The northern section last had a major rupture back in 1906. Back then, a far less populated San Francisco took the brunt of the tremors and 3,000 people died.
This means that estimating when the next major quake will occur, and precisely where it will take place on the fault network, is difficult to tell. The best estimates, as always in this case, come from the USGS – they claim that strain rates on the fault indicate that there’s a 99 percent chance a shallow 6.7M quake will emerge from San Andreas in the next 30 years.
Los Angeles has the most to worry about, as there is a 33 percent chance that it will experience a 7.5M event in the same time period. This would definitely qualify as the prophesied “big one”, enough to wipe off between 1-2 percent of US GDP in an instant and leave millions of people homeless.
The takeaway message from all this is that every day that passes without a major quake, the more likely it will be that the next event will be even more powerful and damaging. We know the big one’s coming, but it’s very difficult to pin down exactly when and scientists are doing their best to find out.
Part of the San Andreas Fault, as seen from above. Ikluft/Wikimedia Commons; CC BY 4.0
[H/T: LA Times]