212 replies to this topic

[VicHockeyFan]

When the Cascadia subduction zone rips it will be an earthquake several hundred kilometers long, it is not like the small localized single point earthquake.

The Cascadia megathrust earthquake of 1700 extended for 1000 kilometers.

Anchorage was located 120 kilometers from the Good Friday earthquake of 1964 and very severely damaged.

Santiago had significant damage in 2010 from an earthquake 250 kilometers away.

The 1960 Valdivia earthquake effected 400,000 square kilometers of Chile, 130,000 square kilometers severely which is an area four times the size of Vancouver Island.

**The 2011 Japanese earthquake severely effected an area about twice the size of Vancouver Island.

Scientists are only beginning to understand the Cascadia subduction zone and each year the understanding indicates it is more significant than previously thought.

The last Cascadia earthquake was in the top ten of all earthquakes in the last 500 years. potentially in the top three.

But I'm still not convinced that a person in one point on this fault is all that vulnerable. Yes, some point along this fault is going to get it, but what chance do WE have, or a person in Queen Charlottes? **You can put hundreds of Vancouver Islands into the fault line from Mexico up the coast to Alaska.

And that Cascadia quake of 1700, well a 1000km is nothing. You could take the severely affected area of that quake, even if it was 1000kmx1000km and place lots of those over the fault line. But I dobt that quake have severe impacts 1000km out each way. So say it was sever 500km out. You can place lots of 500kmx500km blots over Mexico to Alaska.

[pherthyl]

I bought some more ammo today......smarter than water.

I assume so you can shoot yourself before dying of thirst.

[pherthyl]

At the very least I think we should all have an earthquake kit in our cars. I mean even if the vehicle is damaged by falling debris there's still a good chance you'll be able to recover some contents of an emergency kit. Another location to store supplies, if you can afford it, is in a single-storey storage space. These rent for about $60-$100 month and at worst you'll have to ram your vehicle through security fencing to get into the compound.

Another place is work. Given how much time we spend there, it's pretty likely that it will happen when you're not at home. I don't have a separate kit here yet, but at least I have a nice solid 1950s steel desk to hide under. Single storey wood frame building so I think I won't be crushed.

[VicHockeyFan]

As for your probability of a big one... Where'd you get one in 10,000 or 50,000?
Everything I've heard is that big ones happen once every 300-600 years. The last one was 300 years ago. So let's say it is very likely to happen within 400 years from now. Typical lifetime of 80, I'm gonna say the chance is something like one in 5 for the lifelong Victoria resident.

See, that's where people don't understand statistics. I agree the big one is coming. But it ain't a 1 in 300 year chance of it being centred in Victoria. It's a 1 in 300 chance of it hitting on this fault, that is thousands of km long.

[Mike K.]

The fact Vancouver Island is an island -- breaking away from mainland North America -- suggests we're in a significantly more vulnerable tectonic zone than, say, Prince Rupert.

[VicHockeyFan]

The fact Vancouver Island is an island -- breaking away from mainland North America -- suggests we're in a significantly more vulnerable tectonic zone than, say, Prince Rupert.

You know an island is just part of the mainland, with a bit of a deep crack that got filled up with water, between us and the mainland, right?

But seriously, the fact we are on an Island ha s bit to do with things, but not that much. What part of the plate or whatever we are on makes the difference.

I think even after the big one, things might surprisingly go on as normal. A disruption of CASH supplies might pose a problem for commerce more than you'd know. How much loose cash do you have on hand, if we have no power for 14 days, to work bank machines and POS systems? I mean, a store can and will open, they have perishables to sell, they will do it with calculators and flashlights, but if nobody has cash?

That wasn't a huge issue 30 years ago.

[Mike K.]

You know an island is just part of the mainland, with a bit of a deep crack that got filled up with water, between us and the mainland, right?

And that big crack is a result of tectonic activity. We're living on a land mass that has and is continuously moving away from the mainland. Same idea as the San Andreas fault and the Baja Peninsula in Mexico -- over time California will rip away from North America.

[pherthyl]

See, that's where people don't understand statistics. I agree the big one is coming. But it ain't a 1 in 300 year chance of it being centred in Victoria. It's a 1 in 300 chance of it hitting on this fault, that is thousands of km long.

So you went from 1 in 10,000-100,000 in our lifetimes to 1 in 300 per year? Make up your mind.

1/300 per year is 25% chance for the average person's lifetime.

It's already been mentioned that a megathrust earthquake on the fault is not a localized phenomenon. The last one was 1000km long, and that stretch was near Victoria.

[jklymak]

And that big crack is a result of tectonic activity. We're living on a land mass that has and is continuously moving away from the mainland. Same idea as the San Andreas fault and the Baja Peninsula in Mexico -- over time California will rip away from North America.

I think you have that just about all backwards. Its probably better to not get plate tectonics lectures from watching Superman.

The Juan de Fuca plate is subducting beneath us, pushing VI towards the mainland. The island and the coast range are the result of of the crust being crumpled by the plate pushing against us laterally; think pushing on one end of a napkin.

http://www.pgc.nrcan.../manuscript.pdf

So far as I can tell, the models from NRCAN have us (Victoria) with a 21% chance of a catastrophic earthquake in the next 50 years, with an upper bound of 61%. So 1/5 is quite a bit higher than 1/10000. VHF should discuss the appropriate use of statistics with the geologists at Pacific Geological Centre.

ftp://ftp.seismo.nrcan.gc.ca/pub/hazardpubs/13WCEEp1065Onur_Seemann.pdf

[sebberry]

So far as I can tell, the models from NRCAN have us (Victoria) with a 21% chance of a catastrophic earthquake in the next 50 years, with an upper bound of 61%.

That's it, I'm moving.

[VicHockeyFan]

So you went from 1 in 10,000-100,000 in our lifetimes to 1 in 300 per year? Make up your mind.

1/300 per year is 25% chance for the average person's lifetime.

It's already been mentioned that a megathrust earthquake on the fault is not a localized phenomenon. The last one was 1000km long, and that stretch was near Victoria.

No, I meant 1 in every 300 years somewhere a big one hits, but it doesn't not hit the entire area Mexico to Alaska.

[pherthyl]

No, I meant 1 in every 300 years somewhere a big one hits, but it doesn't not hit the entire area Mexico to Alaska.

See jklymak's post. I think I'm going to side with the people that actually study this stuff.

[LJ]

Standard rule of survival taught to me when I lived in the UK is the rule of 3.

3 minutes without oxygen
3 days without water
30 days without food

Pretty basic stuff but makes a lot of sense.

So in our case if we have a major earthquake and our water system is damaged, you better be prepared to have access to clean water within 2 days if you want to stand a chance.

Its interesting to see new home construction with instant hot water on demand systems. They have no water tanks....yet in the UK and other parts of EU lots of homes and terraced houses etc have 200-500 gallon cisterns in their attic space, it was a very common practise after WW2 as it not only alleviated the need for drinking water it also maintained a regular pressure flow even in peak demand times.

Not sure I would want a 500 gallon cistern above my head in an earthquake.

[rjag]

Not sure I would want a 500 gallon cistern above my head in an earthquake.

As opposed to a 5,000lb brick chimney??? I look around at all the houses with brick chimney's and wonder how many people have gone into their attic to see what is on the floor around the chimney. Probably insultaion and floor joists and then a plaster or board ceiling....thats not going to hold the falling bricks. Need to put some strips of 1/2" plywood on the floor around it. I say strips as its kind of hard to put a sheet of 4x8 in an attic through a typical 18" opening.

[kenjh]

survived one more night ..sunshine and fresh air ...it's a great day ..enjoy!!!

[Bernard]

The Csacadia fault extends from Northern California to Northern Vancouver Island, it is not Mexico to Alaska. About 25-30% of the length of the fault is off of Vancouver Island.

A megathrust earthquake is not a single point on the fault, it is an earthquake that is hundred of kilometers long. The 1700 earthquake was not one spot, but a 1000 kilometer long one.

The scale of the energy released by the eventual Cascadia earthquake will be on the same as the energy released by every earthquake world wide for the last 100 years smaller than M7.5

When the Cascadia earthquake happens it will have significant impacts on Victoria.

We are under threat of a small damaging single point earthquake here in Victoria (Something M7.5 or smaller) but I know of no good predictions on the odds of that happening.

[kenjh]

tired of waiting for the big one ..I'm gonna go out motorcycle riding ..then diving ..let me know if I miss anything ...

[cluseau]

I spent a weekend a few weeks ago with a friend of the family from the US who is a physicist working in the field of earthquake prediction. He does NOT work in the statistical probability field; rather he has come up (with some other scientists) with a method for predicting earthquakes within a 2 week window using magnetic field measurements taken by satellites.

He has had a hard time publishing work because there is nobody that can peer-review their work (nobody else is working in the field). So they are publishing a book next year. No he's not a quack- has a day job with the US government using his skills and consults for the Chinese government. The Chinese seem to be the only ones who are building a system that can be used for these short term assessments.

They have to do research (request time) to gather data to do single point in time assessments of a particular region, as there is no active monitoring in place for this right now, and have successfully tested their methodologies. They successfully predicted the Sichuan earthquake in China in 2008 (killed 75,000 people) a week before it happened but they were only performing research so couldn't really do much with the data.

The idea they have is that if nations could monitor magnetic fields (much the way we monitor and predict the weather) we could have daily earthquake assessments on our cell phone home screen. What's missing is the government desire to do it- although if the Chinese do it then so too might the US and others (you know that old mine is bigger than yours thing)...

Anyway they do work WITH the statistical probability guys to see how things measure up. And currently the Puget region of the Cascadia subduction zone is the highest risk of an earthquake anywhere in North America, and has a 75% probability of an 8.0 or higher quake - which can cause a Tsunami - happening within the next 10 years.

Maybe Kelowna doesn't look so bad as a place to live after all...

[sebberry]

Maybe Kelowna doesn't look so bad as a place to live after all...

No kidding...

Let's hope he gives us a few days notice.

[G-Man]

I don't know, have you been to Kelowna? A few weeks drinking out of the toilet cant be that bad.