I had a discussion with a colleague today, about the likelihood of a major earthquake in California

[darkangel218]

What do you guys think? How likely is that Cali would experience an 8/9+ ( "the Big one&quot during our lifetime?

12 votes, 1 pass | Time left: Unlimited
	Very likely
	8 (67%)
	Remotely likely
	4 (33%)
	Not likely
	0 (0%)
	1 DU member did not wish to select any of the options provided.
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[Wilms]

1. Define "our" lifetime. n/t

Maybe then I'll pull an opinion out of thin air.

[darkangel218]

2. Well, lets say, within the next 40 years

[rjsquirrel]

5. The math cannot render that level of precision

In the scale of geologic time 40 years isn't even the blink of an eye. That various faults and the larger subduction zone are certain to shift and cause quakes can be pinpointed to within centuries in some cases, but even then it's probabilistic and depends on unknown or poorly understood variables that affect the cycles that can be observed in historical time or the geological record.

The question is thus asking for a gut feeling. No geologist will predict "the big one" with precision with any confidence on a 40 year interval. Could happen today. Could happen in 2060. From a geological perspective that's milliseconds apart.

[darkangel218]

8. Very true

[mnhtnbb]

9. Currently the USGS gives a 7% chance of an 8.0 or larger in CA in next 30 years.

Estimates of the chance of a magnitude 8.0 or greater earthquake hitting California in the next three decades have been raised from about 4.7% to 7%, the U.S. Geological Survey said Tuesday (March 10, 2015).


http://www.latimes.com/local/lanow/la-me-ln-chance-of-80-earthquake-in-california-rises-usgs-says-20150310-story.html


And a link to The Third California Earthquake Rupture Forecast


http://www.wgcep.org/UCERF3

[darkangel218]

11. Thank you ou for the links

So they pretty much doubles the "chances" of a major earthquake. Hmmm.. It doesn't look good.

[mnhtnbb]

16. I thought it was interesting they reduced the chances of the mid-level earthquakes

I'm glad I no longer live in California: earthquakes are just one reason among many.

[mnhtnbb]

3. I'm 64. I lived in Southern California from 1965-88.

I was a student at UCLA when the Sylmar quake hit in 1971. My roommate and I thought it
was the end of the world when we woke up at 6 am to the shaking...and shaking...and shaking.
Even at 6.7, that was not a "big one", although there were deaths and major collapse of
buildings at both Olive View Med Center and the VA in the SF Valley.

Yes, there was also the Northridge quake in 1994--also a 6.7. But I still think CA is overdue for a big one and it
very well could happen in the next 20 years (my expected lifetime).

[darkangel218]

7. I agree with you.

I think it's just a matter of time.

[Scuba]

4. Cali IS a major earthquake!

http://www.democraticunderground.com/1251616648

[darkangel218]

6. Hehehehehehe!!

That she is. looking forward to her coming back and *shaking* the ground a bit ( we are now outside of the SOP! Lol)

[SheilaT]

10. Where in California?

Which fault or fault system are you anticipating failing or moving, resulting in "the big one"?

I know that at various times over the years I've read predictions of earthquakes, always given in a percentage over time. Such as a 40% likelihood of a magnitude 6 within the next thirty years.

My understanding of earthquakes is that the kind of fault, exactly how it moves, and when the last time it moved significantly all come into play.

For those who are interested, John Nance wrote the best book I've ever read about earthquakes, titled On Shaky Ground. It came out in 1988. It devotes something like five chapters to the Good Friday Quake in Alaska in 1964. That was basically the event that confirmed the theory of plate tectonics, and Nance explains all that. He also writes about the New Madrid quakes of 1811/1812, and when I read that book, it was the first I'd ever heard of those quakes. The book is no longer in print, but is readily and inexpensively available on the internet. I cannot recommend it too highly.

[darkangel218]

12. Anywhere/everywhere.

Pretty much on the West Coast.
My colleague is from San Diego, moved here to FL and she was sighing with relief that she doesn't have to worry about shake ups.
I personally think northern California is higher at risk than the south . but that's just a gut feeling.

[SheilaT]

13. See answer 9 above.

Even if a magnitude 8 or greater does not strike within the next 40 years, she can be guaranteed that there will be other, smaller quakes over time. So she needs to make preparation for that near-certainty.

The only time I was in an earthquake, and aftershock of the Northridge quake, I managed to sleep through. Others in my travel group, staying in the same hotel, were awakened by it.

[mnhtnbb]

17. Apparently that report I linked indicates chances are higher in northern CA

than southern CA for a big one.

For 30 yr M≥6.7 probabilities, the most significant changes from UCERF2 are a threefold increase on the Calaveras fault and a threefold decrease on the San Jacinto fault.


http://bssa.geoscienceworld.org/content/early/2015/03/05/0120140093.abstract

[Yo_Mama]

14. Somewhere in between "Very" and "Remotely"

Earthquakes are triggered by a long slow series of small changes in the earth's crust, and the balance of our lifetimes is too short a time to make to make an accurate statement.

[Downwinder]

15. Not much time left in my lifetime.

[LastLiberal in PalmSprings]

18. I live 15 miles from the San Andreas fault.

We've already had two 7.1 quakes in the last decade, neither related to the San Andreas. Since we live in the desert there's not a lot of people or structures to be affected.

At least we don't have tornadoes, floods, hurricanes and all the other goodies that plague the coasts and Midwest.

Now, if we could only get rid of the meth labs...