The Japanese government has issued an urgent warning over the catastrophic damage which could be caused by an impending megaquake.
Experts now believe there is an 80 per cent chance of a magnitude nine tremor occurring in the Nankai Trough off Japan‘s Pacific coast within the next 30 years.
New government estimates show that this disaster would kill 300,000 in the worst-case scenario.
This includes 215,000 deaths caused by tsunami waves exceeding 30m (98ft) in some areas.
The Nankai Trough is a deep ocean trench formed by the boundary of two tectonic plates, which is hit by a megaquake once every 100 to 200 years.
In the deadliest scenario, the report predicts that 2.35million buildings would be destroyed by collapses, flooding and fires.
The destruction would cause damage worth £1.44trillion (214.2trillion yen) and create 12.3million evacuees.
That is the equivalent of displacing 10 per cent of the Japanese population within a week of the earthquake.
The Japanese government warns that a megaquake could kill 300,000 people. That is almost 20 times the deaths caused by the devastating Tohoku earthquake in 2011 (pictured)
According to a new analysis, an earthquake in the Nankai Trench off Japan’s Pacific coast would have devastating consequences. This map shows the intensity of tremors according to Japan’s seven-point scale
Japan sits directly on the Pacific Ring of Fire, a belt of intense seismic activity. One of the most dangerous regions is the 600-mile (900km) section known as the Nankai Trough which produces megaquakes once every 100 to 200 years
Japan is particularly exposed to deadly earthquakes because it sits on a vast belt of seismic activity known as the Pacific Ring of Fire.
This region is the source of about 81 per cent of the world’s large earthquakes due to the meeting of multiple tectonic plates.
One of the most dangerous regions is the Nankai Trench, where the Philippine Sea Plate is pushed beneath the Eurasian Plate.
This 600-mile (900km) trench has the potential to produce extremely large, and exceptionally deadly tremors known as megaquakes.
Last year, the Japanese government issued its first ever Nankai Trough megaquake advisory after a magnitude 7.1 earthquake hit southwestern Japan.
As the risk of a megaquake in the near future increases, the Japanese Cabinet Office has updated its impact estimates for the first time since 2013.
Experts calculated the seismic force of a magnitude nine earthquake in the trench and used this to calculate the flooding and tsunami risk for each part of the country.
This study revealed that stricter building requirements and flood defences have only slightly reduced the estimated deaths over the last decade.
If an earthquake occurred in the Nankai Trough the Japanese Government estimates the destruction would cause damage worth £1.44trillion (214.2trillion yen) and create 12.3million evacuees. Pictured: A road damaged by Japan’s 2024 Noto earthquake
In the deadliest scenario the report predicts that 2.35million buildings would be destroyed by collapses, flooding and fires. Pictured: A house destroyed by the 2024 Noto earthquake
If a megaquake occurs, 10 of the country’s 47 administrative prefectures will experience tremors with a rating of seven, the highest score on Japan’s earthquake severity scale.
An additional 24 prefectures will experience an earthquake rated at six on the severity scale.
While collapsing buildings will kill an estimated 73,000 people, the deadliest consequence will be the huge tsunami wave sweeping across the island.
When an earthquake occurs beneath the ocean floor, they push massive quantities of water into waves moving as fast as jet planes.
In 2011, a magnitude nine earthquake struck about 81 miles off the coast beneath the North Pacific.
The earthquake produced waves up to 40m (132ft) tall in some places and killed 15,500 people.
In addition, the flooding caused the meltdown of three nuclear reactors at the Fukushima power plant, releasing toxic waste into the environment and forcing thousands to flee their homes.
However, a megaquake in Nankai Trench could be even more devastating than the 2011 Tohoku Earthquake – the most powerful tremor in Japanese history.
The most dangerous aspect of the earthquake would be the tsunami wave that would hit Japan. This map shows the expected height of the tsunami wave with black regions showing waves above 20m and red showing waves from 10-20m in height
In 2011, a magnitude nine earthquake struck about 81 miles off the coast beneath the North Pacific. The earthquake produced waves up to 40m (132ft) tall in some places and killed 15,500 people. Pictured: Fishing boats washed up by the tsunami in Miyagi Prefecture
The government believes that an earthquake in the Nankai Trench would produce a tsunami more destructive than the 2011 Tohoku earthquake. Pictured: The city of Otsuchi after the 2011 earthquake
If a megaquake occurs in the Nankai Trough, the Japanese Government predicts that some regions will have as little as two minutes before the wave hits.
Waves up to 10m tall will hit Tokyo and 12 other prefectures along the southeast coast.
Meanwhile, the cities of Kuroshio and Tosashimizu in Kochi Prefecture will be engulfed by a wave 34m (112ft) tall.
As the waves break over the land, flooding of at least 30cm or deeper will cover roughly 444 square miles (1,151.5sq km)
In the worst-case scenario, the earthquake would occur during winter and at night when people are unprepared to evacuate.
In this situation, the number of deaths following the earthquake would also be extremely significant.
The report estimates the number of people who would die in the aftermath of the disaster.
This includes people who aren’t killed directly by the tremor or tsunami, but rather by factors like diseases or exposure to the elements.
After a Nankai Trench megaquake, waves up to 10m tall will hit Tokyo and 12 other prefectures along the southeast coast. Meanwhile, the cities of Kuroshio and Tosashimizu in Kochi Prefecture will be engulfed by a wave 34m (112ft) tall. Pictured: The first tsunami wave of the Tohoku earthquake washes over Kesennuma city
Extensive flooding from a tsunami creates ideal conditions for the spread of infectious diseases while the destruction of homes leaves millions vulnerable.
In cases such as last year’s Noto Peninsula Earthquake earthquakes, post-disaster causes have been even more deadly than the initial destruction.
The report estimates that disaster-related deaths following the initial destruction would range between 26,000 and 52,000 depending on the scenario.
That is 13 times higher than the number of people who died of post-disaster causes following the 2011 Tohoku earthquake.
The Earth is moving under our feet: Tectonic plates move through the mantle and produce Earthquakes as they scrape against each other
Tectonic plates are composed of Earth’s crust and the uppermost portion of the mantle.
Below is the asthenosphere: the warm, viscous conveyor belt of rock on which tectonic plates ride.
The Earth has fifteen tectonic plates (pictured) that together have moulded the shape of the landscape we see around us today
Earthquakes typically occur at the boundaries of tectonic plates, where one plate dips below another, thrusts another upward, or where plate edges scrape alongside each other.
Earthquakes rarely occur in the middle of plates, but they can happen when ancient faults or rifts far below the surface reactivate.
These areas are relatively weak compared to the surrounding plate, and can easily slip and cause an earthquake.
