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Geologic Column
California Wines: Well-Shaken and Stirred
Susan Hough

When wine country is also earthquake country, wineries take their lumps along with everyone and everything else. The 1980 Livermore earthquake caused huge stainless-steel wine vats to buckle; the recent 2003 San Simeon earthquake toppled wine barrels and caused other non-structural damage at wineries in the Paso Robles area.

Virtually any site, and therefore any winery, in California is at risk of earthquake damage. While earthquakes pose higher risks to some parts of the state than others, they are possible just about everywhere. Moreover, a structure can sustain damage from a larger earthquake, even if it strikes some distance away. For example, when the San Andreas Fault south of Parkfield ruptures again, as it last did in 1857, wineries in the Paso Robles area could find themselves well-shaken once again (a good thing for martinis perhaps, but a very bad thing for wines).

Some wineries in California have, most unfortuitously, been built immediately atop major faults. The former Gallegos winery was built directly atop the creeping Hayward Fault in the city of Hayward, but the 1906 earthquake destroyed the structure even before creep had a chance to tear it apart. A surviving fragment of the foundation wall does continue to shift and rotate as the fault continues to creep — giving the site a low-tech creep-meter to go with the high-tech instrument more recently installed.

A more famous (in earth science circles, anyway) example is the former Almaden-Cienega winery, which sits squarely astride the creeping San Andreas Fault in a bucolic valley a few miles south of the town of Hollister. The fault crosses and splits a concrete culvert to the immediate south of the winery building. Photographs of this culvert have appeared in numerous generations of geology and seismology books, many of which have continued to use the name Almaden-Cienega years after the winery was sold in 1988 and began operation as the DeRose winery. (An amusing exercise is to do a Web search for both names: The former yields geology/hazard sites, while the latter yields wine sites.)

But I digress. At the DeRose winery site, the fault bisects not only the culvert but also the main winery building itself, posing a substantial ongoing engineering challenge, as half of the structure shifts steadily away from the other half. The solution has been to build new supports under parts of the building that are shifting away from their original structural supports. At least so far, the winery is still standing and very much in operation.

Despite these examples, however, California's wineries have not suffered disproportionately in California's earthquakes; in fact, they represent a microcosm of the state as a whole — a state where virtually every structure is at risk from earthquakes, and where some older structures were built directly on top of active, even creeping, faults. The Alquist-Priolo Act, which defines a no-build zone of 50 feet around the surface trace of active faults, is only a few decades old and does not cover structures that predate the act. (Thus, the DeRose winery is exempt from the law.)

Perhaps in some respects, California's wineries represent not only a microcosm but also a metaphor for Californians' uneasy coexistence with the powerful natural forces that continue to shape the landscape. Although the San Simeon earthquake did cause two fatalities and some serious structural damage to unreinforced older masonry, nonstructural damage was the norm among a population of structures, wineries included, that have mostly been built to very strict building codes over the years.

But perhaps the most apt metaphor can be found if we return to the DeRose winery — a structure that, like the rest of the state, has made its stand smack in the middle of earthquake country. It seems so wildly improbable, if not wildly insane, to put down roots in a place where the terra firma is not always firm. And that California is earthquake country has never been the slightest surprise: When Gaspar de Portola led the very first European expedition into the state in 1769, he and his men were rocked by a series of earthquakes in present-day Santa Ana, south of Los Angeles. Other early explorers heard tales of earlier earthquakes from California's native people.

A person would have to be crazy to live in a place like this, and yet about 30 million people have chosen to make the state our home. It might be great grist for jokes, but it starts to defy sensibility to imagine that 30 million people are simply nuts. And the plucky DeRose winery suggests an alternate possibility — that the very forces creating California's natural hazards also create a landscape that is, at least while it is holding still, eminently agreeable … to grapes and humans alike. California wines might be well-shaken and stirred once in a while, but they also rank among the best in the world.

Hough is a mostly sane transplant to California, where she is a seismologist at the U.S. Geological Survey in Pasadena. She is also author of Finding Fault in California: An Earthquake Tourist's Guide and is a Geotimes corresponding editor.

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