[conspire] Did you guys feel the 4.2 earthquake today?

[Ron / BCLUG]

Steve Litt wrote on 2023-10-22 17:56:

> As time went on I got better at estimating how far a quake was from me.

As I read about all the quakes you've experience, it dawned on me that 
I've felt only a couple memorable ones - each quite minor.

That's in 30+ years of west coast living.


I do, however, wish we had them more frequently.

Seems the stress just keeps building up with no release of any significance.

And being in a subduction zone, do smaller quakes even work to release 
built-up energy? Seems like they should.


> Megathrust earthquake are the world's largest earthquakes. The last
> Cascadia earthquake is estimated at magnitude 9.

https://earthquakescanada.nrcan.gc.ca/info-gen/faq-en.php#mega_how_often


As frequent as 200 years apart over the last 6000 years.

Most recent major quake: 300 years ago. I know that "overdue" isn't an 
accurate term, but "Sword of Damocles" seems fitting.



Today I learned there's a maximum to the "amplitude" of the shaking that 
tops out around a 7 or 8:

> If the shaking of a magnitude 7 is 10 times greater than a magnitude 6 and 100 times greater than a magnitude 5, is the shaking from a magnitude 9 100 times greater than a magnitude 7
> 
> No. Earthquake shaking, in the frequencies that damage buildings, increases to a maximum between a magnitude 7 and 8 earthquake, then the shaking simply involves a bigger area. However, the duration of shaking for a megathrust earthquake is much longer. It can be several minutes. This long duration can result in damage to some types of buildings that might not be damaged at the same strength of shaking produced by a smaller earthquake.



I oughta check if I've got enough supplies for an emergency and put 
together some kind of kit.


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