Japan has issued its first-ever advisory on higher-than-usual risks of a megaquake after an earthquake of magnitude 7.1 jolted on Thursday at the edge of a tremulous seabed zone along the Pacific coast known as the Nankai Trough. A possible Nankai megaquake and tsunami disaster could kill hundreds of thousands of people and cause a trillion-dollar damage to Japan.
What is the risk of a megaquake?
Japan Meteorological Agency's Nankai Trough quake advisory panel said the chance of a bigger earthquake striking after a magnitude 7 tremor was once in a few hundred cases, relatively higher than regular times. Earthquakes with a magnitude larger than 8 are considered megaquakes.
Japan estimates the next Nankai Trough megaquake could be as powerful as magnitude 9.1.
University of Tokyo professor Naoshi Hirata, who chairs the panel, said in a press conference that residents in areas that would be hit by such a disaster should review evacuation procedures and stay vigilant for a week.
Japan is one of the world's most earthquake-prone nations sitting on the Pacific "Ring of Fire" arc of volcanoes and oceanic trenches. In 2011, more than 15,000 people were killed in a magnitude 9 quake in northeast Japan that triggered a tsunami and triple reactor meltdowns at a nuclear power plant.
How much damage can it do?
A megaquake could result in maximum measurable tremors to areas from central Shizuoka - about 150 km (93 miles) south of the capital, Tokyo - to southwestern Miyazaki. Tsunami waves of up to 30 metres (98 feet) may reach Japan's Pacific coasts within minutes after the quake, depending on the epicentre and tidal situation.
Coupled with landslides and fire, the disaster would be expected to claim the lives of as many as 323,000 people and destroy 2.38 million buildings, forcing nearly 10 million survivors to evacuate.
Economic damage could total up to 220 trillion yen ($1.50 trillion), or more than a third of Japan's annual gross domestic product, with long-lasting impacts on infrastructure and supply chains for coastal industrial powerhouses producing cars and other key Japanese products.
(With Reuters inputs)
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