Tuesday, August 30, 2016
The earthquake that will destroy Toronto - Part 1
You can use this as your screen saver. :)
I once wrote 'The Great Toronto Earthquake'. A few days later everybody felt an earthquake from up North. I had 10,000 hits in a day. It was a glorious day, and one I hope to never repeat. If I am lucky, I won't see this upcoming big one. :)
Underneath Toronto, we have a fault that is every bit as good as New Madrid or Oklahoma or Italy. The only inconvenience is that it last let go a thousand years ago. No stories from the first people, since they were in endless war around here. No settlers, no nothing.
The only record is in the sediments of Lake Ontario. I've seen all the geophysics from the lake. Anybody else who has seen the records is dead. The records lie buried in landfill, or made into toilet paper by Harper. Or even worse, unindexed in huge digital files.
This is a monstrous fault, in the Precambrian. It has many twins, some of which go to New Madrid and Oklahoma. I call them our Megathrusts, because they formed during a mountain building period about a billion years ago. The Grand-daddy of them all, the Grenville Front is right under the proposed Bruce nuclear waste thing. A geologist associated with that project said, "No worries, it's off in the lake." But as my yellow arrow shows, the faults are shallow-dipping.
At the outcrop of these faults, the hanging wall is all broken. That is why you can plot straight sections of rock all the way down the line. On one side, the rock is solid (the footwall), on the other, there is no rock because it's all broken up. Our CN Tower was built on this rock, there was no continuous bedding across the site.
All our local seismicity is on this fault. They are 3's and 4's, and only the seismometers feel them.
-- to be continued.