Friday, June 16, 2023

Toronto's big earthquake fault - The Hamilton Fault

 All lively cities live under an earthquake threat.  There is something about the possibility of massive destruction that juices up things.  Are earthquakes more of a concern than imaginary carbon warming?  Maybe.

My main hypothesis is that you need water infiltration to have earthquakes in the continent interior.  That's probably true even for plate-edge earthquakes.

We have linears along the lake edge, and the west end of Lake Ontario is rising slowly, due to the isostatic uplift of the outlet, over by Kingston.  We did a lot of seismic reflection work, which is now hiding in the academic libraries.  Nobody wants to make the effort to get it.  Sad.

We have a huge fault under Hamilton that exhibits all the characteristics of a fault that goes every thousand years or so.  We did massive seismic scanning of the lake bed, and found it to be very disturbed by seismic motion.  This is an active fault, fed by water.  We are talking about an M7, albeit at remote odds, beyond the living memory odds of 1 in 100.  There are many other faults, all outlined by minor seismic activity.

Who cares?  If it is out of living memory, then people assume there is no chance of earthquakes.  However, all the destructive earthquakes are at the 1 in 1000 odds, rather than 1 in 100.  If the earthquakes are really frequent, then people build accordingly.  They suffer when the rare earthquake hits.

That is why I say that all cities of the world are at risk for the 1 in 1000 earthquake.  Early warning systems only work for trivial earthquake ground motion.  I have written scenarios for an M7 earthquake here, and it is not pretty.  Nor is it accounted for in any emergency scenario.  That is why Toronto is so lively, compared to a totally safe city, like London, Ontario -- blah.

ps. OMG, my brain is too active.  I suffer from my definition of the Brilliantitis gene, which was given to us by the Vikings.  It is the ability to burn the brain candle at both ends, but at 40 you better be a lush, or you'll kill yourself.  All the great people of the world have this -- Putin, Musk, etc.  For strongmen, they spend the brilliant part killing everybody in their way, and the depressive part killing more people to defend themselves.  Think Hilter, etc.  I have to hit my brain with a stick about this time of day, so I can sleep.  

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