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  2 0 The cost of an earthquake retrofit for an average home is between $5000 and $15,000. Most homes in Seattle are valued between 350K and 900K. Does it make sense to spend $10,000 to secure an older home valued at $400,000? Of course, it all depends on whether there is likely to be an earthquake strong enough to cause the typical Seattle, wood-frame home to fail. We all remember the Nisqually earthquake of 2001. This type of quake occurs every 35 or so years. These earthquakes that fracture deep beneath the surface are destructive, but for most homeowners the damage is managable, even without retrofit. The two types of earthquakes which will do the most damage to our housing stock have not occurred in our lifetime. These we should be concerned about. The earthquake that hit Japan has us most nervous because of the similar subduction zone fault just off our coast. This is also the type of destructive quake to rock Chili last year. When the Cascadia fault moves there could be two to four minutes of Nisqually-type shaking in Seattle. Our housing stock was not built to take that kind of lateral movement for that long. Earthquake retrofit can strengthen a house to resist such shaking. There will always be damage to homes in a severe earthquake. The goal is to keep the house on the foundation and be able to clean up and go to bed in our own beds when it is over. Retrofit affords the best chance to stay in our homes after such an event. But will this subduction zone earthquake happen in our lifetimes? Perhaps. The fault moves every 300 to 500 years. We are in a window of risk since the fault last ruptured in January, 1700. For more details about the Cascadia earthquake go to: http://geology.about.com/od/quake_preparedness/a/aa_cascadiaEQ.htm Of greater concern is the Seattle fault which extends from the south end of Bainbridge Island across Puget Sound under the Seattle sports stadiums and follows I-5 to Issaquah. It is a shallow, strike fault that could produce a 7 to 7.5 magnitude earthquake. It would be hugely destructive to the city and its housing stock. The great Haiti quake in January, 2010 was similar to the Seattle Fault, as was the Christchurch, New Zealand earthquake which was so destructive last month. Read a detailed scenario for the Seattle fault at: http://www.eeri.org/site/projects/eq-scenarios/seattle-fault The last time the Seattle fault moved was 1100 years ago. The geology shows four large earthquakes on the fault in the past 3000 years. It is thought to produce a large earthquake every 700 to 1000 years. It is overdue! How do we compute this risk? It behooves us to be prepared. Retrofit the older home! Secure furniture! Collect disaster supplies! Anchor the water heater! Protect window glass! Install a gas shutoff valve! Create a disaster plan with your family! Prepare! Most homeowners have to pick and choose what projects they can do each year. If the roof is leaking, repair it. If the electrical wiring is dangerous take care of it. If the plumbing is leaking fix it. But do not add a new kitchen or bath to the old house until you have secured it with earthquake retrofit! A $40,000 kitchen remodel can be lost with the rest of the house in less than a minute of earthquake shaking. For those homeowners with more time than money, there is a do-it-yourself class in home earthquake retrofit offered every month through the Seattle Department of Emergency Management. http://www.seattle.gov/emergency/prepare/personal/home.htm. The Seattle Department of Planning also has good information at http://www.seattle.gov/dpd/Emergency/Earthquakes/Home_Retrofit_Program/DPDS_005871.asp. If you will allow a shameless plug, our website at www.EarthquakePrepared.com has a lot of good information about retrofit and earthquake preparation generally. For those still pondering the merits of earthquake retrofit I would offer the advice I give to clients. If you do not plan to be in your home for more than five years, retrofit will give you peace of mind, but you may not get your money back in resale. If that is a concern, speed up the process of selling and moving to a more secure place. Our home is usually our biggest asset. We do not want to lose it in a severe earthquake! Those planning to be in their home for more than five years should retrofit as soon as they can to protect their investment and their home! Bruce Schoonmaker answered in Earthquake! about 1 year ago | Report Comment on this answer Enter your comment or ask a new question New comments are not being accepted at this time.

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  2 1 The odds are 100% that once every 300 - 500 years we will get a quake that size. You 100 year chances are 30-20% any your average chances for any decade are 3-2%. However, it has been a very long time so each year that passes the odds go up. Basing your choice on the odds is fairly irresponsible, though. Granny Smith answered in Earthquake! about 1 year ago | Report Comment on this answer Enter your comment or ask a new question New comments are not being accepted at this time.

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