Japan earthquake: Authorities issue MEGAQUAKE warning for the first time ever after tremors earlier in the same area 'one of the world's deadliest earthquakes' hit nearly 80 years ago<br />Tsunami waves have struck Japan's main southern island following powerful earthquakes off the coast early this morning.<br /><br />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. <br /><br />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. <br /><br />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.'<br /><br />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.'<br /><br />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. <br />
