A magnitude 6.1 earthquake struck on Sunday centred 97km north-east of Ohonua, on the Pacific island of Tonga, the US Geological Survey reported.
The quake hit at 2156 GMT on Saturday with an epicentre depth of 10km, the US global quake monitor said.
The Pacific Tsunami Warning Centre issued no alerts, and there were no immediate reports of damage or casualties.
The reported epicentre lies within the so-called Pacific Ring of Fire, an area of regular seismic activity.
In February 2018, a 7.5 magnitude earthquake in Papua New Guinea killed 150 people and destroyed hundreds of buildings.