How ‘megaquake’ advisory in Japan following earthquake could impact U.S. West Coast
BEND, Ore. (KTVZ) -- Japan’s government has issued a rare “megaquake advisory” after a 7.5 magnitude earthquake struck off the country’s northern coast on Tuesday, warning that a much larger offshore quake could generate a towering tsunami in the coming days.
Officials say a worst‑case “megaquake” in the Hokkaido–Sanriku region could produce waves approaching 100 feet in parts of Japan, cause nearly 200,000 deaths, and inflict massive damage on coastal communities.
Even though the chance of such a quake remains low, about 1%, the advisory is meant as a wake‑up call, rather than a precise prediction.
For Oregonians, the scenario has an eerie echo of March 2011, when a magnitude-9.0 earthquake off Japan unleashed a tsunami that crossed the Pacific and sent waves into harbors along the West Coast. That event damaged docks and boats and produced strong, unpredictable currents, despite the waves being far smaller here than in Japan.
KTVZ’s Seismic Shift series recently explored how a major Cascadia tsunami would send evacuees over the mountains to Central Oregon, straining housing and emergency services. A large Japan‑generated tsunami would not trigger the same mass displacement, but it would test coastal evacuation systems, communication with tourists, and the ability of ports to secure vessels and infrastructure ahead of time.
As Japan braces for the possibility of another powerful offshore quake, Oregon scientists and emergency managers are watching closely, preparing for a real‑time lesson in how tsunamis move across the Pacific.
KTVZ’s Claire Elmer spoke with postdoctoral scholar Erick Velasco, who studied tsunamis and earthquakes in Japan before his current research work at Oregon State University, about what Central Oregon needs to know about Japan’s advisory. Tune in for her report tonight on KTVZ News at 4:00 p.m. on FOX.
