Sunday, January 24, 2016

Latest Toronto seismicity

Lest we forget.  Alaska just had an M7.1 that woke everybody up, but no damage.  That's the trouble with preparing for earthquakes in this neck of the woods -- those in power say we're no Alaska or California, blah, blah.  Problem is that a rare earthquake for them is an 8 or 9, for us it's a 6 or 7.

This is the latest seismicity map for Southern Ontario.  The two lines mirror the two zones in Oklahoma, and show the famous 'Enid Gap'.  These lines are the ancient Precambrian megathrusts, and are responsible for all the big seismicity in this area, including New Madrid.  We imaged them clearly in Canada, but nobody in the US has made the effort.

So OK, New Madrid, and Toronto have the same mechanism, but the difference is the rate. (Sounds like an old joke).  I'm just noting this, and I'm not going to engage in useless lip-flapping again.

** I have said before that Pickering has no hope with a 7.  I had hoped it would die soon, but will extended forever.  :(

ps.  the vw saga, the Niagara Tunnel to Nowhere, Oklahoma, all show how you can successfully avoid basic physics.  :)

pps.  At the very least, people in the GTA should secure their knick-knacks with seismic wax.  This just happened in Alaska.


Jenny said...

That's interesting. I have a friend in London, ON and she has never mentioned earthquakes. As for me, I live in the Twin Cities, MN, about as far as you can get from quake activities. I fascinated with quakes, but have never been in one, even with my many trips to California and other quake zones. Though I still have a detection device in my house just in case the big one hits New Madrid... and now I can worry about Southern Ontario too.

CB said...

I have a question,

The distribution of quakes along the lines you have laid out has some very densely populated areas, and some that extend for hundreds of kilometres with nothing. Is that caused by the distribution of sensing equipment, or the amount of time we have been collecting records, something else, or do quakes simply not occur in those regions? Over time, would the lines tend to fill in with quakes?


Another Guy from T.O.

Harold Asmis said...

The lines have quakes where they have water. These are natural seeps, in that the lakes are dripping down into the faults. In Oklahoma they are bringing water to the faults by injections.

CB said...

So through the sections of lake Erie say, where there are no measured quakes, is the rock there just not as permeable, or hasn't cracked and therefore there is no seepage?

Harold Asmis said...

In that section of Lake Erie there is a huge Precambrian basin that may screw everything up.