According to the Japan Meteorological Agency (JMA), a magnitude 5.6 offshore quake jolted Miyazaki and neighboring prefectures at 7:43 a.m. local time (2243 GMT Thursday).

The quake was centered in the Hyuga-nada Sea, which is part of the Pacific Ocean that lies off the eastern shore of Kyushu Island, to the south-west of the island of Honshu, off the south coast of Japan.

The JMA said the quake struck registered 3 on Japan's seismic scale which peaks at 7 in Miyazaki and Kagoshima prefectures.

At 0848 hrs local time (2348 GMT Thursday), a more powerful earthquake with a preliminary magnitude of 6.3 struck the same area, registering lower 5 on Japan's seismic scale in Miyazaki Prefecture, the agency said.

The second temblor to strike the region registered 4 on Japan's seismic scale in Kumamoto, Oita and Kagoshima prefectures, the JMA said, and 3 in other surrounding regions.

A magnitude 4.9 quake, thereafter, struck the same point at 9:07 a.m. local time (0007 GMT Friday), the agency said, with the temblor registering 3 on Japan's seismic scale in Miyazaki.

The JMA said that no tsunami warnings or advisories are in effect as a result of the triple quakes, and there have been no immediate reports of injuries as a result of the temblors.

Nuclear power stations in the region have not reported any abnormalities, according to Japan's nuclear watchdog.

Local media reported, however, the quakes may delay flights at Miyazaki, Kumamoto, Kagoshima airports.