A strong earthquake with a preliminary magnitude of 6.7 has struck the Atlantic Ocean far south of Africa, centered near the Norwegian island of Bouvet, seismologists say. No tsunami alerts have been issued.

The earthquake, which struck at 6:43 p.m. local time (18:53 UTC) on Tuesday, was centered about 370 kilometers (230 miles) east of Bouvet Island, which is considered to be the most remote island in the world. It has no permanent population.

The U.S. Geological Survey (USGS) said Tuesday's earthquake had a preliminary magnitude of 6.7 and struck at a depth of 10 kilometers (6.2 miles), making it a shallow earthquake. The quake's epicenter is roughly halfway between South Africa and Antarctica.

Because of the magnitude and location, no tsunami watches or warnings were issued. "Based on earthquake information and historic tsunami records, the earthquake is not expected to generate a tsunami," the U.S. National Tsunami Warning Center said in a statement.

The Atlantic south of Africa is sometimes rattled by moderate earthquakes, but tremors exceeding magnitude 6 are rare. A moderate to strong earthquake struck near Bouvet Island in February 2006, causing the foundation of a scientific station there to weaken, which eventually led to its loss in a winter storm.