This is my favorite Oregon beach town and every hotel I've ever stayed in there would be inundated in a Cascadia Subduction Zone tsunami scenario.

The link below is to a Cannon Beach brochure that I think is well done. Sobering, for sure.

http://www.oregongeology.org/pubs/tsubrochures/CannonEvac.pdf



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For what wave heights is the brochure modeled? That is probably stated somewhere in the text, but I am very slow at reading upside down.....

Dagny,
Though I haven't passed though there for at least a decade, my recollection is that Cannon Beach is indeed a very nice little town. However, as your link idicates, it is seriously threatened by a Cascadia Tsunami. For more information (to make you even more paranoid), you might want to read Sandi Doughton's book "Full Rip 9.0: The Next Big Earthquake in the Pacific Northwest". In one chapter she talks with a local emergency services person about the tsunami risk at Cannon Beach. To quote from a review in the Oregonian:
If you enjoy hiking, and haven't already done it, I would recommend next time you visit Cannon Beach you make the hike up to the top of Tillamook Head. It is a very pleaseant walk, and far above the ocean on the top of Tillamook Head would be an excellent point from which to view an incoming tsunami.

"20-65 feet at the shoreline" is the only wave height mentioned. It is in the upside down section.

Knowing the location of, and routes to, high ground is a pretty good idea for anyone near the sea, especially on the earthquake prone West Coast - nothing all that incredibly unique about Cannon Beach.

Well, there are a number of specific issues for places like Cannon Beach and Seaside in Oregon, and Long Beach in Washington.

Unlike, Socal, the coast of BC, Washington, Oregon, and the northernmost portion of California have a significant risk of locally generated tsunamis. If the Cascadia Subduction Zone generates a 9.0 earthquake, there would be as little as 15 minutes time before a huge tsunami struck. Some places, such as Long Beach, and Seaside have a significant distance to travel (on the order of a mile for Seaside, and several miles for Long Beach) before reaching safe ground. An earthquake that generates a major local tsunami would also do major damage, and destroy many roads, sidewalks, bridges, etc. Traveling a mile or more in 15 minutes over severely disrupted ground could be problematic for many people. And if it happened at night.......

Specifically with regards to Cannon Beach, for much of the town one must cross Ecola Creek, which is spanned by only two rather old bridges. In particular, the only practical escape route for students in the school is across one of those bridges. According to Sandi Doughton's book (mentioned up thread), that bridge is considered to be very unlikely to survive the earthquake.

You are correct that knowing the best routes to high ground is a good idea in any coastal area. However, some coastal areas are more dangerous than others, with a greater danger from tsunamis, and a longer route to escape.

Earthquakes happen, and somewhat unpredictably. I am mindful of a locally generated quake in 1812, with an epicenter in the Santa Barbara Channel, that sent a wave to the steps of the Santa Barbara Mission. At that time, there was no warning at all. The scars from that event are still plainly evident on Santa Rosa Island, and probably elsewhere.

The inundation profile for Cannon Beach is very similar to our local map with large incursions up the Ventura River and the Santa Clara River, very likely severing highway 101. Probably the main solace is that current theory predicts that our locally generated quakes will be nowhere near the magnitude of the Really Big One anticipated in Cascadia.

One other difference between Socal and the PNW is that the risk of earthquakes in Socal has been known for much longer (eg. since at least 1812 in Santa Barbara). Thus building and construction codes have been overall somewhat better. ( I am aware that this is not universally true even in Socal.)

In the PNW, the recognition that the area is subject to even bigger quakes than California has only come in the last decade or so. As a consequence, most of the critical infrastructure in the PNW was not built with any thought whatsoever of withstanding an earthquake. The Japanese quake was a real wakeup call for the PNW. Of any country in the world, Japan was probably the most prepared for earthquakes and tsunamis. The PNW is nowhere near as ready.

I grew up in a beach town, literally feet above sea level. The 1938 hurricane had a major impact on my hometown, creating a salt water pond where the day before houses stood. It's a fact of life that at some point in time, all coastal areas will be affected by some nature related incident.

Accept the risks. Plan for them.

Yes, we accept the risks and plan for them. One big difference between tsunamis and hurricanes is the amount of warning. With hurricanes, one knows the season when they generally occur. If one wanted, one could even arrange to make a trip to Wyoming during hurricane season. And for each hurricane during the season, one generally has days of warning. That gives ample time to prepare, and make a choice about evacuating or staying.

Tsunamis are much less frequent events than hurricanes. Unlike hurricanes, tsunamis are not seasonal. Most significantly, tsunamis occur suddenly, and one has at most a few hours of warning for a tsunami generated from a distant earthquake. For a tsunami generated by a local earthquake the warning time to evacualte is only minutes. Also, a local earthquake which generates a tsunami will also most likely do significant damage to the very roads, bridges, etc which one would want to use to evacuate.

Thus, while it is easy to just say "Accept the risks. Plan for them.", it is a rather different problem, and in some ways a more challenging one than planning for a hurricane.

probably the most important map in the USA right now.
but it's a real mood killer for the honeymoon :-)

Pete2

AKSAR -- thank you for this recommendation. It was probably your mention of this book last summer which caused me to read it (fascinating). I bought my sister a copy and she devoured it. She lives in Portland and frequently vacations at Cannon Beach.

So thanks for the recommendation -- that is an excellent book and it made a big impression on my sister. We were discussing it the other night and reminisced about how we both went to Oregon State University in the early-mid 80s before the public knew anything about the subduction zone threat and geologists were still debating it.

We spent dozens of weekends at the beach (Newport, an hour from Corvallis) and had no inkling of the threat. If I'd felt an earthquake back then of any size I'd have been surprised. Would have had absolutely no sense of urgency to get to higher ground to avoid a tsunami.



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As of this summer, the state has finished mapping the entire coast for the tsunami threat. 300-mile long coastline.

http://www.oregongeology.org/pubs/fs/TIM-maps-factsheet.pdf


If you know anyone who lives or vacations on the Oregon coast, here's an app (there's also one for other smart phones):

https://itunes.apple.com/us/app/tsunamievac-nw/id478984841?mt=8



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