The Japanese are afraid of the 'black tsunami' coming soon

A major earthquake may occur in the Nanhai trough basin, causing a black tsunami in Tosa Bay in Kochi Prefecture, which is likely to be higher than expected by the Japanese government.

The above information is based on a recent study by a group of scientists at Tohoku University, Kansai and other research institutes. The team presented findings at a meeting of the Japan Geological Science Union in Chiba on May 29.

During a major East Japan earthquake in 2011, it was said that a "black tsunami" flooded the bays and estuaries in Miyagi and Iwate prefectures, causing greater damage than a tsunami. often. Based on the findings related to the Nam Hai basin , its mind may be in the offshore areas from the Tokai region to the Kyushu region, it may be necessary to strengthen disaster response measures.

"Black tsunami" attacked Miyako, Iwate Prefecture in March 2011.(Photo: GOVERNMENT OF MIYAKO city).

"Black tsunami" will carry sediments accumulated in the seabed and other things, likely to occur in places such as harbors and estuaries, where sediment accumulation occurs. Such a tsunami will have more devastating power than tsunami is mainly sea water.

The researchers calculated the amount of sediment contained in the " black tsunami" based on the cases that occurred at Kesennuma Bay in Miyagi Prefecture. At that time, Miyagi was hit by a 10-meter tsunami attacking in a major East Japan earthquake in 2011.

After simulating how sediments move from Tosa Bay during the earthquake in the Nam Hai Basin, researchers found that sediment, up to 10m deep, will be swept up near the river mouth and into the coast. along with tsunami.

How to form black tsunami.(Photo: YOMIURI SHIMBUN).

The phenomenon of sediment suddenly being swept away from the ocean floor will make the area deeper, causing a large amount of seawater to pour in, thus causing tsunamis to follow sediments of a larger scale.

According to the team's simulation, tsunamis are expected to be about 13 meters high near the mouth of the Monobegawa River flowing through Nankoku and Konan in Kochi Prefecture - about 2 meters higher than the government expects. The tsunami will be about 12 meters high near the mouth of the Niodogawa River in Kochi City, which is 1m higher than the government's forecast.

It is feared that downtown Kochi may suffer more severe damage than expected by the government. Makoto Okamura, emeritus professor of earthquake geology at Kochi University, said: "Seabed sediments were discovered from earthquakes in the former Nam Hai basin. The impact of the black tsunami needs to be is considered".