The US Geological Survey said the temblor hit about 100 kilometres (62 miles) northeast of the main island in the early morning hours of Monday local time.
The Pacific Tsunami Warning Centre issued an alert saying hazardous waves could be possible cor coasts located within 300 kilometres (185 miles) of the epicentre. No reports of damage were immediately available.
Tonga is a country in Polynesia made up of 171 islands with a population of a little more than 100,000 people, most of whom live on the main island of Tongatapu.
It is more than 3,500 kilometres (2,000 miles) off of Australia’s east coast.
In the past 24 hours, there have been worldwide 1,770 quakes of magnitudes up to 7.0:
1 quake above magnitude 7
1 quake between magnitude 6 and 7
3 quakes between magnitude 5 and 6
51 quakes between magnitude 4 and 5
149 quakes between magnitude 3 and 4
366 quakes between magnitude 2 and 3
1,199 quakes below magnitude 2 that people normally don't feel.
Mag. 2.8 earthquake Japan: SE Off Miyagi Pref - 9 minutes ago
Latest felt Mag. 6.1 earthquake 82 km SE of Pangai - Tonga - 1 hour 42 minutes ago
Strongest today Mag. 7.0 73 km SE of Pangai - Tonga - 4 hours ago
