Friday, February 13, 2015

When an earthquake occurs, is it possible to tell what the aftermath is going to be like?

There are earthquakes – and then there are their aftermaths. After my house stops shaking and I get up off the floor – assuming I still can – what else will happen?

Q: Hello! When an earthquake occurs, is it possible to tell what the aftermath is going to be like? If so, is there any way to prevent it?
- Tyler H

A: Urban engineers and earthquake specialists have intensively studied the consequences of earthquakes for at least a century and a half now. As a result, they have a pretty good understanding of what the consequences of a large earthquake will be like: how much damage will be caused by the initial event, and how much damage (and subsequent disruption) by aftershocks. Perhaps surprisingly, most of the truly catastrophic damage of the 1906 San Francisco earthquake came from the fires that raged for days following the initial massive shaking event. 

Engineers and urban planners have a good idea of where the water mains and power lines will be cut off, and where the economic corridors (food and fuel distribution via highways and railways, for instance) will be disrupted. With the advent of the internet and computer systems, warehousing of food in southern California has been consolidated in far fewer locations than during the 1960's. This means that a serious potential side effect of a large San Andreas earthquake will be... starvation. 

Earthquakes cannot yet be predicted, though that hope drives some of the most brilliant research minds I have personally ever met. Consequently, efforts have been under way for decades now, instead, on *mitigating* a large earthquake's effects. One aspect of this is "retro-fitting" older buildings to make them more earthquake resistant (not earthquake proof). Hand in hand with this are efforts to establish more stringent building codes - so newer buildings are already pretty earthquake resistant when they are first built. 

By hosting events like the Great Southern California Shakeout, the US Geological Survey, along with local and regional emergency personnel and individuals like you and I, all become more aware of what to expect from one of these terrible events. If we have an idea of what will happen, we can build realistic contingencies into our planning. As an individual or a family you can take part in this process by having a "72-hour kit" of food, water, and other necessities on hand in your own home. If your cultural or religious tradition encourages you to help others, you may also want to "amp up" your emergency supplies to 6 months or a year's worth in order to help your neighbors. 

We will never find enough money to make ALL buildings and ALL infrastructure 100% earthquake-proof. We CAN make buildings more earthquake RESISTANT, however. I bought a house in Washington State 12 years ago that met the more stringent modern building codes, so the insurance company gave me a 15% discount on my home owners insurance. But my house is only somewhat more resistant to earthquakes than one built in the 1950's - again, it's not earthquake-proof. I asked how much earthquake insurance might cost me to add to my home owners policy? I was told this would add 15% more onto my premium. 

I told my insurance agent to go ahead and add it on - it balances out in several senses of the word.

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