India, July 28 -- A powerful earthquake with a preliminary magnitude of 7.1 struck off the coast of Kumamoto on Japan's southern main island of Kyushu on Tuesday afternoon, prompting the Japan Meteorological Agency (JMA) to issue a tsunami advisory.

The quake struck at 4:27 pm local time (0727 GMT) at a depth of 10 kilometres (6 miles) beneath the seabed, according to the JMA. The agency said the shaking reached the maximum intensity of 7 on Japan's Shindo seismic scale, which measures the strength of ground shaking.

Authorities warned that tsunami waves of up to one metre (three feet) could reach parts of the coast at around 5:00 pm local time. Public broadcaster NHK reported that waves of up to that height may already have been record...