An earthquake with a preliminary magnitude of 7.1 struck Japan's southern Kumamoto prefecture on Tuesday, knocking out power to thousands of homes, stopping rail services and triggering warnings of tsunamis and aftershocks.
The Japanese government issued emergency earthquake warnings for Kumamoto, Nagasaki, Kagoshima, Fukuoka, Saga, Oita and Miyazaki prefectures, all on Japan's southern Kyushu island.
A tsunami warning for a wave measuring one metre (3.28 feet) was issued after the earthquake, the Japan Meteorological Agency said.
Kyushu Electric Power said about 40,000 homes had lost power as a result of the quake, while rail company JR Kyushu said it had suspended services, including its high-speed bullet trains.
There were no irregularities reported at nuclear power stations in the area, Japan's nuclear regulator said.
Companies including Sony and TSMC, the world's largest contract chipmaker, have plants in the quake area. A Sony spokesperson said the company was checking the situation. TSMC did not immediately respond to a request for comment.
A massive earthquake in Kumamoto 10 years ago killed 275 people and injured a further 2,739, according to an official count.
Japan is one of the world's most earthquake-prone countries, with a tremor occurring at least every five minutes. Located along the Ring of Fire of volcanoes and oceanic trenches partly encircling the Pacific Basin, the East Asian country accounts for about 20 per cent of the world's earthquakes with magnitudes of at least 6.0.
