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Is an Earthquake Proof House Possible?

Evidence from Actual Earthquakes 

Is an earthquake proof house possible? According to page 7 of this American Plywood Association report it is.  Bill Clinton surveying damage after the Northridge EarthquakeThe protection you will get from an effective seismic retrofit with enough foundation bolting, cripple wall bracing, and shear wall placement will provide as much earthquake proofing as you should ever need.    Some damage, such as cracks in the drywall or plaster will always occur, but we can still do our best to make sure a house is as earthquake proof as the house these engineers at Stanford University built.  Retrofitted houses will never be as earthquake resistant as these houses tested on a shake table. Retrofitted houses have however been tested in actual earthquakes, one in Los Angeles during the Northridge earthquake and one locally.  These earthquakes proved how close a retrofit can be to making a house earthquake proof.

An Earthquake Proof house Tested in a 1989 Loma Prieta Natural Laboratory

An experiment that proved seismic retrofits work was given to us by chance in the 1989 Loma Prieta earthquake.  An architect in Monterey County owned two turn-of-the-century houses that needed foundation bolts and cripple wall bracing.  These houses were identical in every way.    In 1988 he bolted one of them to the foundation, strengthened the cripple walls, and did a complete retrofit using the retrofit techniques  on this website.  The other house was not retrofitted.

Then the Loma Prieta earthquake occurred.   The un-retrofitted house slid off its foundation and sustained over two hundred thousand dollars of damage.  The other one, which had been bolted to the foundation and its cripple walls converted into shear walls, only had plaster cracks that were inexpensive to repair.  This house was fully habitable.  Even though it suffered minimal damage, for all intents and purposes, it was an earthquake-proof house.

Seismic Retrofitting is again Tested in the 1994 Northridge Earthquake

In another example in Los Angeles, Bill Clinton did a photo shoot in front of a retrofitted house which suffered minimal earthquake damage, next to a house that was severely damaged.  After this he funded FEMA to give hundreds of millions of dollars to retrofit homes in Los Angeles.

As said before, many people ask us if it is possible make an earthquake proof house.  We can only say Yes!   After the earthquake, while you are drinking a cup of coffee and watching the news, you will be glad you retrofitted your house and made it earthquake proof in a way only a seismic retrofit can.

The house below suffered minimal damage to the outside even though it fell off its foundation.  Inside it is a wreck, and all of it could have been avoided with a good residential seismic retrofit.

 

Old wood framed house fallen from foundation otherwise fully intact

 

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