Japan is one of the world’s most seismically active countries, sitting on top of four major tectonic plates along the western edge of the Pacific “Ring of Fire”.
The archipelago, home to around 125 million people, typically experiences hundreds of jolts every year and accounts for about 18 per cent of the world’s earthquakes.
The vast majority are mild, although the damage they cause varies according to their location and the depth below the Earth’s surface at which they strike.
It is haunted by the memory of a massive 9.0-magnitude undersea quake in 2011, which triggered a tsunami that killed or left missing around 18,500 people and wrecked the Fukushima nuclear plant.
On Apr 20 this year, a tremor measuring 7.7 hit the country’s north, injuring at least 10 people and shaking large buildings in Tokyo.
This prompted authorities to issue a special advisory warning of an increased risk of earthquakes of magnitude 8.0 or stronger.
The advisory was lifted after a week.
