A strong earthquake struck the South Pacific Island nation of Tonga on Monday, but there were no tsunami warnings or immediate reports of damage.

The quake had a preliminary magnitude of 6.6 when it hit at 9:47 a.m. local time, the U.S. Geological Survey said. Its epicenter was 198 kilometers (123 miles) north of the capital, Nuku’alofa, at a depth of 112 kilometers (70 miles).

The Hawaii-based Pacific Tsunami Warning Center said there was no risk of the quake causing a tsunami.

Tonga sits on the Pacific “Ring of Fire,” the arc of seismic faults around the Pacific Ocean where much of the world’s earthquake and volcanic activity occurs.