Nearly 20 years ago, the San Francisco Bay Area was rocked by a 6.9 quake that killed 63 and injured nearly 4,000. Damage was estimated at more than $6 billion.
We did a test Thursday to find out if a house retro-fitted to withstand an earthquake could survive a 6.9 quake. We compared two walls that represent two common types of homes in Seattle. One was built to today's code or was retrofitted, while the other was built before 1985 before there were strict quake codes.
For the test, they used actual readings from the Loma Prieta quake 20 years ago.
In less than a second, in the unprotected house, the wooden beams in the basement cripple wall fail.
"The house would have actually fallen over about 3-feet off of its foundation, if this had been a real house," said Steven Pryor with Simpson Strong-Tie.
But the house that was retrofitted suffered no damage.
Peter Lynch wanted his old house upgraded.
"Peace of mind," Lynch said. "I just didn't want my house to fall down in the next earthquake."
Anchor bolts attached the sill plate to the foundation to keep the house from sliding side to side and slipping off the foundation. Other hardware makes the house stronger, and keeps the walls from lifting up.
The job cost about $10,000.
"There's still movement, so the thing is designed to have a little bit of motion, but it's going to make a big difference," said Tony Holder with Home Improvement Services.
It's estimated 200,000 homes in this area need an earthquake retrofit, and you can have an earthquake retrofit done even if you don't have a basement. They just go through the outside walls.
For some, this is a do-it-yourself project, but most people need a contractor. It's best to get one certified to do this work.
For more information:
Was your house built before 1980? You can get from home retrofit information from the city of Seattle. These two-hour classes are free. For more information, click here.
Seismic Retrofit Guide