Big quakes no more likely than in past: study

Wanna see a thread flop? Haha, watch this. Not enough doom in this one!

Massive earthquakes are no more likely today than they were a century ago, despite an apparent rise of the devastating temblors in recent years, US researchers said on Monday.

The deadly 9.0 earthquake this year in Japan, an 8.8 quake in Chile last year and the 2004 Sumatra-Andaman earthquake that registered 9.0 on the moment magnitude scale have raised alarm in some science and media circles that such events may be linked.

But researchers at the University of California went back over the world’s earthquake records dating back to 1900 and found over time there was no statistically significant rise in the number of big quakes 7.0 and higher.

www.rawstory.com... tory+%28The+Raw+Story%29

This study would also corroborate the great work that ATS member PuterMan has done to show that statistically, The earth is not getting more quakes than it used to. It just appears to go through cycles of increased activity, then diminished activity.

Posted to drill some sanity back into this mess and do our thing: deny ignorance. But more specifically, to deny rumors circulating that the earth's seismicity is increasing.

Sorry to be the bearer of no doom.

yea,... its typical to have quake swarms in the midwest... they happen all the time,... same thing with those 9.0 earthquakes, they happen every few months. esp those quakes on the East coast like the DC quake... they happen as often as the CA quakes.



its increasing... all over. If you want to believe what they tell you then go to a CNN Forum

Just like the climate


Goes up and down depending on what period of time it is.

Earth is like a women with many hot flashes within her billions of year life cycle.


this lyrics help understand the earth and her "mood swings"

Cause your hot then your cold ,

you're yes the you're no

you're in then you're out

you're up and you're down

you're wrong when its right

its black and its white

katy perry

We've known this for a long while now. With the increase in numbers of seismograph stations and the increase in media attention, we get the illusion of a drastic incline in the numbers of earthquakes, while conclusive evidence has shown earthquakes have remained pretty steady within the past hundred years or so.

I don't doubt Puterman for one minute ...he really looks into it , however, given our minute time on this planet and being able to monitor it all (all the more now with internet access) can we Reeeeaaly say up or down or static ?

We have anecdotal evidence of 'biggies' but those folks couldn't put a whole years' worth together , or for that matter a decade or century...

Just saying...

I like the energy release graphs though , they seem to hold water , even though I have to say again , a blip on our landscape of existence.

Originally posted by TrueAmerican
It just appears to go through cycles of increased activity, then diminished activity.

If we are on the upside of increased activity, then wouldn't that technically mean earthquakes are increasing?

If they only went back to 1900, then how do we know the cycle does not increase activity far more, say every 300 years?

We know from the earths landscape that there has been some very extreme sudden earth movements. Could they be cyclic, thousands, if not millions of years apart?

Does this study really rule out peoples fears?

I don't know too much about this, but are very interested as I live in earthquake territory.

reply to post by ANOK


@TA, thanks for the plug. I am pleased to be vindicated in this.

If we are on the upside of increased activity, then wouldn't that technically mean earthquakes are increasing?

Yes indeed, if you count globally, they are but there are some things to take into consideration.

First Japan was a rarity. No one expected it and there is not a huge amount of historical evidence for it - but there is some. (I covered this here) The problem is that it could have been brewing for 1000 years and we would not see that. If you remove Japan from the equation since it's norm was 3 or 4 Mag six and the occasional mag 7 in recent times, then the rest of the world has actually decreased. Of the ~184 Mag 6 quakes and ~19 Mag 7, 70+ Mag 6 have occurred in the Honshu area, and 5 of the Mag 7s

Removing these from the figures to see what happened in the rest of the world we get 19-4 (say) = 15 Mag 7 (22 last year) and 184-67 = 117 Mag 6 (~154 last year)

It is quite clear that aside from Japan things have been quieter.

Second, it is my firm belief that the 'increase' peaked with Japan and we are going down the down slope. This does not mean no large earthquakes, and I expect one ~8.5 magnitude sometime next year - probably towards the end. IF I am right then the next 20 or so years will be akin to the 1970s and 80s when things were much quieter, which is another reason why the doomers like to pick that period as the starting point.

If they only went back to 1900, then how do we know the cycle does not increase activity far more, say every 300 years?

Because actually we do have reasonably useful figures going much further back and the ~55 year pattern seems to hold good. I am still researching this however.

We know from the earths landscape that there has been some very extreme sudden earth movements. Could they be cyclic, thousands, if not millions of years apart?

Yes indeed they could, but we cannot know that. We can go back several thousand years for the big quakes using geological evidence, but beyond that is not possible.

Does this study really rule out peoples fears?

Nothing rules out peoples fears when they are unfounded through a lack of personal research and fed by doom merchants and scaremongers often for profit. I am afraid that is the way it is. If you you do personal research you will slowly begin to see the picture.

This is known as the gambler's fallacy. For example, when flipping a coin, one hundred heads in a row does not increase the odds of throwing tails on the next one, it is still fifty fifty.

Earthquakes are a geological phenomenon. On the geologic scale, one hundred years of records is not even one flip of a coin. Claiming this indicates anything at all either way is actually nonsense.

Not so fast,TA.
They forgot to include global warming in the equation.
Ever heard of post-glacial rebound?
I know I didn't until I read an article about the land mass of Greenland rising due to the melting of the icesheets and glaciers.

The ice is melting so fast in Greenland that the giant island is rising noticeably as the weight is lifted. In some spots, the land is rising 1 inch per year. A vast ice cap covers much of Greenland, in some places up to 1.2 miles (2 km) thick. The ice, in place for eons, presses down the land, making the elevation at any given point lower than it would be sans ice. Scientists have documented on Greenland and elsewhere that when longstanding ice melts away, the land rebounds. Even the European Alps are rising as glaciers melt. Now, scientists at the University of Miami say Greenland's ice is melting so quickly that the land underneath is rising at an accelerated pace.

www.livescience.com...

According to the theory of plate tectonics, plate-plate interaction results in earthquakes near plate boundaries. However, large earthquakes are found in intraplate environment like eastern Canada (up to M7) and northern Europe (up to M5) which are far away from present-day plate boundaries. An important intraplate earthquake was the magnitude 8 New Madrid earthquake that occurred in mid-continental USA in the year 1811. Glacial loads have provided more than 30 MPa of vertical stress in northern Canada and more than 20 MPa in northern Europe during glacial maximum. This vertical stress is supported by the mantle and the flexure of the lithosphere. Since the mantle and the lithosphere continuously respond to the changing ice and water loads, the state of stress at any location continuously changes in time. The changes in the orientation of the state of stress is recorded in the postglacial faults in southeastern Canada.[18] When the postglacial faults formed at the end of deglaciation 9000 years ago, the horizontal principal stress orientation was almost perpendicular to the former ice margin, but today the orientation is in the northeast-southwest, along the direction of seafloor spreading at the Mid-Atlantic Ridge. This shows that the stress due to postglacial rebound had played an important role at deglacial time, but has gradually relaxed so that tectonic stress has become more dominant today. According to the Mohr–Coulomb theory of rock failure, large glacial loads generally suppress earthquakes, but rapid deglaciation promotes earthquakes. According to Wu & Hasagawa, the rebound stress that is available to trigger earthquakes today is of the order of 1 MPa.[19] This stress level is not large enough to rupture intact rocks but is large enough to reactivate pre-existing faults that are close to failure. Thus, both postglacial rebound and past tectonics play important roles in today's intraplate earthquakes in eastern Canada and southeast USA. Generally postglacial rebound stress could have triggered the intraplate earthquakes in eastern Canada and may have played some role in triggering earthquakes in eastern USA including the New Madrid earthquakes of 1811.[5] The situation in northern Europe today is complicated by the current tectonic activities nearby and by coastal loading and weakening.

en.wikipedia.org...

What are your thoughts on this?

reply to post by kdog1982


@PM: You're welcome.

kdog, that's a very interesting theory, but how are they going to prove the New Madrid quakes were caused by this rebound stress? Everything I've read is about the known fault there. And so they mention the land rebound, but are they documenting more quakes because of it than usual in Greenland?

But if so, maybe the Yellowstone quake of 1959 could have been same? And what about Alaska 1964? I dunno man. An awful lot of big quakes have happened on interplate faults- some might be due to it, but most are likely just faulting and stress releases from plate movements.

Originally posted by TrueAmerican
reply to post by kdog1982

 

@PM: You're welcome.

kdog, that's a very interesting theory, but how are they going to prove the New Madrid quakes were caused by this rebound stress? Everything I've read is about the known fault there. And so they mention the land rebound, but are they documenting more quakes because of it than usual in Greenland?

But if so, maybe the Yellowstone quake of 1959 could have been same? And what about Alaska 1964? I dunno man. An awful lot of big quakes have happened on interplate faults- some might be due to it, but most are likely just faulting and stress releases from plate movements.

There is no proving the theory till it happens,in hindsight.

Think of it this way.
Say you are squeezing a ball from the top and bottom as it is spinning.
The middle will bulge out more then if,say it wasn't spinning,or it wasn't being squeezed.
Then you start to release that pressure at the top and the ball starts to become distorted in a sense.

To understand how glacial isostatic adjustment affects Earth's rotation rate, we note that the movement of mass on and beneath the Earth's surface affects the moment of inertia of the Earth; by the conservation of angular momentum, the rotational motion must also change. This is illustrated by a rotating ice skater: as she extends her arms above her head, her moment of inertia decreases, and she spins faster. On the other hand, as she extends her arms horizontally, her moment of inertia increases and her spin slows.

Another thing I don't know is,within those interplate "faults",if you will,think of it as a piece of cardboard being squeeze,with it either rising or lowering in a weak spot,ever so slightly,then suddenly gives way and drops or rises,depending on the situation.

According to the Mohr–Coulomb theory of rock failure, large glacial loads generally suppress earthquakes, but rapid deglaciation promotes earthquakes. According to Wu & Hasagawa, the rebound stress that is available to trigger earthquakes today is of the order of 1 MPa.[19] This stress level is not large enough to rupture intact rocks but is large enough to reactivate pre-existing faults that are close to failure. Thus, both postglacial rebound and past tectonics play important roles in today's intraplate earthquakes in eastern Canada and southeast USA. Generally postglacial rebound stress could have triggered the intraplate earthquakes in eastern Canada and may have played some role in triggering earthquakes in eastern USA including the New Madrid earthquakes of 1811.[5] The situation in northern Europe today is complicated by the current tectonic activities nearby and by coastal loading and weakening.

en.wikipedia.org...

Originally posted by PuterMan
Second, it is my firm belief that the 'increase' peaked with Japan and we are going down the down slope.

I hope you are right. Thanx for the reply.

Whatever happens it's a waste of energy worrying about it I guess, not much we can do. It's just one of many ways to hasten our demise.

Originally posted by ANOK

Originally posted by PuterMan
Second, it is my firm belief that the 'increase' peaked with Japan and we are going down the down slope.

I hope you are right. Thanx for the reply.

Whatever happens it's a waste of energy worrying about it I guess, not much we can do. It's just one of many ways to hasten our demise.

My wife put it as,why are you spending so much time on there worrying about earthquakes,nothing you can do about it,so spend more time with me and your family.
I thought about it for a moment and responded,
well,your friend on facebook,who you have been chatting with all day is all in a tizzy about how her dog hasn't pooped today,nothing you can do about that either,can you.
Needless to say,
I slept on the couch that night.

To each his own.

reply to post by kdog1982


Lol yeah I hear ya.

I think I was just trying to reassure myself haha. Not that I'm scared or anything, I'm 6'6" 250lbs, and tough as nails.

Nice find TA.
I just stumbled upon the original journal article referenced in your OP link, and thought I would add it.
Global Risk of Big Earthquakes has Not Recently Increased
This links to the full PDF (only 5 pages).
Now we can see, in detail, what methods they used to reach their conclusion.

reply to post by Olivine


You know, I often have to do this myself for some stories. They write about it, but don't include the source. So thanks for going and digging it up. Rawstory lately has been showing itself to be the staunchly Democratic mouthpiece it always has been, but more so than usual. And the quality of their stories has dropped. They could have easily included the source.

As to the PDF you linked, it provided some interesting info, although it can be somewhat confusing.

The estimated global rate of very large (M >9) earthquakes is still very uncertain because only five such events have occurred since 1900. The recent elevated rate of large earthquakes has increased estimates of large earthquake danger: The empirical rate of such events is higher than before. However, there is no evidence that the rate of the underlying process has changed. In other words, there is no evidence that the risk has changed, but our estimates of the risk have changed.

So there is an elevated rate of large quakes, but not overall underlying seismicity? That is not very comforting- and besides, this study eliminated a couple of 8+ quakes completely as triggered events. So if another 9+ happens in the next few years, then what? At what point are there too many big quakes above "normal?"

Too bad we've only been scientifically monitoring quakes for some 100 years. Would be great if we could compare this era to say, 5000 years ago.