Stephen Rees's blog

Thoughts about the relationships between transport and the urban area it serves

Posts Tagged ‘earthquakes

Will shaky soils kill the bridge?

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Massey-Bridge-rendering

I am not an engineer or a geologist. But I do know that soil liquefaction is a huge problem for structures in earthquake prone areas, like the one we live in. When the shaking starts what seemed to be solid ground is actually waterlogged sands and similar material – the result of millennia of silt being deposited by the Fraser River as it slows on its way to the sea – starts to move. The damage to buildings in San Francisco in its famous quake was due to similar soil conditions. They still cause issues there: a high rise called Millennium has piles that do not reach bedrock and it is both sinking and leaning.

When the Massey crossing was first contemplated it was these soil conditions that caused the engineers to reject the idea of a bridge and chose a tunnel instead. Those conditions have not changed since. The Geological Survey of Canada in 1995 reported that bedrock is around 1,970 to 2,300 feet below where the new bridge is proposed. More recently  B.C. Ministry of Transportation and Infrastructure had two holes bored to 1,099 feet “without tagging bedrock” – not really a surprise since there was another 1,000 feet to go.

We know that Greater Vancouver is going to experience a major earthquake since there has not been a major shift in the tectonic plates since European settlement started, but there was apparently a “big one” which was recorded as a tsunami that hit Japan. These events are hard to predict with any accuracy but many seismologists think it is “overdue”. No-one has ever built a cable stayed bridge of this size in these kind of conditions. Indeed it is very hard to think of why anyone would propose taking such a risk – anyone who has the imagination to envisage what happens to two massive towers unsecured to bedrock but linked by cables and a bridge deck when the soil beneath them liquefies and shakes.

“I think people tend to focus on the Big One. If you’re looking at the statistics there’s a one in 10 chance that it will happen within the next 50 years. I think of those as fairly high odds. If we had a lottery with that kind of probability you’d probably buy a ticket,” she said.

The “she” quoted is Earthquake Canada seismologist Alison Bird

Ask yourself, as Premier Christy Clark wants you to buy a bridge, do you feel lucky?

Written by Stephen Rees

December 1, 2016 at 11:25 am

The Dangers of Fracking

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And come to that the dangers of commenting on press articles on line. Recently I posted something using Disqus: it was in response to an article in a Squamish newspaper about the proposed LNG plant. Oddly, nothing in the article, or in the response to that time spoke to the source of the gas. That will come from an expansion of fracking – the practice of releasing hydrocarbons from “tight formations” which has been expanded very rapidly in North America in recent years. The process creates fractures in the oil and gas bearing rocks by injecting water and mix of chemicals under high pressure.

To be clear, I oppose any expansion of fossil fuel use. There is only one way that we are going to be able to slow down our current headlong rush to global catastrophe and that is to Leave It In The Ground. Most of the reserves of oil, gas and coil must not be extracted and burned. Fortunately, the alternative renewable resources are both economically and environmentally attractive – and are getting cheaper. There is much more employment potential in renewables too, so the previously perceived “choice” between the environment or the economy is now a false dichotomy.

Expansion of LNG export terminals in BC seems increasingly unlikely based on any realistic analysis of the finances but Christy Clark has yet to concede this, and is perfectly capable of continuing to increase the public subsidy of this folly. We are actually paying foreign corporations to exploit this resource, which would otherwise be unmarketable. So if the GHG use of fossil fuels is not persuasive enough, the record of fracking needs to be examined. There are two points I made – the first is that methane is released by fracking in a manner which makes it difficult to capture – or even measure. Since methane is a far more powerful greenhouse gas than CO2 that is cause for caution in itself. But there is also the effect of putting injecting water into the ground. Poisoning wells is the least of it (though the youtube videos of setting kitchen faucets alight seem entertaining). We live in a seismically unstable region. There will be a huge earthquake out underneath the ocean, probably south of Haida Gwai. (I wrote that last sentence on April 23 at 10:45. This morning there was an M6.2 in exactly that location but without a tsunami.) With huge a tsunami and lots of damage. But there is plenty of risk of on shore activity too: it will be smaller but also destructive in nature.

Now of course as soon as my post appeared the on line trolls leapt on it. At least some of them are going to be in the pay of the gas drillers or the proponents of LNG expansion. They are spending a fortune on PR efforts around pipeline and terminal expansion – and no contrary opinions must be allowed to go unchallenged. A Google search for “fracking in bc” turns up nearly a million hits.

I want to draw your attention to Oklahoma. There have been a lot of earthquakes recently in Oklahoma, and the spin doctors have been doing their best to deflect responsibility away from fracking. The state government seemed to have been persuaded. Up until now. The state is now admitting that fracking causes the earthquakes. There is also more coverage of the wider impact from the New York Times.

If you do not want to admit that global warming is a problem that is caused by burning fossil fuels, then I think you are unreachable by reason or argument. But then that process of proof by belief in a political doctrine appears to have taken hold with the Conservative faithful here as it has in the US. You can probably also cheerfully ignore the impact of poisoning the water supply: after all it is unlikely to affect us here and we have been seemingly unconcerned about the state of the water on reserves – especially those impacted by the tar sands. But the risk of increasing earthquakes ought to be something you take seriously here. Even though our present government seems to be quite content to leave schools in Vancouver vulnerable to the inevitable.

POSTSCRIPT Bloomberg is now forecasting that Half of U.S. Fracking Companies Will Be Dead or Sold This Year

Written by Stephen Rees

April 23, 2015 at 10:56 am

Rising sea levels, earthquakes to hit B.C., says study

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Richard Watts,  Vancouver Sun

Not a comfortable story for residents of the Fraser Delta to read. The conservative extimate of sea level rise from the IPCC is 90cm “by the century’s end” . But everything else I have been reading recently suggest things are going to start happening much faster than the IPCC predicted because they did not account for the “feedback loops” in the processes of global warning and climate change. For instance, as the polar ice caps have been melting, so less sunlight is reflected back into space and the dark surface of the ocean absorbs more heat than the bright surface of the ice. So that process can now be measured and shows the IPCC erred when it made its “conservative” estimate.

One major force is the melting of ice caps in the North and South poles and the world’s glaciers. This is coupled with an expansion in the volume of the oceans’ waters due to an increase in their temperatures brought on by global warming.

And that process can now be seen to be inundating low lying nations around the Pacific. Years – deacades –  before the IPCC thought they would be.

Meanwhile, in the Lower Mainland, the loading of sediment from the Fraser River is actually pushing the land surface downward, a process called subsidence.

Not only that, but the lack of dredging in the secondary channels of the Fraser (the Port only dredges the main shipping channel in the South Arm) means they are full of sediment. So there is less storage capacity for the spring freshet – the ice melt from the interior glaciers.

As also predicted, weather events have been getting more extreme, as global warming means there is more energy driving them. Climate change is not just wamer springs and longer dry spells – it is also more and worse storms.

So what we are looking at is a sesimically unstable area, that is sinking while sea levels rise – and the wetaher gets worse.  You might think that would be stimulating a lot of activity on the dykes – and a fresh examination of dredging policies, given the devasation that will occur when (not if) the dykes are overtopped. But so far all we have heard are platitudes and reassurances – not action. And my concern is that the message that this process has been speeding up is not being heeded by municipal, regional or provincial authorities.

Indeed, there is no sense of urgency at all in this story. Except for this little gem

“Once the big earthquake hits, within minutes the land all falls back down a metre or so and then the big tsunami hits, and it’s not going to be fun,”

Written by Stephen Rees

December 17, 2008 at 11:27 am