Japan ‘megaquake’ warning highlights Cascadia concerns on West Coast
(Update: adding video, interview with researcher)
BEND, Ore. (KTVZ) -- A new “megaquake advisory” in Japan is raising questions about what it could mean for Pacific coastal communities — including here in Oregon.
The advisory was issued after a magnitude 7.5 earthquake struck Japan just days ago on December 8th. 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 scientists estimate the chances of such an event are only about 1%, Japan’s new advisory system is meant as a wake‑up call — not a precise prediction. It was created after the devastating 2011 earthquake and tsunami that killed more than 18,000 people. Under the system, when a quake stronger than magnitude 7.0 hits certain areas, authorities issue an alert that a much larger quake could follow in the coming days.
“This is not a prediction. This is a probabilistic warning,” Erick Velasco, a seismic expert and postdoctoral researcher with Oregon State University, told KTVZ News on Wednesday. “This is to practice our confidence on how to respond to an earthquake. And that’s also happening in Japan. This is not to scare people — this is rather to be prepared.”
For many Oregonians, the warning carries an eerie echo from the past. In March 2011, a magnitude‑9.0 earthquake off Japan unleashed a tsunami that crossed the Pacific, sending waves into harbors along the West Coast. While the waves were far smaller here than in Japan, they still damaged docks and boats and generated hazardous currents that caught some mariners off guard.
KTVZ’s Seismic Shift series recently explored how a major Cascadia Subduction Zone quake could similarly send evacuees pouring over the mountains into Central Oregon, straining housing and emergency services. A large Japan‑generated tsunami wouldn’t trigger the same mass displacement, but it would still test coastal evacuation systems, communication with tourists, and the ability of ports to secure vessels and infrastructure ahead of time.
If a tsunami were generated by Japan’s latest quake, Jonathan Allan with the Oregon Department of Geology and Minerals told KTVZ in an email it would take roughly nine to 10 hours to reach Oregon’s coast — time that could mean the difference between safety and disaster.
Velasco, who studied for his doctorate in Japan, reiterated, “If this kind of earthquake and tsunami happens in Japan, we will have some hours to respond in the U.S. So we have to be ready, and we need to be prepared. That’s the invitation here.”
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.
Velasco added that Japan’s experience shows the power of public education and collective action. During the 2011 disaster, more than a million people safely evacuated — a success he credits to consistent drills and community-wide awareness.
“If we work as a community and collaborate with each other,” he said, “we will be able to prepare for these types of events.”
The key message, experts stress, isn’t fear — it’s readiness.
