May 6, 2011
Strengthening a residence through a home earthquake retrofit is as simple as ABC: anchor, brace and connect.
Most homes built in the past 30 years or so do not need a retrofit to hold steady in earthquakes, but older homes may need some foundation tune-ups. If the foundation is not secured to the rest of the structure, major damage can result from the ground shaking.
The earthquake in Japan — plus major temblors in New Zealand, Chile and Haiti in the past year — has renewed the focus on seismic safety at home.
“When the earth starts shaking sideways, the foundation moves with the earth,” Sound Seismic co-owner Leif Jackson said. “This big, massive object is not going to immediately move with the foundation. It’s going to kind of lag behind, and it’s going to lag behind when that foundation oscillates back in the opposite direction. So, the house and the foundation get out of synch, and it can get jolted off of the foundation.”
Though most homeowners can take some small steps to reduce earthquake risks, older homes make for the likeliest candidates for a seismic retrofit, due to the adoption of modern building codes from the mid-1970s onward.