Monday, September 29, 2014

EARTHQUAKES AND WATER

Everybody is afraid of earthquakes. Well, almost everybody. Structural engineers thrive after an earthquake hits. They pray to God for an earthquake every evening before going to bed. Business is booming, good times are back.

Jokes aside, why are people afraid of earthquakes? Of course, nobody wants to die or get seriously injured in an earthquake, or get their building damaged. But the truth is that with our ever improving building codes and hopefully mandatory upgrades of existing non-conforming or unsafe buildings, the chances of dying and building collapses are dwindling. There is another danger though. One not too many people think of in a major earthquake. What would Southern California do without water for 6 to 12 months? Let me explain.

Most of our water (80%) comes from outside Los Angeles. All that important water has to cross the San Andreas Fault line to get to us. As I mentioned in one of my previous newsletters, a major earthquake along the San Andreas will move the earth’s crust 10-30 feet on one side in respect to the other. The city of Los Angeles aqueduct crosses the San Andreas in a wooden tunnel about 9 feet diameter built in 1908. That is a lot of water. It won't exist afterwards. If all the water connections to Los Angeles are cut off, the estimated time to repair them is about 12 to 18 months. Eighteen months with only 20% of our water? That's a crisis of biblical proportions. We are already having water problems just because of not enough snow has fallen in our mountains, contributing to the current three years of very severe drought in California. People and businesses will leave; our economy will be in shambles. Haven't I scared you yet? Listen to this. Most big earthquakes break gas lines, too, although there is lots of improvement lately with earthquake proofed gas line connections. Broken gas lines create fires. About 95% of our buildings are built from wood, Type-V construction. Can you imagine a city wide fire with limited or no water for firefighters to fight?

The only way our economy can function after a big San Andreas earthquake is to completely reengineer all those fault crossings so they can't break. There are types of pipe that won't break in earthquakes. Japan and New Zealand -- both countries with lots of earthquakes -- are way ahead of us mandating earthquake resistant piping. The city of San Francisco has a backup system of cisterns buried under the city, completely separate from the drinking water system that they built after the devastating 1906 earthquake. As you know that devastating earthquake caused a limited amount of damage, but the subsequent fire destroyed almost the entire city. The city of Los Angeles has a similar backup system --the San Fernando Valley aquifer. We just have to clean it up but it will cost a lot of money. Conclusions? We've got this fault-crossing problem and we have to spend lots of money and resources to figure out what to do to avoid a major economic disaster by fixing our water supply system.

Source: http://www.laaqueduct100.com/


Interesting isn't it? What are your thoughts? I'd love to hear it thru our Erdelyi blog.