National broadcaster NHK said waves were possible on several islands in the southern Okinawa chain after a very shallow quake centred on Yonaguni in the southwest, near Taiwan. Taiwan's Central News Agency reported that the tremors were felt across the island, including in the capital, Taipei.
Witnesses said buildings swayed in Taipei but there was no visible damage in the Taiwan capital.
"We are issuing warnings via the radio," Satoshi Shimoji of the Miyako City government told NHK. "We want residents to get as far as possible from the sea," he said.
The quake had a reported depth of 18 miles (28.9 kilometers). Initially, the USGS had estimated the depth at 0.6 miles (1 kilometre).
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