The lessons of Sendai

[Don Hudson]

For my fellow Vancouverites:

Under the heading of awareness, but not intending to needlessly worry, here are some thoughts on the Sendai event, the Japanese experience, and Vancouver.

We continue to acknowledge the eventuality of "the big one" but how many in the Vancouver area have Go Kits in cars and in homes?

How many have discussed actions to take in the first thirty seconds of a major earthquake?

How many have prepared plans for the days following the earthquake and tsunami to survive, communicate and regroup?

How many can claim to have done that with their families since Haiti?..since New Zealand, or now?

These are actions which no government or agency can take for us. They are ours alone to take. Government can prepare through infrastructure; we prepare through awareness and planning. There are plenty of guidelines and action plans on the internet available to assist.

Last week, at tragic and as-yet untold cost, we were provided with the information needed for defensive action on two fronts earthquake and tsunami. Through tragic example, we know what will, at some point, occur here, and that it will not likely be earthquake alone.

The Japanese experience has many lessons for North Americans living on the west coast who may believe that it is only the shaking that does damage in an earthquake and that preparations have already been made in Vancouver for quakes approaching the magnitude of the Sendai one.

I do not think Vancouver is prepared, materially, administratively or psychologically for the possibility of tsunami after the big one.

As a friend with whom I regularly communicate on these and other matters has observed, after the disastrous tsunami which resulted from the Alaskan earthquake of 1964 and caused signficant damage on the west coast of Vancouver Island, has the city of Port Alberni, at the end of a long fiord, even installed public tsunami warnings or loud speakers?

The illusion may be that a tsunami is not expected in the Lower Mainland because Vancouver Island is in the way. We have heard this kind of analysis as early as this week.

I think that that is a risky assessment.

Vancouverites should not expect that Vancouver Island will shield them from any such event because the interface between the east-moving subducting plate moving under the west-moving North American plate lies underneath an area from the same distance offshore as the Sendai quake, (230km), to the interior of British Columbia/eastern Washington, although obviously deeper the further inland one is. Quakes can and have occurred east of Vancouver Island.

A tsunami results from a sudden uplift of the ocean floor. The Sendai earthquake produced a sea-bed uplift of about 50ft. Because water is incompressible, the displacement instantly produces a local hydraulic lift which, due to incompressibility, extends immediately to the surface, raising the surface height of the water in the area of the event. Since water always seeks its own level, the local rise in sea level will then immediately sink, transmitting the huge energy resident in the "head of water" into a wave, moving out from the event at about 800km/hr. In combination with height produced by the original seismic event, the resulting momentum of hundreds of square kilometres of sea-water is, as the Sendai event has shown, unstoppable.

We may debate the potential height of any tsunami but we know how such events are generated. We must assume that the Georgia Strait is as capable of producing a tsunami just as the Pacific is capable west of Vancouver Island.

Vancouverites think of Vancouver Island as one large, natural barrier to a tsunami. It is demonstrable that this thinking, which ostensibly neutralizes a defensive mindset and supplies a false sense of security and preparedness, is a mistake. A tsunami for Vancouver is possible if the center of the quake is in the vicinity of Georgia Strait where a number of fault lines exist and not necessarily beyond the shores of Vancouver Island.

The Japanese experience therefore has lessons for us. Their high seawalls were not sufficient. Their experience shows that Vancouver may well suffer far in excess of the worst scenarios imagined and those preparatory documents written as a formal basis for present preparations. It is not only the shaking or (Richmond) liquefaction which must be addressed. We have the same problems to address as did Sendai and Los Angeles in terms of a tsunami and flat ground.

Let us consider what areas would be underwater with raised sea levels. These are the areas which are at greatest risk of the kind of destruction seen at Sendai.

On a cursory inspection and from having lived in the Vancouver area most of my life, I think it is plausible to assume first, that Tsawwassen would temporarily become an island. In such a scenario, food and water for a sustained length of time would be a consideration as delivery of same could be restricted due to damage and debris on the roads connecting Vancouver and the south; South Surrey/White Rock would be an long isthmus as water extends over the farmlands to the north and to the east just short of Langley and northeast to the flats south of Port Kells as the sea-level rose above the low-lying farming areas to the north and east of both areas. Roads to the east and south near the Canada/US border would be open as the water would not extend that far inland (in a six-meter wave).

Panorama Ridge/Delta would temporarily become an island though with a narrow connection to the mainland possible on the north. North of Tsawwassen, Richmond, Vancouver Airport and all land adjacent to the Fraser River delta would be under water. The Marpole area and east along Marine Drive would be the first visible land north of Tsawwassen and White Rock. Vancouver Airport would look like Sendai Airport, perhaps worse given the absence of any protection to its west. The many substantial log-booms on the north arm of the Fraser would become projectiles carried ahead of the wave. Coal Harbour would extend parallel to Terminal just short of Clark, and, with enough energy, north along Main to Burrard Inlet. Stanley Park would become another temporary island Vancouver could, depending upon the height rise.

....(section discussing Los Angeles basin removed)

Google Earth has a model of rising sea levels using the global warming scenario, but it is just as applicable to a tsunami-type event…what is different is the time period and of course the relative impermanence of the sea level. As a basic exercise, one can mouse-over each area of interest in G.E. to see that areas height above sea level.

The notion of rising sea levels due to global warming is nevertheless useful in analyzing what a temporary rise in sea levels would look like which helps us imagine the extent of damage so that these events may be more clearly anticipated.

The Sierra Club has posted the elementary graphic displayed below as one guess at what a six-meter rise would look like. Google Earth has a scenario for San Francisco but I cant find one for Vancouver. It would be a good iApp for someone with the programming talent, time and motivation…someone from here...

The greatest hindrance to effective and efficient planning for these kinds of scenarios is our unlimited capacity for denial. I think the Japanese event may help overcome some of this but denial is a powerful thing. This note is a call to thinking and planning. As Richard Feynman observed while writing his section of the Report on the Shuttle Challenger accident which he considered eminently preventable, For a successful technology, reality must take precedence over public relations, for Nature cannot be fooled.

Don

Edited to remove section on Los Angeles

[melcrothers]

We used to live in Ladner just a block from the docks and I remember going to a public "awareness" session in 1998-9. With the Delta, the shocking thing was how we would end up dissapearing into the sand and mud and they expected us to drop 10-15m minimum. If YVR had an 8.9 we would have been buried alive.

Mel

[sustainable]

Don, not to take anything away from your usual thoughtful and insightful prose but a minor correction, LAX is 125' ASL with a fairly steep and substantial bluff separating it from the ocean. True the bluff may be formed from the same "snot rock" that underlies the rest of the basin but I think a tsunami would have a hard time broaching it. OTOH, the belief I held that the Juan de Fuca Strait would dissipate some of a tsunami's force, the evidence from Japan's East coast seems to show that narrows concentrated the waves allowing their propagation farther up the surrounding slopes.

[Don Hudson]

Don, not to take anything away from your usual thoughtful and insightful prose but a minor correction, LAX is 125' ASL with a fairly steep and substantial bluff separating it from the ocean. True the bluff may be formed from the same "snot rock" that underlies the rest of the basin but I think a tsunami would have a hard time broaching it. OTOH, the belief I held that the Juan de Fuca Strait would dissipate some of a tsunami's force, the evidence from Japan's East coast seems to show that narrows concentrated the waves allowing their propagation farther up the surrounding slopes.

sustainable;

Thanks!...I didn't "know" the LAX area as well as I thought! Using the Google Earth technique (mousing over the area), I can see that there is a substantial height just inland of the beaches of about 100+ ft, which then slopes down slightly. Removed the section, anyway.

The actual scenario is one which I had read in my research and from my distant memory on layovers while flying the A320 and walking the beach was of a pretty flat area so I appreciate your correction. A tsunami of moderate proportions would likely have trouble over a "berm" that high, so I'll go back to the original article.

The "narrows" illustrates Mr. Bernoulli's principle. Unlike people, molecules (and cattle, for some odd reason) "know" that for the same flow rate to obtain, one must "speed up", not slow down through a narrowing outlet. For my simple approach, it's explained quite well in Wiki, although I'm sure cattle don't follow the same principle!...:

"Bernoulli's principle can be derived from the principle of conservation of energy. This states that, in a steady flow, the sum of all forms of mechanical energy in a fluid along a streamline is the same at all points on that streamline. This requires that the sum of kinetic energy and potential energy remain constant. If the fluid is flowing out of a reservoir the sum of all forms of energy is the same on all streamlines because in a reservoir the energy per unit mass (the sum of pressure and gravitational potential ρ g h) is the same everywhere.[4]

Fluid particles are subject only to pressure and their own weight. If a fluid is flowing horizontally and along a section of a streamline, where the speed increases it can only be because the fluid on that section has moved from a region of higher pressure to a region of lower pressure; and if its speed decreases, it can only be because it has moved from a region of lower pressure to a region of higher pressure. Consequently, within a fluid flowing horizontally, the highest speed occurs where the pressure is lowest, and the lowest speed occurs where the pressure is highest."

The "Prepare Now for an Earthquake in British Columbia" pamphlet is very good and is located here.

Don

Edited to insert link to B.C. Earthquake pamphlet

[Specs]

Whatever plans you make, you need to stipulate the premise upon which they're built and appreciate the limitaions of them. The best of plans always fall apart once a stipulated condition is breached.

Teachers in Sendai sent kids home when the alarms went off per their emergency training. Those homes were then swept away. The plan also sent citizens to community gathering places when the alarms sounded - those places were also swept away.

In YVR - the one that seems front and centre is that the emer exit routes would be clogged in minutes. A single accident would shut things down. Then what?

[Spinnaker]

The trick to living in Ladner is being close to the marina....

(I like it here too much to leave)

[CanadaEH]

Or what if a bridge or the Massey Tunnel fails? There are far too many points that could cause traffic chaos in YVR.

[nozel]

High ground out of Ladner is 5~10 minutes to Tsawwassen, 15~20 to North Delta under IDEAL ROAD CONDITIONS.

After an earth quake of 8+, those conditions would not... If I was unlucky enough to be caught at home in Ladner, well there are simply too many ifs...

If I should find myself working, the roof of our Hangar might be our refuge, if the remedial earthquake engineering successfully allows the building to withstand a tsunami(again too many ifs).

My adult daughter is on high ground, but is where she is, earthquake proof? Not so sure about that.

My young adult son could be anywhere on the lower mainland contracting. Today my younger daughters are at school while My wife works in Richmond. Her refuge would be the roof of the hospital or she could be in transit, and caught in a massive traffic jam, my point being the re are too may WHAT IFS.

The images out of Japan are mind blowing, (the catamaran perched on the roof of a two story building...)

Until one sees the effects of 8.9 and a resulting wave, how could one engineer adequate protection from the staggering VOLUME of water displaced by the shifting sea floor?

[better4me]

Don,

You might be interested in a 2005 U of Simon Fraser study on Tsunami probability in the Fraser River Delta.

City of Richmond has a website page discussing this study:

http://www.richmond.ca/safety/prepare/city/hazards/tsunamis/Tsunami_Study.htm

Short Form Conclusion:

Professors John Clague (Department of Earth Sciences, Simon Fraser University) and Ian Hutchinson (Department of Geography, SFU) completed a study of near-surface sediments beneath the plain of the Fraser delta in the summer of 2005. Their objective was to determine whether or not any prehistoric tsunamis had crossed what are now Richmond and Delta. A total of 33 cores were retrieved from sites where the likelihood of tsunami deposit preservation was highest. The cores likely preserve sediments dating as far back as 4000 years ago. The investigation revealed no evidence of tsunami deposits in the Fraser River delta. Drs. Clague and Hutchinson could not completely rule out the possibility that tsunamis have inundated portions of the Fraser River delta in the past, but but that the tsunami threat to Richmond and Delta is very small.

[Trader]

I'm sure everyone has seen tons of video. This was shot by someone on the street and show on Japanese television--left me absolutely speechless as you see it start from a trickle. Good luck EVER building for this contingency!

[Chipndeal]

I'm sure everyone has seen tons of video. This was shot by someone on the street and show on Japanese television--left me absolutely speechless as you see it start from a trickle. Good luck EVER building for this contingency!

The video is 6 minutes long and only near the end you see the water flow slowing. It keeps coming and coming for six minutes. My heart goes out to them.

I realise that the top half of Honshu island is not as densely populated as the bottom half but Sendai appears to have over 1 million people. Despite having the strongest earthquake and a tsunami of biblical proportion, the death toll which could be about 10,000 or so is remarkably low. It shows how prepared people are.

Next time the fire alarm goes off in a building, people should consider evacuating instead of thinking that nothing will happen to them.

[Don Hudson]

better4me, thanks very much for finding/providing the link to the SFU study. I think the information is very helpful in assessing risk and making practical decisions on what how to protect oneself. City governments have made plans based upon the more broadly-accepted scenario of a tsunami on the west coast of Vancouver Island, which is reasonable. I thought I would "look the other way where many weren't looking" to see what had been examined, if anything. - Good link! In fact there is a huge amount of information on the web that deals with these questions and many others, for the Pacific Northwest. The study to which you've provided the link also mentioned underwater landslides on the Fraser River Delta, creating "local" tsunamis (mainly west-bound, towards Galiano) and that's something I had never imagined but it makes sense. The article observes that the delta would absorb much of the energy from an 18m wave at Galiano and Mayne, but only 2m at Tsawwassen. From the article:

Collapse of the Front of the Fraser River DeltaA strong local earthquake could conceivable cause a landslide at the front of the Fraser River delta, where it slopes into deep waters of the Strait of Georgia. The landslide, if large and sudden enough, might generate a tsunami. The unconsolidated sediments forming the delta front may also fail without a seismic trigger, and yet still produce a tsunami.

Landslide-induced tsunamis are particularly dangerous because the waves may locally be very large and the warning time very short. For example, in November 1994 a submarine slide in Taiya Inlet created a wave that reached a height of nine to eleven metres at the shoreline in Skagway, Alaska, causing one fatality and over $20 million of damage.

It has long been recognized that the western front of the Fraser delta is at risk from submarine landslides. The Fraser River discharges about 17 million tons of sediment into the Strait of Georgia each year, and much of this sediment accumulates on the steep frontal slope of the delta. Small slides are common in this unconsolidated material, but are shallow-seated and moved down the delta front over a period of hours and consequently did not produce tsunami waves.

Researchers have investigated two potential modes of failure at the southwestern delta front. They conclude that a large slide could generate tsunami waves up to 18 m high on the east shores of Galiano and Mayne Island, but that the tidal flats of the delta foreshore would reduce wave energy, and waves at the shoreline in Tsawwassen would likely not exceed two metres, even if they coincided with high tide.

Trader;

Good luck EVER building for this contingency!

Indeed!

Those are political decisions as much as scientific and engineering decisions because many people here and in the US, (thanks to Bush) view science the way they view politics...as a "maleable enterprise where outcomes alter depending upon the power to persuade and convince" - it isn't possible to "sell" a case entirely based upon science. That's how the notion of "lobbying" came into common use of course.

However, the actual engineering calculations would be straightforward as very little is not known, mapped and understood in terms of the anticipated forces of such a wave and the underlying, supporting geological structure (upon which walls, berms, etc would be built), in the low-lying areas to be protected.

The study has clearly been done by the SFU profs, which would be part of any decision to actually spend the money vice spending it somewhere else of "higher" priority.

That's where power politics comes in, and sometimes it even works out better. Not often though, bringing to mind Richard Feynman's quote above, which all politicians and managers in high risk industries ought to be required to memorize as part of their degree, - or MBA...

I think most of us, those on the west coast anyway, know the mechanism behind the violence of a subduction earthquake and resulting tsunami but this link provides a pretty graphic, home-workshop illustration of the process.

Don

Edited to provide link to youtube video

[Guest]

These towns existed for centuries but ........  Drone Footage: http://www.bbc.com/news/world-europe-37182784

Italy earthquake: Death toll passes 240 as rescue efforts continue

The death toll in the Italian earthquake stands at 241 as rescuers continue efforts to find survivors.

Dozens of people are believed trapped in ruined Amatrice, Accumoli and Pescara del Tronto, in mountainous central Italy.

There have been hundreds of aftershocks since the quake struck, hampering relief efforts and damaging already unstable buildings.

More than 4,300 rescuers are using heavy machinery and their bare hands.

Rescuers have advised journalists and bystanders to leave Amatrice urgently, as "the town is crumbling", the BBC's Jenny Hill says.

Another powerful aftershock struck the town on Thursday afternoon, sending a huge dust cloud into the air.

• Follow the latest developments here
• Rescuers ask locals to unlock their wi-fi
• Read the survivors' stories
• Aerial shots of quake-hit Italy
• In pictures: before and after
• Grief and anger in Italian press

Many of the earthquake's victims were children, the health minister said, and there were warnings the toll could rise further.

The heaviest death toll was in Amatrice - 184, officials said. Another 46 died in Arquata, and 11 in Accumoli. A further 264 people have been treated in hospital.

Officials revised down the number of dead after earlier giving a figure of 247.

Media captionDrone shows destruction in Pescara del Tronto

The 6.2-magnitude quake hit at 03:36 (01:36 GMT) on Wednesday 100km (65 miles) north-east of Rome.

"We are sleeping in the car and there were shocks all night. When the biggest one came, the car started moving and shaking," said Monica, a survivor from Amatrice.

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At the scene: BBC's Damian Grammaticas in Pescara del Tronto

Two firemen burrowed deep into the rubble looking for a survivor. "It's a dog," one of them shouted out.

For half an hour the men kept digging. They passed water down to be given to the animal. And eventually they worked it free, then emerged, carrying it to the surface. There was a ripple of congratulations through the crowd.

"It doesn't matter to us if it's a person or an animal, we save it," said Gianni Macerata, the fire officer in charge.

So the digging goes on. But so little is left of Pescara del Tronto it is unlikely that more survivors will be found here.

It seems unlikely too that this ancient little place, that has stood for centuries, can ever be rebuilt. Hundreds of years of history ended in an instant.

Read more from Damian

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A tented camp has been set up, as so many buildings are now unsafe.

Prime Minister Matteo Renzi was chairing an emergency cabinet meeting on Thursday. The agenda included reconstruction plans for the devastated area.

Media captionEngineer and rescuer David Fabi says it is now a race against time Image copyright AP Image caption Amatrice: Most of the pretty, historic town is now rubble, blanketed in grey dust Image copyright Reuters Image caption The interior of a home in Amatrice exposed by the quake

Rescuers said they had pulled five bodies from the ruins of the Hotel Roma in Amatrice. As many as 70 tourists were staying at the hotel when the quake struck. Many are feared to be in the rubble, though several were pulled out and given medical care.

Many of those affected were Italians on holiday in the region. Some were in Amatrice for a festival to celebrate a famous local speciality - amatriciana bacon and tomato sauce.

Late on Wednesday there were cheers in the village of Pescara del Tronto when a young girl was pulled alive from the rubble after being trapped for 17 hours. Almost all the houses there had collapsed, the mayor said.

Media captionSister Marianna: "I went outside to ask for help, but no one heard me"

Among the victims was an 18-month-old toddler, Marisol Piermarini, whose mother Martina Turco survived the deadly 2009 earthquake in L'Aquila and moved away from there after the experience, Italian news agency Ansa reported.

Ms Turco was being treated in hospital after being pulled from the rubble in the village of Arquata del Tronto, Ansa said.

Image copyright Reuters Image caption Amatrice residents spent the night outdoors

The mayor of Amatrice said three-quarters of the town had been destroyed and no building was safe for habitation.

The country is no stranger to earthquakes: the 2009 L'Aquila tremor killed more than 300 people and in May 2012 two tremors nine days apart killed more than 20 people in the northern Emilia Romagna region.

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Why is Italy at risk of earthquakes? By Jonathan Amos

Earthquakes are an ever-present danger for those who live along the Apennine mountain range in Italy.

Through the centuries thousands have died as a result of tremors equal to, or not much bigger than, the event that struck in the early hours of Wednesday. The modern response, thankfully, has been more robust building and better preparation.

Mediterranean seismicity is driven by the great collision between the African and Eurasian tectonic plates; but when it comes down to the specifics of this latest quake, the details are far more complicated.

The Tyrrhenian Basin, or Sea, which lies to the west of Italy, between the mainland and Sardinia/Corsica, is slowly opening up.

Scientists say this is contributing to extension, or "pull-apart", along the Apennines. This stress is compounded by movement in the east, in the Adriatic.

The result is a major fault system that runs the length of the mountain range with a series of smaller faults that fan off to the sides. The foundations of cities like Perugia and L'Aquila stand on top of it all.

Quakes 'ever present' for Italy's Apennines

Image copyright Google/AP Image caption These pictures show the main street in Amatrice before and after the quake Image copyright Google/EPA Image caption These images show the hamlet of Pescara del Tronto before and after

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http://www.bbc.com/news/world-europe-37181933