Japan has issued its first ever megaquake warning following tremors earlier today in the same area 'one of the world's deadliest earthquakes' hit almost 80 years ago. 

The 7.1 magnitude earthquake struck off the coast of Japan's southern island of Kyushu, close to the city of Nichinan, at 4.43pm local time. 

Japan's Meteorological Agency issued a tsunami warning following the powerful quake. They also took the unprecedented decision to issue a formal warning about a potential 'megaquake.'

The agency said that submarines in the Nankai Trough, where part of the Eurasian tectonic plate meets with the Philippine tectonic plate, found that the chances of a major earthquake in the region was 'relatively higher than usual for the next week.'

Earthquakes in the Nankai Trough typically occur every 100 to 150 years. The most recent quake to hit the area was 78 years ago in December 1946.