Sediment is blasted actively on the bottom of Biwako, the largest lake in Japan.
Mr. Kumagai ,the chairman of Lake Biwa environmental research institute talks, the environment of the late bottom is rapidly changing.
Since 2000, they have been investigating the bottom of the lake, 80~100 m deep by using submarine robot with video camera.
They have been checking the ground for longer than 10km from South to North.
In December of 2007,there were no sediment blasting observed but in December of 2009, they found 2 points every 1km. It increased to 9 points in December of 2010.
In January of 2012, it decreased to 7 points but the size of the blasting area increased from 1~2 m to 2~5 m.
Since 2008, the temperature of the water at 1.5m deep have became hotter than 1.0m. The bottom of the lake is heated.
Mr. Tsukuda Tameshige, the former assistant professor of Tokyo University earthquake research institute talks, the crustal change raised the pressure of underground, water underground or gas may be coming up from the cracks of the ground. The crust is highly distorted from Niigata to Kobe. Biwako is in the area.