Lesser-known Fault From Canada to California Capable of 9.0 Quake

Stretching from British Columbia to Northern California, the Cascadia Subduction Zone is the earthquake fault that gets all the attention in the Pacific Northwest, despite that — and partly because — it only moves every 300 to 500 years.

Quiet but gigantic in its potential to wreak havoc, this convergence of two tectonic plates is capable of producing a 9.0 earthquake, which would bring down buildings as far away as the Willamette Valley and send a roaring tsunami toward the Oregon Coast at jetliner speeds.

But other, lesser-known faults are in the same region, and scientists at Oregon State University now have a better understanding of one off of Oregon and more active than the San Andreas Fault in California — the epicenter of the 1989 Loma Prieta and the 1906 San Francisco earthquakes that killed thousands.

For the first time, scientists now know that the Blanco Transform Fault Zone, some 200 miles off the southern and central Oregon Coast, has produced 1,500 or more earthquakes of magnitude 4.0 or greater during the past four decades, along with thousands of smaller quakes. It has the potential to cause a magnitude 7.0 quake, which could trigger a much larger temblor from its neighbor, the Cascadia Subduction Zone.

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