Earthquakes and/or tsunamis in Pac. NW

There are many records of small boats in deep water, at sea, during Tsunami events. As Dave and T.R. Bauer, note, there is and up and down, wave, long duration, and no breaking wave front. My only experience has been in 3,000 feet of water depth--and not noticeable.
 
I'm under the impression that the water recedes before the tsunami wave hits. You might not be able to even go out to sea if you are tied up to the dock and the marina is shallow. If the marina is deep you might just be hanging sideways if the finger pier doesn't move all the way down to the new water level.
 
Blueback,

No doubt what hit you off Port Simpson was the leading edge of the surge from that tsunami. My chart does not show depths where you were, but definitely shallower than the edge of the continental shelf. There is some confinement there, but not much funneling.

What to expect at Trial Island? I could not guess, even with depth info. The Strait shows some funneling, moving west to east, but is nowhere as confined as Alberni Inlet. AI is a dead end, and so there would be a pretty good seiche at the head, similar to what happens in a surge channel on a rocky coastline. In contrast, Trial Island is not near a confined area, which should minimize any seiche.

Here is an authoritative source of more info, with some simulations in and along the Strait.
http://www.jdfem.com/jdf-TSUNAMI.htm

Edit:

Whoa! I ran those simulations, both for the Strait, and for Victoria Harbour. I see maximum wave heights of about 200 cm, ca. 6 or 7 feet, in the Strait, but much more at the head of Victoria Harbour, for "The Big One." The tsunami surges in the Strait are spread out, and not steep. I'd guess a small vessel far from shoreline effects would be OK. In the Harbour, mayhem. Those simulations are pretty dramatic.
 
Blueback: I have no doubts to your personal experience at all. I bet it was terrifying! I prefer green grass and high tides.

In all honesty, anybody that thinks they can predict really what will happen in a horrific event like this is likely to be reaching. Nobody has any real idea what will happen as there are so many variables. No doubt it will be awful and there is no question I don't want to see it happen.
 
T.R. Bauer":kysd5ghs said:
Blueback: I have no doubts to your personal experience at all. I bet it was terrifying! I prefer green grass and high tides.

In all honesty, anybody that thinks they can predict really what will happen in a horrific event like this is likely to be reaching. Nobody has any real idea what will happen as there are so many variables. No doubt it will be awful and there is no question I don't want to see it happen.
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Amen Brother
 
I've thought a bit about what I would do if I were offshore and I don't have a good answer for how I return after the danger has passed and the damage is done.
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I'd just sit and wait for the ever efficient, caring and loving "momma", the Federal gov't to swoop in with black helos and save me.
:wink:
 
Blueback":29a96ivo said:
T.R. Bauer":29a96ivo said:
Blueback: I have no doubts to your personal experience at all. I bet it was terrifying! I prefer green grass and high tides.

In all honesty, anybody that thinks they can predict really what will happen in a horrific event like this is likely to be reaching. Nobody has any real idea what will happen as there are so many variables. No doubt it will be awful and there is no question I don't want to see it happen.
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Amen Brother
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I second this.
 
Dave mentions the word "seiche". Which can occur during a Tsunami, but often is an independent oscillation of a standing wave, and may occur in both enclosed systems (Lakes) or partly open systems, such as a narrow harbor or fjord.

We had just visited the village in the long narrow harbor at Clutadella on the Island of Minorca, and were anchored less than 75 miles away in an open harbor of the Island Majorica.

A day after our visit a seiche occurred. (locally called a " rissaga ". There was extensive damage to the harbor and boats. This particular bay has these seiches without warning. periodically during recorded history! We would have had severe damage to our boat if we had still been there. These appear to be the result to certain tidal variations, not any known tectonic plate activity.

For a very technical explanation of the "seiche" see:

http://www.pac.dfo-mpo.gc.ca/science/oc ... apter9.pdf

Near the end is a photo of Clutadella on June 24, 1984.
 
Hay Brats,
Here in the inland PNW we have a lot of houses for sale 3 Good lakes and a river, three people at a intersection is a traffic jam and the ground does not shake. The way last winter was no winter.

Guy
 
If an earthquake does occur off the coast of Washington and the wave enters the Strait of Juan de Fuca, how do the effects translate into the San Juan Islands say thru Cattle Pass or up Rosario Strait into Lopez Pass or Thatcher Pass?
 
My town was recently certified as "Tsunami Ready." We have an early warning siren that goes off every weds at noon, and have signage all over town.

There is boat space for everyone in town probably, but up the hill is the only call for us. If I was on my boat I would get to shore and get up a hill also. In the nearshore area I am, I can't reliably get to open water.

But, we have a lot of shallow water near town. In 1964, the water moved in and out very slowly here, but in towns with deep water close by, there was devastation. Cordova was a sanctuary where a lot of people came from Valdez, Tatitlek, and Chenega. Many are still here. those towns were devastated, as was Anchorage.

We take it very seriously, our phones alert us to earthquakes, and more than once we have gotten up in the middle of the night after a quake nearby, and prepared to go uphill. We have never made an actual exodus, but we actively decide to stay put.

A lot of the low lying areas around the City are fill, which would likely liquify in an earthquake, including our hospital. I'm more concerned about that impact locally, than I am a tsunami. But that is just for this particular spot.
 
The New Yorker article and spinoffs, as well as the simulations Joe references, stimulated a lot of discussion and debate among the earthquake/tsunami preparedness folks in this coastal community ... and amongst ordinary Joes and Janes.

We live on the tines of the fork.

Are we panicked? Frothing at the mouth? Rushing to sell our homes? Hell, no!

Most of us knew, or grew to know, that living on the coast exposes us to action from tsunamis and subduction zone earthquakes which have the POTENTIAL to cause havoc and serious turmoil. And, we have accepted that. We would rather live our lives on the edge .. of the continent .. enjoying all of its benefits while preparing as we best can for what MAY come in our lifetimes.

After that, it is business as usual. And, we will try to scratch up the dough to resite the schools our kids are in out of high hazard areas. Kind of a shame to snuff out a young life because those of us near the end of our God given span can't share a reasonable amount of money to protect those kids.
 
Gene&Mary":1etbr183 said:
If an earthquake does occur off the coast of Washington and the wave enters the Strait of Juan de Fuca, how do the effects translate into the San Juan Islands say thru Cattle Pass or up Rosario Strait into Lopez Pass or Thatcher Pass?
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Joe reposted that tsunami simulation, which shows the passage of successive tsunami surges through the area which interests you.

Clue in on the red, which identifies the roughly six foot tall, long wave surges, and note where they seem to intensify (red gets redder and darker). And, where they do not intensify (less red). The former would be areas of greater flow and turbulence. The latter, lesser currents and turbulence.

Then relax.

You would have to be really unlucky, in the typical cruise in the San Juans, to be in one of the higher hazard areas at just the wrong time ... particularly because you have an hour or so of warning before the front of the tsunami enters the San Juans after your VHF goes nuts with warnings of tsunami activity to the west, beginning at Neah Bay. In the open, deeper water to the north of the San Juans and away from confined areas or shallow depths, these surges should be much less intense.

The hazard is extremely remote. You should have enough warning to get out of fhe archipelago if you need to. You'll have lots of company, also.
 
The hazard cruising in the San Juans, or living in the islands, is not just an earthquake offshore to the west and a tsunami coming through the Strait --
There are faults zones that cross the islands that have generated earthquakes or tsunamis in the past. The Dept of Emergency info site below gives good info.

This is not to alarm -- just to be knowledgeable and prepared. There IS a risk. Bill F.

joomla.sanjuandem.net
 
The Japan tsunami caused millions of dollars of damage to our harbor in Crescent City. It was rebuilt to withstand larger tsunami's but not the big one. We had engineers and harbor personal in the harbor that day. Scientific studies. They were lucky that the wave did not spill out of the harbor.

The day of the Tsunami I wandered out to Point St George. It was 9 hours after the first wave hit. In less than an hour I witnessed a low tide, hide tide lapping the grass on the hillside and another low tide. Things no longer go by tide books for a while.

We have mountains within 15 minutes if roads are operational. I would count on a traffic jam and try different paths (Past experience). You would be one of the lucky ones if you made it out. Its going to be a mess. I think in our area a wave could come from the harbor and sweep the mountains all the way to Smith River. Most all developed property in the area would be lost. That includes my residence that is 4 miles from the harbor.

Our area seems to attract the tsunami's due to Point St George and the big catchers mitt South Beach. I do not intend to move. Hopefully we can ride it out.
 
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