a tsunami defense mechanism

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A Tsunami Defense Mechanism

Introduction - The thinking behind this concept

Vancouver

The potential devastation a tsunami would create in the Vancouver area and the Lower Mainland is enormous, to the point of creating a national disaster for

Canada. As such we must think in terms of protecting the population, buildings and infrastructures in the Lower Mainland at reasonable costs to help control

the source of possible destruction. In the event of a major tsunami, it is out of the question to evacuate in time up to one million people from the most

vulnerable areas. Thus this project gives an alternative to the prospect of major destruction in the city and its people.

Contrary to other tsunami defence mechanism which consists mainly of solid walls of diffrent materials and shapes, this proposal aims at creating a series of movable

gates that could be raised up a few meters above high tide sea level. The movable gates would neither obstruct passages to ships nor interfere with water flow or sea life

under normal condition but would be in full force pending a tsunami alert. The main principle is to break the tsunami waves well before they reach the shores by acting as

buffers and deflectors.

Made of horizontal panels supported by pillars inserted in the bedrock (seefloor) this moving structure would sit at the bottom of the sea during normal period but would be

raised up if a tsunami alert is triggered. Insertion of pillars into the sea floor at a certain distance from one another would insure the stability of the structure at high waterpressure level. These posts would act as support structures for the movable gates to be raised in place and act as buffers against incoming upsurge of water. Since it is

not a solid wall but rather a semi-wall it would still allow the water to flow through but at a diminished speed and force. In that sense two barriers at a distance equivalent to

the wavelength of a tsunami wave - in the range of a few hundred meters from each other - are of the utmost importance. Only this would allow for an efficient buffering

and breaking ot such waves. As we know the dynamics of tsunami waves which are moving through pressure reach for the most remote inner landscapes of a coast such

as inlets, fjords, bays and the like. This tusnami defense mechanism should then be erected to deflect the water from entering these areas by artificially providing an

alternative route for the flow of waters.

October 2011

Marc Bdard Pelchat

Qubec Canada G6B 2J2

+1.819.582.2365

This is a website in pdf. Original is here: http://palomar.hostultra.com/tsunami/


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involved our neighbour to the south (the State of Washington, the US government) in embarking in such a project.

In the case of a strong tsunami, most of the area south would suffer considerable damage to perhaps the point of being wiped-out since the waters could reach deeply

inland, not unlike Sendai, Japan in March 2011 or Banda Aceh, Indonesia, in December 2004.

Another possibility which is based on the idea of a comprehensive project would be to erect the barrier from West Vancouver to Tsawwassen and further, eventually evencovering the Bundary Bay. This has certainly the most certain safety aspect that the two preceeding phases would not have since it would skip the complicated interchange

at the UBC level between phase one and two, considering the c liff of UBC acting as a buffer zone is not warranted, since the soil composition in this area doesn't allow for

much resistance to major tsunami waves.


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From Locarno Beach, the raised barriers, invisible otherwise except for the pillars.

The idea behind the structure consists in allowing the f low of water, for it would be all but impossible to stop the surge of incoming water f rom a tsunami, yet it is feasible to

diminish its intensity and deflect or redirect the waves. The basic characteristic of the structure employs buffering as the means to control the flow of water so it does not

come as strong on the shores. The venetian blinds is a good example of the type of structure at work here.


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Figure 5 shows the process of either raising up our down a mechanism that would act as a barrier to slow considerably the surge of water of a tsunami force sea. The

comparison to venetian blind is approximative but gives a good idea of the way the mechanism would work.


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Published: ~ v e m b e t 2. 2011 ::# TWITTER 1m LINKEDIN 181 SIGN IN TO E-MAIL EJ SHAREA Tsunami Defense Under ScrutinyJ apanese authoritieshave decided to rebuild a $1.6 billion breakwater in Kamaishi, a city of fewer than 4o,oo o people, even though experts are dividedover whether it was effective in protecting agains t the tsunami that hi t J apan on March 11. Related Article

KAMAISHI RYO ISHI ~ _ /Approx. pre-tsunami population: 600; 45 dead ~pprox. pre-tsunami pcpulation: 39,600; 935 deadThe average wave height registered was 29 feet. The average wave height registered was 65 feet. ~ Kamaishi Area ftooded anerthe tsunami

Effect in neighboring townsOriginal designers of the breakwater, which took 30 years tocomplete, worried that it would increase tsunami waves and redirectthem toward Ryoishi and Kariyado, which were destroyed by wavestwice the heigh t of those tha t landed in Kamaishi.

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~;r-. 400 MILES

Tsunami heigh tMaximum height ofwatermarks left bytsunami inundation at 101points along the

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27 houses;5 deadAverage waveheightof 62 feet.

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Scale model

In this case as in any other a scale-model of the workings of this tsunami defense mechanism would have to be built. Only it could determine if the

resoning about this concept makes it and gives the results hoped for. A tsunami scaled-model was made to see how a tsunami would hit a coastal town,Seaside, Oregon. In a CBC documentary - Shock Wave - this experiment was shown in this 90 minutes long film which takes a look a the devastationtriggered by tsunami waves.

Shock Wave, CBC Television, December 27, 2009

Conclusion

Although this presentation has its flaws, it should not be dismissed right off for that reason. In the realm of proposals anything goes! Considering thechances of a tsunami of great strength anywhere in the Pacific Rim, we should take all the ideas out there and make an assesment of their workability.

The end result could be the safety of millions of people. As we discovered with the December 26, 2004 tsunami in part of the south Asian and Indiansubcontinent coasts, mangroves would play a great roles in some areas where the have been preserved. Mangroves are hardly concrete walls but theyhelped in slowing down the incoming tsunami wave. All coasts can't be restored with mangrove barriers or they would not grow everywhere in any case.

Thus this proposal takes into account this reality and offer a man-made barrier that is both financiallly, physically feasible and could mean the differencebetween total destruction of territories, structures and people. In that sense it is worth spending some time and money to verify its potential which is notof my reach. Considering the staggering high cost of a concrete barrier in the Kamaichi Bay (1,6 billions dollars), this proposal at least has the merit to

cost a small fraction of this and could prove to be way more efficient.
http://maps.google.ca/maps?q=Seaside,+OR,+United+States&hl=en&ll=45.993145,-123.922606&spn=0.008453,0.021136&sll=49.891235,-97.15369&sspn=32.227455,86.572266&oq=seaside&vpsrc=6&hnear=Seaside,+Clatsop,+Oregon,+United+States&t=h&z=16&source=gplus-ogsbhttp://maps.google.ca/maps?q=Seaside,+OR,+United+States&hl=en&ll=45.993145,-123.922606&spn=0.008453,0.021136&sll=49.891235,-97.15369&sspn=32.227455,86.572266&oq=seaside&vpsrc=6&hnear=Seaside,+Clatsop,+Oregon,+United+States&t=h&z=16&source=gplus-ogsbhttp://www.cbc.ca/documentaries/doczone/2009/shockwave/http://www.cbc.ca/documentaries/doczone/2009/shockwave/http://maps.google.ca/maps?q=Seaside,+OR,+United+States&hl=en&ll=45.993145,-123.922606&spn=0.008453,0.021136&sll=49.891235,-97.15369&sspn=32.227455,86.572266&oq=seaside&vpsrc=6&hnear=Seaside,+Clatsop,+Oregon,+United+States&t=h&z=16&source=gplus-ogsbhttp://www.cbc.ca/documentaries/doczone/2009/shockwave/

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