A strong earthquake has hit off of the South Pacific nation of Vanuatu, but no tsunami warning was issued and there were no immediate reports of injuries or damage.

According to the U.S. Geological Survey, the quake struck Sunday 81 kilometers (50 miles) north of the town of Port Olry and 407 kilometers (253 miles) north of Vanuatu's capital, Port Vila. It had a depth of 35 kilometers (22 miles).

The Pacific Tsunami Warning Center did not issue any tsunami warnings.

Vanuatu sits on the Ring of Fire, the arc of seismic faults around the Pacific Ocean where earthquakes are common. The nation is also prone to volcanoes and cyclones, and has been ranked by the United Nations University as the world's most at-risk nation for natural disasters.