Japan's meteorological agency has lifted a tsunami advisory for Okinawa Prefecture in the country's southwest. However, officials are warning residents to stay alert as more tremors are possible.

Officials say a 30-centimeter tsunami was observed at Yonaguni Island at 9:18 a.m. and also at Miyako Island at 10:50 a.m. Japan time Wednesday. A 20-cm tsunami reached Ishigaki Island at 10:42 a.m.

The agency initially issued a tsunami warning after an earthquake hit off the coast of Taiwan just before 9 a.m., and later downgraded the warning to an advisory.

The meteorological agency says the focus of the magnitude-7.7 quake was 23 kilometers deep.

Japan's top government spokesperson says there are no reports of damage in the country so far. Chief Cabinet Secretary Hayashi Yoshimasa said, "We have established an emergency crisis headquarters. People's lives come first when taking necessary measures. We will continue to gather information on the latest situation."

This is the first time the meteorological agency has issued a tsunami warning for the coastal areas of Okinawa Prefecture since the 2011 Great East Japan Earthquake and Tsunami.