A strong earthquake registering 6.4 occurred off Japan's Izu Islands on Sunday morning, the U.S. Geological Survey said.
The tremor followed a stronger quake of 8.5 magnitude on Saturday which had an epicenter off the Ogasawara islands, south of Tokyo, which caused no serious damage. That quake was at a depth of 590 Km (370 miles).
The quake 398 Km (250 miles) south-east of the Izu Islands had a more shallow epicenter of 13.4 km (9.4 miles).