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-   -   mega-thrust earthquake along cascadia fault (https://www.mersenneforum.org/showthread.php?t=13583)

science_man_88 2010-07-06 12:10

mega-thrust earthquake along cascadia fault
 
I was watching discovery talk about a megathrust equake that would supposedly happen soon (last one like it in 1700's) but the odds they give even now is 1/200,000 to happen in the first 14 months of the cycle they see, and 1/4000 to happen in the 2 week after-part even these odds put it over 4000 years in the future so why are they talking of it happening soon ?

cheesehead 2010-07-06 21:12

[quote=science_man_88;220676]even these odds put it over 4000 years in the future so why are they talking of it happening soon ?[/quote]No, those odds do _not_ "put it" any amount of time "in the future". That is not the way to interpret that number.

Are you thinking that because the earthquake has a (I'm not sure how to interpret your description, so here's a guess) 1/4000 chance of happening in the next year, that there must necessarily be 4000 years before it happens? That's not how it goes. All the 1/4000 figure means is that it's a simple way of conveying some persons' [U]prediction[/U] over a certain time period, not over 4000 years.

The Cascadia fault is not performing arithmetic. It doesn't care about the 1/4000 figure. It doesn't have to count up to 4000 before it slips again. It could slip tomorrow.

philmoore 2010-07-06 21:25

He may be referring to the Juan de Fuca fault off the coast of Oregon, Washington, and British Columbia. It slipped on January 26, 1700 with an estimate quake of Richter 9. Some geologists have suggested that it repeats every 300 to 500 years, but I have read one geologist's predicition that there is an 80% chance of it going in the next 50 years! I've been planning to get earthquake insurance on our home soon...

science_man_88 2010-07-06 23:53

[QUOTE=cheesehead;220698]No, those odds do _not_ "put it" any amount of time "in the future". That is not the way to interpret that number.

Are you thinking that because the earthquake has a (I'm not sure how to interpret your description, so here's a guess) 1/4000 chance of happening in the next year, that there must necessarily be 4000 years before it happens? That's not how it goes. All the 1/4000 figure means is that it's a simple way of conveying some persons' [U]prediction[/U] over a certain time period, not over 4000 years.

The Cascadia fault is not performing arithmetic. It doesn't care about the 1/4000 figure. It doesn't have to count up to 4000 before it slips again. It could slip tomorrow.[/QUOTE]

sorry not thinking and philmore I'm saying they say that about the whole cascadia fault not just the part you talked of.


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