In this Reuters article the U.S. Geological Survey gives a 46% probability of a 7.5 or greater earthquake in the next 30 years in California with the most likely location being at the southern end of the San Andreas fault. With everybody’s mind on the recent disaster in Japan, they point out a few key differences between their scenario and the predicted “big one” here at home. Here are three key points to keep in mind:

1. Tsunamis in California are not likely. The fault off the coast of Japan is a “thrust” fault where the edges of two massive continental plates push against each other, creative subduction zones that displace large amounts of water. The fault in California is a “strike-slip” where the edges of the fault slide longitudinally against each other, displacing very little water.

2. California’s two nuclear power plants should not experience damage. That said, other lesser buildings will suffer from poor construction. Quoting the article, “Substandard construction poses a bigger problem in California . . . The Japanese have done a better job than we have done of retrofitting older buildings.” This was a surprise to me, however I am aware that there are still un- or marginally-reinforced masonry buildings here in California from the 60s and 70s that have yet to be upgraded. (Added 3/23/11: “Craig Comartin, a former president of the Earthquake Engineering Research Institute, said the state has 25,000 to 30,000 non-ductile concrete buildings.” http://goo.gl/JxwE3) It was these types of buildings, ubiquitous in Haiti, that caused so much devastation there. On the whole, California is much better prepared than it was when the 8.3 hit San Francisco in 1906. However, there are many more people who live here now.

3. Store water at home. It doesn’t take a big one to disrupt water distribution systems. The likelihood of a 6.7 or greater in the next 30 years, more akin to the Loma Prieta that we had back in 1989, is 99%. Having water storage is more important than food storage, and not that difficult to do. We have (20) 5-gallon Alhambra jugs of water in our garage. That’s not a lot of water, but if we had to ration that to one gallon per person per day, we would be taken care of for a few weeks.

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