Japan on megaquake alert

Japan remains on alert after the country issued its first advisory on higher-than-usual risks of a megaquake, which if it happened could cause trillions of dollars of damage to the economy.

The Japan Meteorological Agency (JMA) says the risk of a megaquake along its Pacific coast, known as the Nankai Trough, has increased after a magnitude 7.1 tremor hit the south-west island of Kyushu and triggered a tsunami warning on August 8.

Earthquakes greater than magnitude eight are considered megaquakes and Japan predicts the next one in Nankai Trough could be as powerful as magnitude 9.1, reports Reuters.

JMA’s quake advisory panel, pictured, explains the chance of a bigger earthquake striking after a magnitude seven tremor is currently one in a few hundred cases, relatively higher than regular times. 

Besides being widely felt across Japan, the panel notes a Nankai Trough megaquake could result in tsunami waves of up to 30 metres high hitting the country’s Pacific coasts within minutes.

The agency estimates the disaster, coupled with landslides and fire, could cause a maximum of 323,000 deaths and destroy 2.38 million buildings, reports Reuters.

Experts also predict the economic damage could reach up to ¥220 trillion (NZ$2.5tn), with significant impacts on infrastructure and supply chains for companies producing cars and other key Japanese products.

The last major quake in the Nankai Trough was a magnitude eight tremor and 6.9m tsunami waves in December 1946 that killed 1,330 people.