The lead author of a recent study about how major earthquakes in the Pacific Northwest have been historically linked to seismic events in California, specifically on the San Andreas Fault, says he sees some upside to the findings, at least for those of us in California.

Those among us who pay close attention to new earthquake science likely heard about the study that came out this fall that found evidence of the historical "partial synchronization" of the Cascadia subduction zone in the Pacific Northwest and the San Andreas Fault. The study's authors looked at the geological record of major seismic events on the Cascadia subduction zone and on the San Andreas, and found that major quakes on the northern San Andreas Fault were likely directly triggered by larger events in the Cascadia, occurring minutes, hours, or even days or months after.

Specifically, the 9.0+-magnitude event that occurred in the Pacific Northwest in the year 1700 — which was covered in a widely read 2015 New Yorker piece — triggered a similarly large quake on the northern San Andreas that occurred within 20 minutes to one year after the Cascadia event. Sedimentary evidence from beneath the sea floor confirms the two events were closely linked, the study says.

Now, the study's lead author, Bay Area native Chris Goldfinger, has sat down with the Chronicle to discuss his main takeaways from his years studying both fault zones. And he concludes that there is a silver lining in the findings, particularly for those living near the San Andreas Fault.

"If Cascadia went off, it would serve as a warning system to the Bay Area," Goldfinger tells the paper. He adds, "When you have one fault rupture, it transfers stress to nearby faults, in this case the northern part of the San Andreas fault. The issue is if there were a quake on the Cascadia, you wouldn’t know if San Andreas would go off in 10 minutes or 10 years — even as much as 50 years. But chances are it would be sooner than later."

Goldfinger notes that even a couple minutes warning would help save lives, with things like the BART system being able to keep trains out of tunnels, and bridges potentially able to be cleared of traffic.

He even suggests, and he doesn't seem to be joking, that if there were a major seismic disaster in the Cascadia subduction zone, it might be "a good time for a vacation in Tahoe." In other words: Head for the hills.

This early warning from a disastrous quake up north is cold comfort to residents of Seattle and Portland, but for those in Northern California, Goldfinger says, "I’m starting to see this as more of a positive than a problem."

Still, he says, such a double earthquake event would be devastating, both in terms of loss of life and economic impacts for the entire West Coast.

"Either one alone would be a national event, but my concern is the ability to respond to either event would be diminished because we would run out of resources," Goldfinger says, adding that airports and seaports would likely see major damage from Seattle potentially down to Los Angeles.

Now, we've been told for years that the next Big One in the Bay Area is more likely to occur on the Hayward Fault, because it is more "due" for a big event — the last big earthquake on that fault was in 1868, and such quakes appear to happen with about a 150-year frequency, you do the math. And a 2019 study suggested that a 7.0M quake on the Hayward Fault, centered under Oakland, would likely result in around 800 deaths and could leave around 52,000 homes on fire.

Meanwhile, the Cascadia zone, which is a convergent fault zone involving multiple tectonic plates sliding under the North American plate extending from Vancouver Island to Cape Mendocino, has a 37% chance of producing a 7.0M or greater quake in the next 50 years.

Also, the San Andreas Fault has a habit of producing "extra" events that aren't linked to the Cascadia fault at all. Goldfinger says that the catastrophic 1906 earthquake was just one of those.

Let this be yet another reminder to get your go-bags and household earthquake plans together!

Related: Hayward Fault Earthquake Scenario Imagines 52,000 Homes On Fire, 800 Deaths

Top image: Photo by ekrem osmanoglu