HONG KONG, July 13 (Xinhua) -- An earthquake measuring 6.1-magnitude jolted 169 km northwest of Naze, Japan, at 00:57:43 GMT on Saturday, the U.S. Geological Survey said.

The epicenter, with a depth of 242.18 km, was initially determined to be at 29.3349 degrees north latitude and 128.1371 degrees east longitude.