Your monthly reminder to finally pull that earthquake kit together has arrived. I believe it was just October when the last study came out informing us that there were four fault lines around the Bay that are "locked and loaded" and ready to blow at any point "in the next 30 years." Well, today we have another one. This study is looking at earthquake magnitude probability statewide over 30 years, and now puts the probability of an 8.0 or greater magnitude quake in California at 7 percent, up from 4.7 percent in 2008.
The new study from the US Geological Survey adds to previous studies by looking at the likelihood of multi-fault quakes, in which two or more adjacent faults rupture simultaneously which, ahem, happens to be the plot of new disaster flick San Andreas.
For the Bay Area, we can look forward to a 100 percent chance of a small quake (5.0) in the next few years, as this handy graphic from the Chronicle shows us. And there's now a 95 percent chance of something Loma Prieta-sized (6.9) hitting us, and a 76 percent chance that it will be 7.0 or greater.
The long overdue Hayward Fault has two spots of possible co-rupture with another fault, which would be the Rodgers Creek Fault in Napa to the north, and the Calavares Fault to the south.
Southern California has a 93 percent chance of seeing another quake the size of the '94 Northridge quake, at 6.7 magnitude. Also, the likelihood of a bigger quake in SoCal is slightly higher than in NorCal for the next 30-year period 36 percent of a 7.5 quake versus 28 percent up north, and 7 percent of 8.0 or greater, versus 5 percent up north.
In the good news column, there is no increased chance of earthquakes overall, compared to previous studies. As the Examiner points out, the expected frequency of major quakes (6.0 or greater) statewide has decreased from an average of one per 4.8 years to about one per 6.3 years.