Two strong earthquakes jolted the ocean floor off southern Japan on Monday, triggering tsunami warnings for a cluster of sub-tropical islands and shaking buildings in nearby Taiwan.
There were no immediate reports of casualties or damage.
A 6.7-magnitude quake struck in the morning southwest of Ishigaki-jima island in Japan's far southern Ryukyu Islands, followed by a 6.4-strength tremor in the evening, the US Geological Survey reported.
Japan's meteorological agency issued and lifted tsunami alerts both times for a group of islands in the East China Sea.
The quakes could be felt in Taipei but caused no damage.
The first quake struck at around (0536 IST) some 115 kilometers southwest of Ishigaki-jima, and the second at (1541 IST) 140 kilometres southwest of the island.
Both struck at a depth of about 10 kilometres, said Japan's meteorological agency, which measured the first quake at 6.8 and the second at 6.5.
Around 20 per cent of the world's most powerful earthquakes strike Japan, which is located at the intersection of several tectonic plates.
An earthquake of magnitude 6.4 hit off central Japan last Tuesday, killing one woman and injuring more than 120 people.
Taiwan is also quake-prone, located near the junction of two tectonic plates. A 7.6-magnitude quake killed around 2,400 people in 1999.