Bhubaneswar: After the devastating Myanmar earthquake that saw the human toll crossing the 2,700 mark, Japan, which has been rated among the world’s five largest seismic zones, government has on March 31 released the death and disaster projections from an expected Nankai Trough megaquake.
As per the Cabinet Note released and published in Japan’s well known daily The Asahi Shimbum, says that there is 80% chance of the mega earthquake hitting the country within 30 year period.
WHEN MEGA QUAKE MAY HIT JAPAN?
Though Earthquake prediction is hard to make, geologists predict the earthquake based on historical obesrvations. By that yardstick, it can be assumed when Japan may be getting jolted by another megaquake.
It needs mentioning here that the last mega earthquake (means magnitude of 8 and above) along the Nankai trough has taken place in the year 1946.
Then it was predicted that such mega quakes may hit along the Nankai trough in every 100-200 years.
Because, such a megaquake along the Nankai trough hit Japan in the year 1854.
By that yardstick, Japan may see a mega quake around the year 2038.
A latest study Japan Earthquake Research Committee has predicted the following.
According to the latest assessment in 2025, the probability of a magnitude 8 to 9 earthquake occurring along the Nankai Trough within the next 30 years has increased from around 74% - 81% in 2024 to 75% - 82% in 2025.
The JERC assessment , however, confirms that Japan may be recording a mega quake in the next 30 year period.
(see the image below)
(The red line and blue line respectively show the variation of probability based on the conservative model and the historical model.)
NANKAI TROUGH
According to the JERC, the Nankai Trough subduction zone is a typical subduction system characterized by subduction (plates going beneath the other) of multiple geological units of the Philippine Sea Plate (the Kyushu-Palau Ridge, the Shikoku Basin, the Kinan Seamount Chain, and the Izu-Bonin Arc) beneath the Eurasian Plate in the southwest of Japan.
The Nankai Trough runs from Shizouka Prefecture's Suruga Bay in the northeast to the Hyūganada Sea in the southwest, marking the line where the Philippine Sea Plate is subducted under the Eurasian Plate (see the image)
(Tectonic setting of the Nankai Trough megathrust. The grey area indicates the Philippine Sea Plate. The thick arrow indicates the plate convergence direction. The grey arrows indicate ground displacements. The light orange area corresponds to the maximum-possible fault area published by the Japanese Government.)
The JERC has already predicted that if a mega quake strikes along the Nankai trough, where the mega quake impact be felt in a big way. (see the image below)
WHAT MARCH 31 REPORT SAYS?
As per the cabinet note released, a mega quake would result in approximately 2,98,000 fatalities and 2.35 million buildings collapsing in a worst-case scenario.
However, the latest report on expected damage and death toll has decreased marginally compared to estimates from 10 years ago.
The previous estimates had indicated that the death toll would be 3,23,000 and the number of completely destroyed buildings would reach 2.386 million
(courtesy - The Asahi Shimbum)
Japan Earthquake Research Committee has predicted where the impact of mega quake will be felt most.
(courtesy: JERC)
THE FINER POINTS
- The expert panel assumed a magnitude-9 level earthquake originating in a sea area from Suruga Bay in Shizuoka Prefecture to the Hyuganada coast off Miyazaki Prefecture in the Kyushu region.
- The government had designated 707 cities, towns and villages in Tokyo and 28 prefectures across the nation, including inland areas, as areas that must take countermeasures against the megaquake in August last year.
- The March 31 report has designated 764 municipalities in Tokyo and 30 prefectures from Fukushima to Okinawa prefectures are said to be at risk of a seismic intensity of a lower 6 earthquake or stronger, or three-meter high or higher tsunami.
- A tsunami reaching a maximum 34 meters in height would engulf Kuroshio and Tosashimizu in Kochi Prefecture.
- Flooding of 30 centimeters or more will occur over a total area of approximately 1,151.5 square kilometers from Fukushima Prefecture to Okinawa Prefecture.
- The number of municipalities where a seismic intensity of 7 is expected to strike increased mainly in coastal areas from 143 to 149.
- The Japan government had set a goal of reducing deaths by 80 percent and completely destroyed buildings by 50 percent over 10 years
But the March 31 report shows the reduction is of only 20%
