A tsunami warning for Tonga has been cancelled by the meteorological service.
Tonga's Metservice issued the warning just before 10am local time.
At 11am, it said based on tide gauge readings and advice from the Pacific Tsunami Warning Centre, the main threat had passed.
Small unusual waves, currents and abnormal tides may still affect some beaches and harbours for hours.
The US Geological Survey said the kingdom was shaken by a 6.6 quake, 70km northwest of Fangale'ounga.
The USGS said the quake was 112 kilometres deep.