9.0 Quake in Pacific Northwest in 1700 Triggered Japan Tsunami, Scientists Say

A magnitude 9 earthquake struck the Pacific Northwest in January 1700, triggering a massive tsunami that flooded coastal Japan, researchers report today in the journal Nature. Japanese researchers reported last year that the tsunami hit Honshu Island on Jan. 27, 1700, and that it was probably triggered by a shift in the Cascadia subduction zone, a 600-mile fault stretching from British Columbia to Northern California.

Now, researchers from the University of Washington have provided local evidence of the quake. They studied six dead trees along a 60-mile section of the Washington coast and, by measuring tree rings, concluded that all died in the winter of 1699. Many researchers had not believed that a magnitude 9 temblor could occur on the Cascadia fault.