The quake struck 183 miles (294 kilometers) northwest of the Vanuatu island of Santo, and 354 miles (596 kilometers) northwest of the capital of Port Vila, at a depth of 21 miles (35 kilometers).
The Pacific Tsunami Warning Center immediately issued a regional tsunami warning for 11 nations and territories, including Vanuatu, the Solomon Islands, Papua New Guinea, Nauru, Fiji and Kiribati. A tsunami watch, a lower level of alert, was in effect as far away as Australia and New Zealand.
There were no immediate reports of injury or damage from officials in Vanuatu, a chain of 83 islands. It lies just over 1,400 miles (2,200 kilometers) northeast of Sydney, Australia.
The latest warning comes just two weeks after a quake of magnitude 8.3 rocked the South Pacific near Samoa, sparking tsunami waves that killed at least 178 people and devastated coastal villages in Samoa, American Samoa and in northern Tonga.
Meanwhile, the U.S. Geological Survey reported a strong earthquake struck south of the Philippines on Thursday morning local time.
The quake had a preliminary magnitude of 6.7 and was located in the Celebes Sea, 175 miles (282 kilometers) southeast of Jolo, Sulu Archipelago, and 730 miles (1,175 kilometers) south of Manila. The quake hit at 5:41 a.m. Thursday local time.
USGS did not report any damages or injuries.
(This version CORRECTS ADDS additional detail on areas of alert; corrects to 83 islands in Vanuatu. For global distribution.)