According to the US Geological Survey, the quake was centred at 19.318°S 172.100°W, at a depth of 24.8km.
The quake struck at 11.48pm, Tongan Time.
A tsunami warning issued by the Tongan government has since been cancelled.
Reports that the quake had been upgraded to 7.9 have not been confirmed by the USGS.
Residents were advised to evacuate to higher ground as a precaution. Team members of the Tongan National Emergency Management Office (NEMO) were active throughout the night delivering water supplies to evacuees.
