San Diego tends to take comfort in its distance from the notorious San Andreas Fault--perhaps even now, when the effects of a major earthquake are so vividly present in the San Francisco Bay Area. Earthquakes of any consequence are rare here--a 5.3 quake in 1986 was the largest in recent history.
But that sense of immunity rests on a shaky foundation, because so little is known about the Rose Canyon Fault line, which runs under heavily populated coastal communities. Officially, Rose Canyon is designated a "potentially active" fault. Geologists and seismologists, however, increasingly believe that Rose Canyon is active. Additional evidence was found just a few months ago by seismologists working at a San Diego Gas & Electric site.
San Diego's disaster plans and building code restrictions, however, are based on incomplete information and assumptions.
Now is the time to start correcting that with research.
Such research will be difficult and expensive, requiring state and federal help, because so much of the land above the fault is heavily developed. For the same reason, if geologists discover that the dangers are greater than expected, the remedies could also be costly.
But the price of ignorance could prove more costly and mean greater loss of life.
Another particular vulnerability for San Diego County, in the event of a major Southern California earthquake, is water supply. If the major distribution lines, which bring in 90% of the county's water, were ruptured, large parts of North County could be reduced to just survival amounts of water, officials say. Because it is at the end of the water delivery line, San Diego County has access to fewer backup supplies than most of the Los Angeles Basin. Water for business and agriculture would be sharply curtailed or eliminated, with devastating economic consequences.
Finding new ways to store water will not be easy, as the County Water Authority found when it tried unsuccessfully for years to get permission to build Pamo Dam. The CWA wisely backed off from that proposal and is now studying a wider range of alternatives.
But, when that study is completed, it will be time to make some decisions and act upon them. San Diego does have some justifiable reasons for solace. Most of our buildings are relatively new, so they are more likely to withstand a major earthquake. And the county is one of only three in the state with a disaster plan that includes a joint powers agreement among all local governments to assure regional coordination of services.
But, while the lessons of San Francisco are still fresh, San Diego needs to fill the gaps in its plans, learning more about Rose Canyon and taking steps to increase our water reserves.