A shallow 5.1-magnitude earthquake jolted waters off Taiwan and the southernmost tip of Japan on Tuesday, US geologists said, but there was no immediate tsunami warning.
The quake hit at a depth of just six kilometres (four miles) and its epicentre was 181 kilometres east of densely populated Taipei, or 112 kilometres off the Japanese island of Ishigaki, the US Geological Survey said.
There was no alert from the Hawaii-based Pacific Tsunami Warning Center.
Taiwan lies near the junction of two tectonic plates. A 7.6-magnitude quake killed around 2,400 people in September 1999.