By William S. Ginell
Adobe buildings—the vernacular earthen architecture of the Spanish colonial past in the Americas—are a vanishing feature of the western United States. In California, for example, fewer than 5 percent of the estimated 
By William S. Ginell
Adobe buildings—the vernacular earthen architecture of the Spanish colonial past in the Americas—are a vanishing feature of the western United States. In California, for example, fewer than 5 percent of the estimated 900 adobes originally constructed in the San Francisco Bay area still survive. Statewide, only about 350 historic adobes are left.
Many of the buildings now gone were destroyed by earthquakes, and those still standing remain highly vulnerable to future quakes. But because current methods of strengthening adobes are both invasive and expensive, most building owners have been reluctant to undertake retrofitting measures. Using materials such as steel and concrete, these methods often produce results that are too intrusive and are physically and aesthetically incompatible with adobe. In addition, they frequently involve architectural alterations inconsistent with preserving the historic fabric of the buildings, ignoring the fact that every part of an adobe—down to the individual, handmade bricks of dried mud—is an artifact whose modification or loss diminishes the historic record that the building represents.
In 1990 the Getty Conservation Institute initiated the Getty Seismic Adobe Project (GSAP) to investigate alternatives to existing methods of retrofitting. Six years later, after studying dozens of historic adobe buildings, analyzing recent earthquake d