A strong 6.4-magnitude earthquake was detected at sea in the southern Philippines on Monday, the US Geological Survey said, but there were no reports of damage and no tsunami warning issued.
The Philippine Institute of Volcanology and Seismology measured the quake at 6.1 magnitude.
The quake was detected 88 kilometres (55 miles) southeast from the coastal town of Don Marcelino but was barely noticed by residents, said the chief government seismologist Renato Solidum.
"It is not alarming," he told AFP.
The quake was tectonic in origin and had a depth of about 10 kilometres, he added.