Great Washington ShakeOut: Coastal tsunami risks

We are 30 minutes away from the Great Washington Shakeout, the largest earthquake drill in the U.S. That's coming up today at 10.15 a.m. And people are going to practice earthquake safety drills at work, school, and home. Much of our beloved western Washington lies on the Pacific Coast. And below the beautiful water that surrounds us is a fault line that has the potential to trigger a catastrophic tsunami. This morning we're talking about all things emergency preparedness as we learn more about the Great Shakeout. And this morning, we're joined by University of Washington Senior Research Scientist, Dr. Yong Wei, to talk more about the potential big one. And it's more than just a jolt on land. Good morning, Dr. Wei. Thanks for joining us. Good morning. So what exactly is the Cascadia Subduction Zone for folks that don't really know much about that? Well, Cascadia Subduction Zone is a big earthquake fault running from Canada to North California. So a Cascadia Subduction Zone earthquake can initially trigger up to like six, seven feet of coastal subsidence. And the waves can quickly arrive at the coastline within 15 to 30 minutes. So the low-lying coastal communities are most vulnerable with maximum tsunami height reaching up to 50 feet or more along parts of the open coast. It's hard to picture what a tsunami can do, but we saw that in Japan with the devastating tsunamis that hit that country when they had their massive earthquake. What do you expect to happen if we do get a tsunami that large to our coastline? So usually during a local earthquake like what we have here, Seattle Fault, which is running just like beneath us, stretching across Puget Sound, downtown Seattle, and also Lake Washington. Once it's triggered, and then we can expect localized hazards, including strong earthquake shaking and southern coastal uplift and subsidence, and also locally generated tsunamis running up to like 16 feet that can affect a densely populated urban area within just a few minutes. Okay. And what about out along the coastline? So what would you expect out there in areas like, let's say, ocean shores and spots along the coast that, you know, there's still a lot of people that visit those communities, especially in the summertime? Yeah, so in the video you can see that, you know, a Cascadia Subduction earthquake can potentially generate tsunamis up to 50 feet around those areas. So that's where the vertical evacuation structures come in. Okay, yeah. So those vertical evacuation structures, I did a story on this a couple of years ago. Those are built, those are made so that people can get up high really quick, right? Currently, we only have two completed ones out on the Washington coastline. There's a third one being made that was approved out in the Westport area. That's being built. That's expected to open next summer, late next summer. So I've heard we need up to 50 to 80 of these. Do you have any idea what the holdup is on getting these things built? Those things are really important, actually, because the tsunami waves can hit the coastline within 15-20 minutes so they need a quick and rapidly accessible safe havens for local communities so you mentioned about the two and a half structures and they provide really accessible evacuation routes for local communities And those are reinforced concrete and the steel towers can provide a, you know, really strong protection for local people to evacuate. I know that this is tough because those structures can cost millions of dollars and some of these local small communities can't afford that. So they're relying on federal money to get those things built. So, yeah, anyway, that is something we'll certainly be following, but it's about getting the higher ground out there on the coast, right? That's what you want to do right away. Yes, exactly. Yes. And yeah, as you said, Washington State does need dozens of those vertical evacuation structures to fully address the coastal evacuation gaps. So also tsunami waves, they are not a single wave, they are a train of waves. So they can continue to impact the coastline for hours or even days. So people should stay away from the waterfront until an official evacuation is issued. Really interesting stuff, very important stuff as well. Dr. Yong Wei from the University of Washington, thank you so much for being with us today. Thank you for having me.