casualties or damage, seismologists said.

The epicenter of the quake, which hit at 6:25 p.m. (1025 GMT), was 66 kilometers (40 miles) east-southeast of the town of Legaspi, on the main Philippines island of Luzon, the US Geological Survey said.

It struck undersea at a depth of 10 kilometers, the USGS said, but no tsunami warning was issued.

Philippine government seismologists put the magnitude of the quake at 5.8.

Residents of the Bicol peninsula, on the southernmost tip of Luzon, said they noticed objects rattling but no panic among the locals.

Alex Baloloy, senior science research analyst of the Philippine Institute of Volcanology and Seismology, said the quake was tectonic in origin and not related to the increased abnormal behavior of Mayon Volcano, which spewed a 200-meter-high ash column on Sunday.

The archipelago nation, made up of more than 7,000 islands, sits on the Pacific "Ring of Fire" where continental plates collide, causing frequent seismic and volcanic activity. Ephraim Aguilar, Inquirer Southern Luzon