A 6.0-magnitude quake struck off the eastern coast of the Philippines on Saturday, the US Geological Survey said, but no tsunami warning was immediately issued.
The quake hit at 9:09 pm local time (1309 GMT) off the island of Samar, at a depth of 60 kilometres (38 miles) around 100 kilometres north of the city of Guiuan, USGS said.
The epicentre was around 600 kilometres east of the capital Manila, according to USGS.
Philippine seismologists measured the quake at a much-weaker 4.7-magnitude, said Alex Flores, duty officer at the operations centre of the government's National Disaster Risk Reduction and Management Council.
The council had not monitored any reports of casualties or damage, she added.
An aftershock measuring 5.4 in magnitude later struck around 66 miles north of Guiuan, the USGS recorded.
Officials at the state Philippine Institute of Volcanology and Seismology could not be reached for comment on Saturday night.
The Philippines sits on the Pacific "Ring of Fire" -- a belt around the Pacific Ocean where friction between shifting tectonic plates causes frequent earthquakes and volcanic activity.
A moderate 5.0-magnitude earthquake in November left at least 10 people injured when it hit a city in the southern Philippines.