A pair of strong earthquakes has struck off the South Pacific nation of Tonga, but there were no immediate reports of injuries or damage and no tsunami warning was issued.

The U.S. Geological Survey says the first quake had a magnitude of 6.4 and a depth of 11.5 kilometers (7 miles), striking 109 kilometers (68 miles) northeast of Tonga's Hihifo district Monday evening. The second had a magnitude of 6.8 and a depth of 10 kilometers (6 miles) and struck 99 kilometers (62 miles) northeast of Hihifo.

Earlier Monday, a powerful quake rattled Papua New Guinea, generating a small tsunami but prompting no reports of injuries.

Earthquakes are common in the region, which lies on the "Ring of Fire" — an arc of earthquake and volcanic activity.