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Earthquake odds on the rise

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Chances of the big one striking somewhere in the Bay Area over the next 27 years rise to 72 percent, up from 63 just last year

Seven "significant fault zones" line the Bay Area. If you could predict which one is going to go off and when, you would be the greatest hero in the history of the state.

If, on the other hand, you can only project the likelihood of an earthquake over the course of the next few decades, you’re probably regarded as a gloomy reminder of a problem most people don’t much want to think about.

That’s unfair, but it’s the burden under which the Working Group On California Earthquake Probabilities operates as they labor on their terrifyingly titled but incredibly important Earthquake Rupture Forecasts, detailing the statistical probability of a major earthquake along certain fault lines in the next 30 years or so.

The odds are rising. That’s what they do naturally and inevitably as more years pass without a major event. The latest projections, released last week, bump us up to a 72 percent probability of the Big One (or multiple Big Ones) hitting somewhere in the San Andreas fault network by 2043.

This time last year it was only 63 percent, which was already too high for most people’s comfort. New data about new quakes (not including the 3.5 surprise that shook Oakland awake this week) gave the USGS-helmed group a much clearer picture of our seismic future, which is great news for science and terrible news for anyone with a healthy phobia of being crushed.

Of course, the odds of a quake hitting any particular section of a fault at a particularly strength are much lower; the chances of a 6.7 magnitude quake somewhere on our share of the San Andreas is only 22 percent. But that doesn’t diminish the greater net odds that it’s going to happen somewhere nearby sooner or later.

That a major earthquake is on the way is a constant given for the area, but not everyone treats it that way. Despite constant warning, a 2009 state of California study found that fewer than 40 percent of Northern Californians have a disaster plan.

While most people (86 percent) say they have food on hand to last three days, only 30 percent have sufficient water saved.

"It is worth noting that, for some of the earthquake preparedness and mitigation actions, a substantial number of respondents said they did not know whether they had done it or not," the report added.

So, if it’s been too long since your last unsubtle reminder to prepare, here’s one again. To prepare, we strongly encourage you to check out SF72.org.