Expect the Unexpected: More 9.0 Megaquakes Are Coming, Study Says

[bananas]

Source: NBC

No one should be surprised if a magnitude-9 megaquake erupts off America's West Coast — or anywhere else around the Pacific Ocean's "Ring of Fire," for that matter.

That's the upshot of a study in October's issue of the Bulletin of the Seismological Society of America: Researchers say that computer models of future seismic activity, plus a check of past activity going back thousand of years, suggest most of the Pacific's earthquake zones are capable of generating shocks at least as strong as magnitude 9 every 10,000 years on average.

Seismologists were surprised in 2004 when a magnitude-9.3 quake and tsunami devastated Sumatra and caused more than 200,000 deaths around the Pacific Rim. They were surprised again in 2011 by Japan's 9.0 quake and tsunami, which killed more 15,000 people and touched off a nuclear catastrophe that continues to this day.

In each case, experts didn't think the area where one geological plate is diving beneath another — known as a subduction zone — was capable of generating a quake that strong.

<snip>

In addition to coming up with the 10,000-year figure for the probability of 9.0 quakes, they estimated that quakes of at least magnitude 8.5 should be expected at least every 250 years, and 8.8 quakes should be expected every 500 years.

<snip>

Rong and her colleagues compared their figures with the sedimentary record for the Cascadia zone, and came up with estimates that were somewhat different for that area. They said that 9.0 quakes should be expected every 1,000 years for Cascadia, with 9.3 quakes over a 10,000-year period.

<snip>

Read more: http://www.nbcnews.com/science/environment/expect-unexpected-more-9-0-megaquakes-are-coming-study-says-n203936

---

Note that those probabilities are per subduction zone, and there are multiple subductions zones, so the total frequency is much higher.

[bananas]

1. 'Megathrust' Earthquakes along Pacific Ring of Fire Predicted by Scientists

http://www.ibtimes.co.uk/megathrust-earthquakes-along-pacific-ring-fire-predicted-by-scientists-1465577

'Megathrust' Earthquakes along Pacific Ring of Fire Predicted by Scientists
By Hannah Osborne
September 15, 2014 22:30 BST

<snip>

Rong told IBTimes UK that their findings indicate that "given a long enough waiting time", most subduction zones are capable of producing earthquakes of M9 or above: "The reason that we haven't seen such size earthquakes along some of the subduction zones is that our historical earthquake record is too short."

Discussing the risk of the Cascadia subduction zone, she added: "The concern is not based on the current quietness of the Cascadia subduction zone, but on the turbidite study of past earthquakes. The average occurrence time of M9 earthquakes along the Cascadia subduction zone is about 500 years based on the 10,000-year turbidite study, but the occurrence of such earthquakes did not follow a simple periodic model.

"During the 10,000-year history, the subduction zone had some long quiet times (without a M9 earthquake within ~ 1000 years), and some busy times (five M9 earthquakes within ~1500 years). It is hard to say when the next large earthquake will hit the subduction zone. Nevertheless, we should be prepared for it at any time."

Over the last 100 years, there have been five earthquakes that measured above M9, including the 2011 Tohoku earthquake that devastated parts of Japan.

<snip>

[bananas]

2. M 9.0+ possible for subduction zones along 'Ring of Fire,' suggests new study

http://www.eurekalert.org/pub_releases/2014-09/ssoa-m9p090514.php

M 9.0+ possible for subduction zones along 'Ring of Fire,' suggests new study

SAN FRANCISCO -- The magnitude of the 2011 Tohoku quake (M 9.0) caught many seismologists by surprise, prompting some to revisit the question of calculating the maximum magnitude earthquake possible for a particular fault. New research offers an alternate view that uses the concept of probable maximum magnitude events over a given period, providing the magnitude and the recurrence rate of extreme events in subduction zones for that period. Most circum Pacific subduction zones can produce earthquakes of magnitude greater than 9.0, suggests the study.

The idea of identifying the maximum magnitude for a fault isn't new, and its definition varies based on context. This study, published online by the Bulletin of the Seismological Society of America (BSSA), calculates the "probable maximum earthquake magnitude within a time period of interest," estimating the probable magnitude of subduction zone earthquakes for various time periods, including 250, 500 and 10,000 years.

"Various professionals use the same terminology – maximum magnitude – to mean different things. The most interesting question for us was what was going to be the biggest magnitude earthquake over a given period of time?" said co-author Yufang Rong, a seismologist at the Center for Property Risk Solutions of FM Global, a commercial and industrial property insurer. "Can we know the exact, absolute maximum magnitude? The answer is no, however, we developed a simple methodology to estimate the probable largest magnitude within a specific time frame."

The study's results indicated most of the subduction zones can generate M 8.5 or greater over a 250-return period; M 8.8 or greater over 500 years; and M 9.0 or greater over 10,000 years.

<snip>

"Magnitude limits of subduction zone earthquakes" is co-authored by Rong, David Jackson of UCLA, Harold Magistrale of FM Global, and Chris Goldfinger of Oregon State University. The paper will be published online Sept. 16 by BSSA as well as in its October print edition.

###

Media contact: Nan Broadbent
Seismological Society of America
Phone: [phone]
E-Mail: [e-mail]

[Bosonic]

3. Global forecast of future earthquake activity produced by the Open Hazards Group

http://www.quakesim.org/

[mnhtnbb]

4. California is going to get a 'big one' one of these days. It won't be pretty.

Just MHO.

[jakeXT]

14. Most of California isn't in a subduction zone, volcanoes usually indicate one

Last edited Tue Sep 16, 2014, 04:16 PM - Edit history (1)

[roamer65]

17. The worst the San Andreas fault can produce is 7.5 to 8.

Highly doubtful CA will see a 9.0+ megaquake anywhere south of the Cascadia subduction zone off the coast of Northern CA. The San Andreas is a transform fault, which usually does not produce megaquakes.

Northward, the Cascadia subduction zone definitely has the potential for 9.0+ and that area is nowhere near as ready for an earthquake as CA.

[Kablooie]

5. I hate to disappoint but when a 9.0 hits I fully intend to be surprised.

[Enthusiast]

6. Plate tectonics is a hoax, just like global warming.

[GliderGuider]

7. Damn geologists, trying to scam us for more research grants!

They should just go work for the oil companies like they're supposed to! Leave the fear-mongering to the climate guys who have had so much more practice at it!

</sarcasm>

[Enthusiast]

8. Those geologists are getting rich I tells ya!

[Codeine]

9. Big Dirt. nt

[Stargazer09]

10. Cascadia

We are woefully unprepared for that one.

[catbyte]

11. The Cascadia Subduction Zone is the only corner of the Pacific Ring of

Fire that hasn't let loose yet. It might not happen for a hundred years, but if I lived in the Pacific Northwest, I'd make sure my earthquake insurance premiums were current. Of course, I tend to be a worry wart where natural disasters are concerned, so YMMV.

[uppityperson]

15. Yup. This is a good reminder I need to redo my car and garage kits before wonter

switch out food, water, supplies, make sure the spare clothes and boots are still good, etc. Nearing time to put the chainsaw and gas can back in the trunk also. My spouse jokes if I drove into a ditch somewhere, by the time they found me, I'd have the clearing done, log cabin built, garden in.

I hope to never have to use these kits.

[roamer65]

18. Good idea.

[valerief]

12. And more earthquakes s/b expecting around fracking zones. This is outside of the

historical events before the last 2 centuries.

[mountain grammy]

13. Mother nature will always be in charge and if she is pissed

we should be nervous.. I'm plenty scared

[blkmusclmachine]

16. ,

,