Items of Useless Information. No 8.

Lake Mead from space, November 1985. North is ...

Lake Mead from space Image via Wikipedia

Getting Water on Tap Causes Earthquakes.

Well not all earthquakes, and not simply by turning on a tap. Reservoirs trigger some earthquakes, and some large enough to be worrying. After a dam is built the water backing up behind the dam creating the reservoir has mass, this mass changes the distribution of pressure on the underlying bedrock. This change in pressure is considered to have been instrumental in triggering earthquakes near dams across the world, is suspected to be a contributing factor in many others and is feared at still others. In all at least 100 major Seismic events have been associated with the filling of reservoirs.

The first seismic event I am aware of being attributed to the change in weight distribution caused by a reservoir was a 5.6 quake which occurred in 1932 at Algeria’s Oued Fodda Dam. In 1967 in Koynanagar a magnitude 6.3 Earthquake occurred in Maharashtra, India with epicenter, fore and aftershocks all under or near the Koyna Dam reservoir, there were 180 deaths and 1,500 injuries, with the quake felt 230 km away in Bombay. On August 1, 1975, at Oroville, California, a magnitude 6.1 earthquake was attributed to seismic activity  resulting from the filling of a massive earth-fill dam.

The most serious case may be the 7.9-magnitude Sichuan earthquake in May 2008, which killed an estimated 80,000 people and has been linked to the construction of the Zipingpu Dam.

Other Dams causing concern include  the Kariba Dam on the Zambezi near the end of the Rift Valley, Since its construction and filling in the early 1960s, Kariba is believed to have caused numerous earthquakes. 20 of them magnitude 5 or larger.

The filling of the Katse Dam in Lesotho, and the Nurek Dam in Tajikistan have had earthquakes associated with them as did the filling of Lake Mead behind the Hoover Dam where more than a thousand tremors were recorded from 1935 onwards.

Very large dams can add an additional mass of upwards of 150 billion metric tons, to the landscape, so it is hardly surprising that they change the shape of the land underneath them. It is generally argued that problems occur when dams exceed heights of 80 meters.

Worryingly the greatest magnitude quakes seem to be associated with the largest Dams and associated Resovoirs.

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About Transremaxculver

An entirely fictitious username I created for posting on 'alt.religion.scientology', Scientology is something of which I am highly critical. For those of you who don't know, the Church of Scientology have a habit of making life very uncomfortable for even the most legitimate of critics, which is why this username is completely anonymous. Anyway I have become quite fond of this username, and although it has to some extent outgrown it's original purpose, I think a blog is perhaps the right place for me/it to continue to grow and develop.
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