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The True Foundation of Seismic Safety

March 21, 1994

If we needed any further stimulus to prepare for more earthquakes it came Sunday afternoon with the 5.3 aftershock. We live in a shaky basin that sometimes seems almost unsuited for human habitation. It has become the urbanized home of 15 million people through human dominion over a beautiful though sometimes terrible natural environment. We learned what happens when our economic lifeblood, the freeways, are cut, and about the benefits of mass transit. And there are many still-unanswered questions about why certain buildings and roads collapsed and others did not.

But one lesson leaves no doubt: Thousands of people live in older homes that can and should be seismically strengthened. While its modern commercial architecture is often banal, Southern California is renowned for its graceful old wood-frame homes, many of them the Craftsman-style bungalows so common in Hollywood, Pasadena and the West Adams area. An earthquake can throw an entire frame off the foundation and turn a house into a heap of rubble.

The good news is that this is probably preventable. Last October one homeowner in Hollywood spent $3,400 to retrofit his house seismically, and he suffered no structural damage on Jan. 17. The cost is not trivial. But at less than 1% of the purchase price, he considered it good insurance and it paid off.

The procedure is not appropriate or necessary for all houses, certainly not for anything built since California building codes were upgraded in the 1960s. The work involves crawling under the house and performing two procedures on what is known as the cripple wall. This is a short wooden wall that extends up from the foundation and on which the frame rests. First the cripple wall is bolted to the concrete foundation. Then strong plywood is attached to hold the outer walls of the house to the cripple wall. The cost varies with the size of the house and accessibility to the foundation.

While nothing offers complete protection, James E. Russell, a civil engineer with the California Office of Emergency Services, says there is absolutely no question the work can save $40,000 to $80,000 in damage for the average house in a strong quake. A committee of the California Seismic Safety Commission is drawing up a standard retrofit code for localities.

But don't wait for that. Information is available at the 11 state quake service centers, or write the Assn. of Bay Area Governments, for "Strengthening Wood Frame Houses for Earthquake Safety" ($6, P.O. Box 2050, Oakland, Calif. 94604).

The handy can do the work themselves. But most people will want a licensed contractor with seismic experience and knowledge of local codes.

Do not let the healing forces of time dissuade you from getting this work done. It can make obtaining insurance easier and save your house and your life. The Northridge shaker demonstrated again that we live in quake country: Be prepared.

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