A strong earthquake struck off the Pacific island nation of Tonga on early Friday afternoon, seismologists said, but there were no immediate reports of damage or casualties.

The 6.4-magnitude earthquake at 12.07 p.m. local time (2300 GMT Thursday) was centered about 50 kilometers (31 miles) northeast of Niuafo'ou, a volcanic rim island with a population of around 600 people. It struck about 9.8 kilometers (6.1 miles) deep, making it a shallow earthquake, according to the United States Geological Survey (USGS).
There were no immediate reports of damage or casualties, but the USGS estimated that people on Niuafo'ou may have felt moderate shaking which could potentially result in light damage. Some 55,000 people on islands farther away may have felt light shaking.
As earthquakes below magnitude 7 do usually not generate tsunamis, no tsunami warning was issued by the Pacific Tsunami Warning Center.
Tonga is on the so-called 'Pacific Ring of Fire', an arc of fault lines circling the Pacific Basin that is prone to frequent and large earthquakes. Volcanic eruptions also occur frequently in the region, which is one of the most geologically active parts in the world.
Tonga, with a population of around 104,000 people, is made up of 169 islands sprinkled over the Pacific Ocean about one-third of the way from New Zealand to Hawaii. Only thirty-nine of the islands are inhabited.
On September 29, 2009, an 8.1-magnitude earthquake struck 185 kilometers (115 miles) east-northeast of Hihifo on Tonga, unleashing giant tsunamis that killed nearly 200 people and injured hundreds more on Tonga, American Samoa, Samoa, and other nearby islands.