Newly refined fault forecasts for California

Those of us in California will take special interest in the recently revised earthquake forecast model by the U.S. Geological Survey. Depending on where in the state you live, there’s probably some good news and bad news. And then there’s the news concerning how the model itself was revised.

The old forecast model apparently looked at faults in isolation. But the real world if obviously messier than that, and faults, such as the Hayward and Calaveras that run through Oakland and Fremont, run into each other. So when one fault shifts, some of that energy gets shared with its neighbors, changing the pressure that they’re under at that moment.

So with this more sophisticated model, the major shifts in the forecast are that moderate earthquakes are actually less likely, but large earthquakes, magnitude 8 or higher, are actually slightly more likely than previously estimated. Now since “more” or “less likely” isn’t a lot to work with, the percent chances these events are around 5.7% of a 7.5 quake and a meager 2.1% of an 8.0 quake… over the next 30 years. And the odds are powerful, multifault, Michael Bay-grade quakes over magnitude 8? We don’t even get numbers for that— only that they’re “exceedingly rare.”

Time to panic? No, but probably a good reminder to set up an emergency plan.

Source: New Earthquake Forecast: Less Frequent ‘Moderate’ Quakes by Dan Brekke, The California Report