Saturday, August 27, 2011

The Immense Cost of Japanese Dams and Dam-Related Landslides and Earthquake

The Immense Cost of Japanese Dams and Dam-Related Landslides and Earthquakes*

Masano Atsuko

Translated by Aaron Skabelund

It had been three months since the Iwate-Miyagi Nairiku Earthquake struck northern Honshu on 14 June 2008, triggering a huge landslide above Aratozawa Dam. The area hit by a landslide has been further carved by snow and rain, and trees and other vegetation are in disarray. The site looks like the day after a wretched barber had just given it a bad haircut. For the earth, this must be an embarrassing appearance.

According to the National Institute for Land and Infrastructure Management (Kokudou gijitsu sou-kenkyuusho; NILIM), the epicenter of the 7.2 magnitude quake was near Mt. Kurikoma on the border between three prefectures--Miyagi , Iwate, and Akita--and in the close vicinity of 15 dams (one which is still under construction) including Aratozawa to the southeast.

In this landscape carved by rivers, a landslide with an average depth of 55 meters, a width of 810 meters, and a length of 1400 meters slid as far as 140 meters off the side of the mastiff and into the back of the lake formed by the dam.

A few days after the earthquake, Tokyo University Professor Konagai Kazuo appeared on NHK television’s “Close-up Gendai” special, “The Mountain that Disappeared: The Iwate-Miyagi Nairiku Earthquake,” and explained that because ground water near the dam was high and because snowmelt had permeated the ground, the violent shaking of the earthquake had caused the massive landslide. Read More

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