Earthquakes and/or tsunamis in Pac. NW

[El and Bill]

We have discussed this with Brats in the past. Here is a recent article on the subject.
Do you know how to react if you receive a warning about a tsunami if you are on your boat or at the dock? What about a warning of seismic waves you receive at home, or work or shopping?

Do your kids know what to do if their school gets a warning?

As a geologist who studied geologic threats and advised the Civil Defense, take some advice: Be prepared.

http://www.newyorker.com/magazine/2015/ ... ly-big-one


[/list]

 

[El and Bill]

A follow up from the Seattle Times:


http://www.seattletimes.com/seattle-new ... read-this/

 

[hardee]

Thanks Bill,

I guess I would hope to be on tha boat and about half way across Juan de Fuca... deep water and far away from shore.

Harvey
SleepyC :moon

 

[rogerbum]

Thanks Bill,

I guess I would hope to be on tha boat and about half way across Juan de Fuca... deep water and far away from shore.

Harvey
SleepyC :moon

And assuming that works OK for short term survival, where do you go next? The marina is toast, there's no fuel available on the water miles. There are no docks remaining for miles... 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.

 

[thataway]

Thank you Bill. Certainly gives one pause! Not even a C Dory would save your life in that scenario!

If the falling structure does not kill you, the Tidal Wave will!

 

[Hunkydory]

Tidal waves, as I thought of them as a kid were a reoccurring nightmare for me that receded as I aged, but still linger in my thoughts, especially while being on a cruise like at the present time. The catch 22 when at anchor or dock is whether to head to deep water or high ground with decision time short & a very good likely hood of being caught in between, so for the most part in order to get a relaxing & restful night, I prefer to think of other more pleasant things knowing the odds are very small that this will be the night of the big one.

Jay

 

[AstoriaDave]

The New Yorker article Bill referenced http://www.newyorker.com/magazine/2015/ ... ly-big-one is exceptionally well done. I live at the mouth of the Columbia, but above the inundation zone. Woe to the several thousand Clatsop County residents and visitors who might be west of the chokepoints if the very big one hits. There is a strong element of avoidance here, with motel owners concealing brochures detailing tsunami escape routes, and voters shunning spending the bucks to re-site schools outside the inundation zones.

Our surface geology is a disturbing mix of clay soils and old slide zones, with the odd basalt hard point here and there within the Astoria city limits. I would guess something like 80 per cent of the structures here will be uninhabitable after all is said and done. Good thing we own a lot of camping gear and food.

 

[hardee]

Thanks Bill,

I guess I would hope to be on tha boat and about half way across Juan de Fuca... deep water and far away from shore.

Harvey
SleepyC :moon

And assuming that works OK for short term survival, where do you go next? The marina is toast, there's no fuel available on the water miles. There are no docks remaining for miles... 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.

Roger,

Good question -- bad thoughts :roll: My basic thought is that in the area there are some pretty significant, bays and inlets, so I am thinking that there would be some lee shore somewhere. There are options for beaching or landing without a dock. One of the advantages of a small trailerable. As to fuel and facilities, that will obviously depend on numerous things, Strength, depth, duration and distance from epicenter.

I guess I would not want to be on the elevated 99 going through downtown Seattle NOR would I wnat to be in a tunnel, below sea level, going through (make that UNDER downtown Seattle.) I guess if I'm on land, I;m hoping for going around a traffic circle in Sequim :wink:

Harvey
SleepyC :moon

 

[starcrafttom]

Bill please tell me if you think that this would have that big of a impact in the sound as the news is saying. I read part of the report that made all of this news earlier in the week and it stated that the the tsunami would not really reach settle at all. 1 to 3 ft tide surge. Who could "every thing west of I - 5 be destroyed, as the news has been claiming all week, because by a 3 foot tide? I know the coast would be toast but really that much damage from a quake 300 mile or so off shore?/ ( cant remember the distance but it was around that)

Also the quake in japan did not cause very much damage its self. Mostly the water caused the damage, of I am I wrong about that? I just find the idea that "everything west of I 5 will be gone" is a huge over statement when the vast majoriy of land west of 5 is over 100 ft to 8000 ft above sea level?? I live less then 3 miles from the sound at 300 ft above sea level. id this really a story or just news bull shit??

 

[thataway]

In partial answer to what to do to survive, if you go to sea in your boat.
It would be far better to stay on the boat, and hope to have enough survival food and water for at least a week. I would suspect that there might be other tsunami with after shocks--especially with a earthquake of this magnitude.

As the water recedes, you may be able to find a place where you could eventually make land--but you would want to be safe in the mean time. At sea, the tsunami is a non event. I have taken my boats to sea in S. Calif. several times during the last 50 years, but the tidal range was only 6 or so feet with the events, from many thousands of miles away.

 

[AstoriaDave]

Tom, that statement about the area west of I-5 was directed at Oregon, if I recall the article correctly. Not Puget Sound. Yes, there is some exaggeration there. The damage from a magnitude 9 quake to structures not built to withstand the shaking is horrendous. I suspect that is what they mean. I am well west of 5, here in Astoria in a 2000 vintage 3 BR 2BA home on a standard foundation, built to the 1995 earthquake protection specs. I think it will still be attached to the foundstion when things quit moving, but unsure whether I will have much structural integrity ... or whether the roof will still keep the rain out. Further, the clay soils here, combined with old slide zones make it likely the house will at least partly be in somebody else's back yard.

All this, and I am 100 feet above Youngs Bay, inside the raws of the jetty 10 miles or more, so the tsunami won't reach me. Earth movement is whst will do the most damage.

Damage to roadways and other elements of infrastructure will be enormous, making it necessary to tough it out for perhaps a couple weeks or more before anyone can reach us, even here in town. I expect to have to protect my food and water, and have made preparations for that. My family built a fallout shelter in 1961, and worked through the post nuclear attack scenario. This wil be easier, I believe.

 

[aneed]

Now that I live in very dry Idaho, all I apparently need to worry about is Yellowstone. If is "blows" I'm a goner! :roll:







Deena McDaniel
former owner
CD 22
"Sleepy C"

 

[smckean (Tosca)]

I think the 3 foot tide danger is not so much about the height (altho total height is vital of course), but the speed at which this "tide" approaches. From slack to high tide takes what 3 hours? With a tidal wave, this happens in a minute or two. The result is more like a river sweeping all before it. It ain't the water itself so much that is a danger, as it is the debris in the water (coming at you rather swiftly).

I was living in the Marina in San Francisco when the 1989 earthquake hit. We were at home, and our block was just about the worst damage area in the city. Some experience I can tell you! We laid low in our home for 6 days while the police cordoned off our entire neighborhood. I have lots I could tell, but suffice it to say, the #1 thing I learned was that the most important thing is having water....especially drinking water.

 

[Da Nag]

I read part of the report that made all of this news earlier in the week and it stated that the the tsunami would not really reach settle at all. 1 to 3 ft tide surge. Who could "every thing west of I - 5 be destroyed, as the news has been claiming all week, because by a 3 foot tide? I know the coast would be toast but really that much damage from a quake 300 mile or so off shore?/ ( cant remember the distance but it was around that)

Grossly oversimplified, but that's more or less the consensus of three WA geologists who just answered a bunch of questions over at reddit on this topic.

Basically, they said the west side of Whidbey could suffer significant damage - but that prepping for tsunami damage anywhere else other than coastal areas was a fool's game.

The vast majority of damage and loss of life will be from toppling buildings - both Portland and Seattle have tons of structures similar to those that have fallen in CA quakes. Portland in particular, didn't even incorporate seismic specific building codes until the late 80's. Combined with a lack of significant shakers in recent years, the PNW has a much higher percentage of structures that are vulnerable than CA.

Water damage from liquefaction of soils will also be far more extensive than any tsunami damage in these areas.

Their advice was similar to that being offered in this thread. First priority - have a minimum of 7-10 days supply of food, water and gas on hand. Second - invest in securing susceptible homes to foundations, which for wood frame construction built before the 80's is relatively cheap and very effective.

 

[T.R. Bauer]

Welcome to the we are screwed when the next one hits club......My house nearly sits on the Castle Mountain Fault outside of Wasilla and it is overdue too. There won't be any waves, but it won't matter......

 

[Blueback]

Thanks Bill,

I guess I would hope to be on tha boat and about half way across Juan de Fuca... deep water and far away from shore.

Harvey
SleepyC :moon

Harvey,
I can tell you a story here of my direct experience with a tidal wave (tsunami).
In 1964 there was a massive earth quake in Anchorage Alaska: C &P quotes here---"On March 27, 1964, at 5:36 p.m. ADT (03:36 3/28 UTC) a great earthquake of magnitude 9.2 (moment magnitude) occurred in Prince William Sound region of Alaska. The epicenter was about 10 km east of the mouth of College Fiord, approximately 90 km west of Valdez and 120 km east of Anchorage. The epicenter was located at Lat. 61.04N, Lon. 147.73W, at a depth of approximately 25 km. This earthquake is the second largest earthquake ever recorded in the world. after a M9.5 earthquake in Chile in 1960. The duration of rupture lasted approximately 4 minutes (240 second
Much of the damage and most of the lives lost were due to the effects of water waves. These were mainly of two kinds: the tsunami of open-ocean sea wave, generated by large-scale motion of the sea floor; and the local wave, generated by underwater landslides in bays of fiords.
The 1964 Alaska tsunami was the second largest ever recorded, again following only the one caused by the 1960 Chile earthquake (4 meters at Sitka). Of the 119 deaths attributable to the effects of the ocean, about one-third were due to the open-ocean tsunami: 4 at Newport Beach, Oregon; 12 at Crescent City, California; and about 21 in Alaska. Local waves claimed at least 82 lives. Maximum height reported for these waves were 70 meters in Valdez Arm".
On that day I was serving as a Marine Eng. on the Canadian coastal passenger and supply ship "SS Canadian Prince". We were north of Prince Rupert by about 20 miles and making a turn to enter the harbour of Port Simpson. I was the watch engineer at that time and the movement of the engine plates indicated flat calm sea conditions. I was always warned from the bridge if heavy wave action was about to start so that I could instruct engine-room staff -and act myself to secure loose gear 'heavy wenches" etc.
Out the blue the ship heeled over to about 15 degrees and some metal objects in the engine room were airborne. That was it "one wave"? I phoned the bridge and said - "what the hell happen"? Their answer was -- "no idea - one wave came at lightning speed out of the NW"? About an hour later we heard the news of the massive earth quake in Alaska-- then later on, the news of Port Alberni, BC being smashed to hell in this tidal wave that swelled up in the Alberni Canal. A few months later I was to work as Mar. Eng. on a salvage tug bundling up tsunami-wave broken boom logs for marine transport down to Chermainus, Van. Isl's. east-coast sawmill. Now I wish I had been on deck to get a sense of the height of that tidal wave and then I might tell you Harvey -yes - or no- as to whether our great Dorys could have survived --LOL. My gut feeling is - probably not - for 2 reasons. The tsunami wave on the open ocean can travel at about 500MPH - I'm told - not high, but fast. You may be hit "unless lucky" on your beam without time to come about-- bow on -- or 2- maybe the wave would just overpower a small boat.
Something to think about ---eh
an old sea-dog --Geoff

 

[El and Bill]

Thanks for the good responses. Information is available at FEMA on line. Shake Alert is another interesting site -- the hope is to alert folks via iPhone or similar at the first shock -- seismic waves travel at different speeds -- the most destructive (usually) are slower than the initial shock, so the alert might give a (very short) time to take action. There are good proven ideas on Internet sites.
I am not trying to generate fear -- quite the opposite -- recognition and proper response for protection. The likelihood is remote in a lifetime, but possible, so be prepared.
Bill

 

[T.R. Bauer]

I'm pretty sure wave mechanics says there is little water moving in the open ocean during most tsunami events as all that is moving is incredible amounts of energy; it's been a long time since I studied such things. Yes, there will be a mega wave near shore or in fjords and canals, but out at sea it should be very long duration event and probably not even noticed in a vessel. The Strait may not be a very good place to be as it is a bottle neck that could amplify conditions - better than the marina for sure though as that is going to be a mess! I hope we never have to see it.

 

[AstoriaDave]

I'm pretty sure wave mechanics says there is little water moving in the open ocean during most tsunami events as all that is moving is incredible amounts of energy; it's been a long time since I studied such things. Yes, there will be a mega wave near shore or in fjords and canals, but out at sea it should be very long duration event and probably not even noticed in a vessel. The Strait may not be a very good place to be as it is a bottle neck that could amplify conditions - better than the marina for sure though as that is going to be a mess! I hope we never have to see it.

That is my understanding, also. Wave height very small in deep water (e.g., thousands of feet), but very long wavelength, as in many miles. As the tsunami begins to feel the bottom, approaching the continental shelf, height increases as the wave shortens. No breaking waves until shallower water is reached. The videos of the Indonesia tsunami show pangas heading out into the open ocean, and some, at least, were saved that way. Any confined, shallow waters would be a maelstrom, even behind a small island.

 

[Blueback]

I'm pretty sure wave mechanics says there is little water moving in the open ocean during most tsunami events as all that is moving is incredible amounts of energy; it's been a long time since I studied such things. Yes, there will be a mega wave near shore or in fjords and canals, but out at sea it should be very long duration event and probably not even noticed in a vessel. The Strait may not be a very good place to be as it is a bottle neck that could amplify conditions - better than the marina for sure though as that is going to be a mess! I hope we never have to see it.

That is my understanding, also. Wave height very small in deep water (e.g., thousands of feet), but very long wavelength, as in many miles. As the tsunami begins to feel the bottom, approaching the continental shelf, height increases as the wave shortens. No breaking waves until shallower water is reached. The videos of the Indonesia tsunami show pangas heading out into the open ocean, and some, at least, were saved that way. Any confined, shallow waters would be a maelstrom, even behind a small island.

If there is any doubt about what I was referencing to in my story above, the shelving up from the Pacific takes place well off shore which slow the base movement of a Tsunami and raises the wave height. I was in "relatively" shallow water. Harvey references to the Strait of Juan De Fuca -- and this area is necking down the ocean to about 20 miles wide. So let an experts tell us-- what can we expect for wave height - say off Trial Islands?