Retrofits offer limited earthquake protection

Thomas Peele and Jessica Guynn of Contra Costa Times found that despite houses being retrofitted to keep them safe during an earthquake, less than a third of the houses inspected would survive a major earthquake. In an investigation of 35 retrofitted houses, the newspaper found that in 24 of the 35 homes , residents might have had a false sense of security about earthquake protection. "Scientists predict a magnitude 6.7 earthquake is likely to strike the Bay Area before 2032. Yet state and local building codes don't require specific standards for a safe voluntary seismic retrofit of a home." The investigation also found that in most cases, nails were either too small, which can leave connections weak, or too big, which can split critical wood blocks and that shear walls were made of misshapen pieces, or "quilt-works," of plywood rather than the full-size sheets needed to effectively transfer earthquake forces.