The Goldfinger-led study took four years to complete and is based on 13 years of research. At 184 pages, it is the most comprehensive overview ever written of the Cascadia Subduction Zone....
a region off the Northwest coast where the Juan de Fuca tectonic plate is being subducted beneath the continent. Once thought to be a continuous fault line, Cascadia is now known to be at least partially segmented.
This segmentation is reflected in the region’s earthquake history, Goldfinger noted.
“Over the past 10,000 years, there have been 19 earthquakes that extended along most of the margin, stretching from southern Vancouver Island to the Oregon-California border,” Goldfinger noted. “These would typically be of a magnitude from about 8.7 to 9.2 – really huge earthquakes.
“We’ve also determined that there have been 22 additional earthquakes that involved just the southern end of the fault,” he added. “We are assuming that these are slightly smaller – more like 8.0 – but not necessarily. They were still very large earthquakes that if they happened today could have a devastating impact.”...
“By the year 2060, if we have not had an earthquake, we will have exceeded 85 percent of all the known intervals of earthquake recurrence in 10,000 years,” Patton said. “The interval between earthquakes ranges from a few decades to thousands of years. But we already have exceeded about three-fourths of them.”
Well the, that would point to being, on average, overdue.
Now I am going to be the devil’s advocate here: 13 “recent “ earthquakes is not significant over the life of the continent.
It is akin to predicting global temperatures using just the past 13 years.
If the study went back millions of years, there would be hundreds or thousands of observations.
I hope you understand my point. I am not trying to be obtuse.