magnitude of 6.1, struck between the islands of Okinawa in
southwest Japan and Taiwan, the U.S. Geological Survey said.
Japanese authorities lifted a tsunami alert issued earlier.
The strongest tremor struck at 10:46 a.m. Japan time and 9:46 a.m. Taiwan time at a depth of 10 kilometers (6 miles), 180 kilometers west of Naha in Okinawa and 360 kilometers east- northeast of Su-ao in Taiwan. The Japan Meteorological Agency said the magnitude was 6.7.
Japan's weather agency lifted its tsunami alert at 11:50 a.m., which warned that a 50 centimeter (20 inch) wave may strike the Miyako and Yaeyama island chains in southernmost Okinawa. No injuries or damage were reported, Kyodo News said.
A later tremor of 5.9 magnitude, initially measured at 6.3, struck in the vicinity at 11:23 a.m. Japan time. The first quake hit at 9:26 a.m. and had a magnitude of 6. That was followed by a 5.6 shock five minutes later. All quakes were revised from initial estimates that went as high as magnitude 6.4.
Three further tremors were recorded of 5.1 magnitude or higher by 2:23 p.m., the USGS said.