Thursday, September 1, 2016

The earthquake that will destroy Toronto - Rational Discussion

This is only for those who wish to be rational, as I am putting on my engineer cap, which I find is mostly boring.  I did this piece in the style of all those other ridiculous pieces, but it all had good science in it.  The most difficult thing is discussing odds or probabilities.  Even worse, there is an uncertainty band on those odds.  I put everything in PGV as the chance per year, as my best estimate

All the big disasters are a PGV over the seismic capacity of the general building stock, at about 1 in 500 per year.  That's because nobody builds for that.  Our building code goes for that level, but just to avoid total pancaking.  The interior fixtures are never covered, nor does does anybody care about functionality.

I have found that the 40 year old assumptions about sinusoidal motions have been creating horrible situations.  Chile gave us a hint of that, but it was ignored.  Earthquakes such as Italy don't teach us anything, because their Maffie concrete capacity is about 5 cm/s.

Toronto completely ignores earthquake risk, yet their odds of a disaster are the same as anywhere else because the preparation is non-existent.  Sure, California seismic hazard is higher in terms of PGV, but so is their capacity.  Earthquakes hit the ignorant pretty hard, and most cities are extremely ignorant.

I have a thing about weird condos, and crammed subdivisions.  The condos will crack at their internal boundaries, and the tract housing will be Dresden firestorms.  They always assume a rapid fire department response.  Nope.

The Pickering nuclear plant will release radioactive steam with this earthquake.  It might give everybody a chest x-ray, but that's about it.  Candu reactors have lots of internal water, lots of good concrete, and thermosyphoning.  Nevertheless, the reactors won't restart for weeks, and we'll have no gas and no electricity in the winter.  Perhaps there are consequences.  :)

ps.  the odds are a 6 or 7 every 500 years.  OK has shown us that 6's and 7's are practically bedmates.

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