A strong earthquake has struck off an island chain south of Tokyo, but officials say there is no danger of a tsunami.

Japan's Meteorological Agency said the earthquake hit Tuesday evening and measured a preliminary magnitude of 6.9. It said it was located very deep, about 480 kilometers (300 miles) below the ocean's surface. Deep earthquakes generally cause less damage.

The agency said it was centered west of the Ogasawara island chain in the Pacific Ocean about 1,000 kilometers (600 miles) south of Tokyo.

Some islands in the chain were shaken strongly by the quake, but it was hardly felt in Tokyo.

Japan sits along the Pacific "Ring of Fire," the arc of seismic faults around the Pacific Ocean where earthquakes and volcanoes are common.