Quakes trigger Quakes

Just realized you posted more on this....chewing on it now....

Originally posted by Valhall
It's referring to an amplitude that abruptly destroys the rock strength. This isn't a matter of INCREASING amplitude, but a specific amplitude that can destroy rock very efficiently.

In other words, the article speaks of the amplitude of incoming wave - not about what is around the rock (void or otherwise).

I agree with that. But that does not mean that drilling and mining don't nonetheless cause the concerns raised previously in my posts, right?

EDIT: And I agree that continued research in this area would be interesting...

[edit on 15-10-2005 by loam]

Originally posted by loam

I can't see why not?

I can see why not. They don't have anything to do with each other! Absolutely nothing. You can talk about a human action that might be able to invoke a seismic event. Or you can talk about the post-production state of the reservoir that might behave differently than before the reservoir was produced. BUT THEY DON'T HAVE A CONNECTION. I might add - that the activities that tend to take place in the life of the well that COULD cause a pseudo-seismic event come BEFORE the production typically.

What are the mechanics, then, of induced earthquake activity caused by drilling? Can it lead to compaction or not? If it does, why does that not reconcile with your own assertion that sound waves travel more freely in denser the material?

The only mechanics of drilling that could cause compaction of rock is extremely near the wellbore. And that compaction is most likely carried up the wellbore during the drilling operation. Anything left behind is a minute layer (and I'm talking inches NOT feet) about the wellbore wall. It's not doing anything in the grand scheme of things.

Which I assume you mean by either naturally occurring seismic activity or something man-made.

No - you have assumed wrong. My statement was about perforating, fracturing, pressure testing and seismic testing events associated with a well. That has nothing to do with naturally occuring seismic activity. That statement was about man's activity.

How did you get there? Are you saying this would not even lead to additional compaction?

I got there through sheer common sense. See comments above. You can't take a singular event that occurs BEFORE the post-production properties of the reservoir, and say that has anything to do with a theory that expounds different behavior of the rock AFTER the production of the well. They are two totally separated issues. Furthermore, I think the whole discussion is based on not understanding the original reading referenced. So what are you going to do about that?

But Valhall...There is PLENTY of evidence that compaction occurs frequently and on a significant scale. Remember this is a global discussion. You certainly don't maintain that deposits all over the world are substantially the same?

I read your link. It was concerning California, and I'm not convinced. I'm not saying I'm discarding it, I'm just saying that there are a LOT of geographic factors taking place in California...now isn't there? I wouldn't call this PLENTY. But I will read anything further you submit.

Pumping is also often used for extraction when the pressure is no longer sufficient.

Pumping what? Are you speaking of wellhead pumping to extract hydrocarbons from a well that no longer can flow to surface? If so, yes, you are correct. That has nothing to do with this conversation. I stated that at some point the well would not produce at a profitable rate that include having to put a popping-johnnie on it or whatever. At some point the well will be closed in and P&A'd. period.

But is still weaker than was true when the deposit was untapped.

You totally missed the point. The less the pore pressure the more dampening.

This has other concerns...

Yes it does. But you can either crap or get off the pot, now isn't that right? You don't wait to achieve perfection. You make step-wise improvements toward perfection. I can't help but notice that those who cry "foul" are the first ones to also be hesitant in the solutions submitted. Why is that? Do they need the situation to degrade further before they can make a decision? Or is it a reluctance to accept a dimunition of the gripe ability?

I'm not sure.

We are currently in a thread about a false threat based on a misinterpretation of research, and some one has offered up a solution to the factors you have brought up. Your response is to wave it off because of "other factors".

Cool! At least the original premise of the threat is not something that will kill us tomorrow, so I guess it is acceptable to wring our hands a bit longer on how to deal with GHG's. Meanwhile, we move on...blaming it on somebody else.

This isn't a matter of INCREASING amplitude, but a specific amplitude that can destroy rock very efficiently.

Yes, Val. I knew that. As I explained, the astounding thing about this study is that it determined amplitude is the critical factor in triggering new quakes, not frequency as was previously believed.

Originally posted by Valhall

We are currently in a thread about a false threat based on a misinterpretation of research, and some one has offered up a solution to the factors you have brought up. Your response is to wave it off because of "other factors".

The podcast put forward several ideas - and the research was not misinterpreted. You are focusing on only one of many questions (not statements) - concerning yourself exclusively with the oil industry - and presenting a legal argument that denies liability.

The echo chamber idea applies more to emptied aquifers and underground rivers, and maybe, gas reservoirs. ...Size, shape, and material are very relevant - so it would not be 100% applicable. Ie. some places would work one way, others another. In addition, liquid is a barrier that attenuates wave propagation - so removing the barrier certainly will have an impact.

...You seem to be interested exclusively in the oil industry - and concerned primarily with proving that oil extraction cannot impact the geological environment, or damage the planet's geology. I agree - no direct cause and effect relationship ever will be proved. It's a system.


I - and others - are interested in investigating the ecology - or interrelatedness - of this planet's geology, and the many different ways that industrial activities might have an impact. ...The general idea is that we have been messing with the earth - and now it's messing back, even geologically. ...We're just looking around.



.

Thanks soficrow. Actually, I'm not centred mainly on the oil industry. I thought I would give you a break by not busting your chops over the fact you came down on people who are emptying water aquifers with their personal drinking needs and farming irrigation needs.

Originally posted by Valhall
I've got one more example, and then I'm leaving this thread behind,

You also told me in an email that you wouldn't post in threads if you "didn't agree" with me.

But hey - you've convinced me. ATS according to Val does not accommodate the free exchange of information, ideas, or collaboration. Only postulates and hypothesis that support the corporate status quo are welcome. I will script my future podcasts and posts accordingly.



.

Valhall:

I sense you think I have some agenda here. I do not. The questions I'm asking are legitimate inquiries from you and were not intended rhetorically. I am not engaged in "a reluctance to accept a dimunition of the gripe ability?" I also do not claim I know anything for certain on this particular subject matter. However, I do claim an interest in the matter and nothing prevents me from asking questions or presenting material I find that contradicts statements made on this thread and seeing how they are substantively responded to.

Take a deep breath and let's keep this civil... I am prepared to admit when I am wrong and when I'm not sure about something. No additional interpretation need be applied to my posts. If I need to proclaim my take on any given political policy, I generally can do so quite explicitly.

In any event,

Originally posted by Valhall
I can see why not. They don't have anything to do with each other! Absolutely nothing. You can talk about a human action that might be able to invoke a seismic event. Or you can talk about the post-production state of the reservoir that might behave differently than before the reservoir was produced. BUT THEY DON'T HAVE A CONNECTION. I might add - that the activities that tend to take place in the life of the well that COULD cause a pseudo-seismic event come BEFORE the production typically.

OK, if the post production state is "caused" by man (drilling, mining & pumping), and that leads potentially to more impactful seismic events, isn't that the point of this thread? Shouldn't we more fully understand that?

The only mechanics of drilling that could cause compaction of rock is extremely near the wellbore. And that compaction is most likely carried up the wellbore during the drilling operation. Anything left behind is a minute layer (and I'm talking inches NOT feet) about the wellbore wall. It's not doing anything in the grand scheme of things...

That is simply not true. See below.

...I read your link. It was concerning California, and I'm not convinced. I'm not saying I'm discarding it, I'm just saying that there are a LOT of geographic factors taking place in California...now isn't there? I wouldn't call this PLENTY. But I will read anything further you submit.

Arizona Land Subsidence: Groundwater over-pumping and declining water tables.

13 feet of subsidence in Santa Clara County, CA

Most of the major subsidence areas around the world have developed in the past half-century at accelerated rates due to the rapidly increasing use of ground water, oil and gas.

Land Subsidence in the United States


Approximate location of maximum subsidence in the United States identified by research efforts of Dr. Joseph F. Poland (pictured). Signs on pole show approximate altitude of land surface in 1925, 1955, and 1977. The site is in the San Joaquin Valley southwest of Mendota, California.


Some of the most spectacular examples of subsidence-related earth fissures occur in south-central Arizona.


Homes at Greens Bayou near Houston, Texas, where 5 to 7 feet of subsidence has occurred, were flooded during a storm in June 1989.


This building at the Everglades Experiment Station was originally constructed at the land surface; latticework and stairs were added after substantial land subsidence.

external image
Collapse sinkholes, such as this one in Winter Park, Florida (1981), may develop abruptly (over a period of hours) and cause catastrophic damage.

The occurrence of land subsidence is seldom as obvious as it is in the case of catastrophic sinkholes or mine collapses. Where ground-water mining or drainage of organic soils are involved, the subsidence is typically gradual and widespread, and its discovery becomes an exercise in detection. Gazing out over the San Joaquin Valley, California today, one would be hard-pressed to recognize that fewer than 75 years ago the land surface was nearly 30 feet higher in some locations (fig. 2). Subsidence detection and mapping programs are critical to the scientific understanding and management of our land and water resources.

The detection of regional-scale subsidence has historically depended on the discovery that key bench marks have moved. Land surveys establish bench-mark positions to accurately locate roadways, flood and drainage-control structures, pipelines, and other engineered infrastructure. Once unstable bench marks are discovered, and truly stable bench marks have been established, subsidence can be mapped. This has traditionally been accomplished using spirit leveling and, more recently, Global Positioning System (GPS) surveys. A new tool has emerged in the past decade that has dramatically improved our capability to detect and map land-surface deformation.

This tool, interferometric synthetic aperture radar (InSAR), uses repeat-pass radar images from Earth-orbiting satellites to measure subsidence and uplift at unprecedented levels of spatial detail (80 m x 80 m) and measurement resolution (sub-centimeter) (Galloway and others, 2000) (fig. 10).

Once subsidence is identified and mapped, subsidence-monitoring programs can be implemented and scientific studies can be launched to improve our understanding of the subsidence processes. A combination of scientific understanding and careful management can minimize the subsidence that results from developing our land and water resources.

[img]

From my previous post:

Rapid subsidence over oil fields measured by SAR interferometry

Ground subsidence is a major worldwide hazard. One recent estimate placed the annual cost of subsidence damage and mitigation within the U.S. alone at over $100 million [National Research Council, 1991]. Relatively slow subsidence caused by the natural process of sediment compaction is widespread but seldom causes problems on human timescales. More rapid subsidence of the ground surface is usually attributable to human activities, such as the extraction of fluids from beneath the surface. Fast local changes in land elevation and associated surface strains can cause damage to structures that is costly to replace or repair, and can also greatly increase flooding potential.

Rapid ground subsidence over areas of petroleum and gas extraction has been observed previously [Mayuga and Allen, 1970; Pratt and Johnson, 1926; Vanhasselt, 1992]. The effects are most noticeable on a coastline where a small elevation decrease may cause inundation, first described over an oilfield near Houston, Texas [Pratt and Johnson, 1926]. Parts of the city and port of Long Beach, California, suffered major problems due to rapid (up to 0.75 m yr-1) land subsidence related to extraction of oil from the underlying Wilmington oil field [Mayuga and Allen, 1970]. Problems were caused both by inundation and by horizontal strains on the sides of the subsidence bowl. Subsidence over petroleum extraction zones can also cause significant damage to extraction infrastructure itself, including expensive well failures. In this paper, we report subsidence rates as high as 40 mm in 35 days or an annual rate of > 400 mm yr-1 in two California oilfields.

And...

Measuring Land Subsidence from Space

Land subsidence is a gradual settling or sudden sinking of the Earth's surface owing to subsurface movement of earth materials. Subsidence in the United States has directly affected more than 17,000 square miles in 45 states, and associated annual costs are estimated to be approximately $125 million.

Subsidence from Oil and Gas Production in Louisiana

Land Subsidence Research at NBMG

Subsidence.

The entire Goose Creek oil field in Texas sinking... Very interesting exhibit AND this involves oil drilling in Texas...

MAN-MADE SUBSIDENCE

Originally posted by Valhall
Are you speaking of wellhead pumping to extract hydrocarbons from a well that no longer can flow to surface? If so, yes, you are correct. That has nothing to do with this conversation. I stated that at some point the well would not produce at a profitable rate that include having to put a popping-johnnie on it or whatever. At some point the well will be closed in and P&A'd. period.

I still do not understand why you believe that has no impact on the geology of the field.

Originally posted by Valhall
You totally missed the point. The less the pore pressure the more dampening.

And the more subsidence/compaction (therefore, density), the less dampening?


On this unfortunate last matter...

Originally posted by Valhall
We are currently in a thread about a false threat based on a misinterpretation of research, and some one has offered up a solution to the factors you have brought up. Your response is to wave it off because of "other factors".

Cool! At least the original premise of the threat is not something that will kill us tomorrow, so I guess it is acceptable to wring our hands a bit longer on how to deal with GHG's. Meanwhile, we move on...blaming it on somebody else.

I'm not even sure what you are ranting about. Who is misrepresenting research on this thread? Really, Val, it sounds so paranoid and uncivilized......unfriendly...

And on a broader note: Does everyone, you believe wrong, harbor a secret agenda to perpetrate fraud? (That question probably should be left a rhetorical one. In other words, I at least hope that is not true.)

Again, let's keep it civil, please. I greatly respect your intelligence and like your input. It's the degree of your emotional restraint I'm less confident of.


[edit on 15-10-2005 by loam]

PODcast: GEEK ALERT: Quakes trigger Quakes (reply 5)
Reply covering down to Val's post at end of page 2. Edit note: on the point i disagreed with val on, i meant "resonance is not dependant
on amplitude, which is what she has said.

Originally posted by loam


OK, if the post production state is "caused" by man (drilling, mining & pumping), and that leads potentially to more impactful seismic events, isn't that the point of this thread? Shouldn't we more fully understand that?

loam, yes! But giving me a link of bibliographies concerning man's potential earthquake inducing activities, doesn't help with this discussion...which seemed to be (at one point at least) about how how we're leaving grand holes in the crust or permanently changing the properties of the reservoir rocks so it that could help a quake transmit to the surface more easily. These are two separate issue. If you'd like to redirect to how we can start an earthquake. Be my guest. And I say that with all due civility, by the way. I'm not arguing with you. It's just a separate issue.

quotes as you provided them above...

Thanks for these links. I'm going to look at all of them.

I still do not understand why you believe that has no impact on the geology of the field.

Well, since I've answered this, there's nothing more I can add.

And the more subsidence/compaction (therefore, density), the less dampening?

I don't know. Is this true?

I'm not even sure what you are ranting about. Who is misrepresenting research on this thread? Really, Val, it sounds so paranoid and uncivilized......unfriendly...

And on a broader note: Does everyone, you believe wrong, harbor a secret agenda to perpetrate fraud? (That question probably should be left a rhetorical one. In other words, I at least hope that is not true.)

Again, let's keep it civil, please. I greatly respect your intelligence and like your input. It's the degree of your emotional restraint I'm less confident of.

First off, I'm not ranting. Did that accusation come because I disagree with something here, or because I challenged that dismisisng a possible solution simply because it may not be perfected might not be the best action? If disagreeing equates to ranting, I guess I'll probably "rant" at some point in the future as well when we meet again. I don't believe I've done anything in this thread with you but have a discussion on the points you have brought up, right?

I don't think you have an agenda. At least I don't see one from where I'm sitting. I also haven't accused you of manipulating research. My statement was toward the fact that the original take on the reports referenced in this thread was based on a misinterpretation of what those reports said. So....??? Where'd that come from? I actually have no problem with anything you've said and I haven't been dismissive of any of it....other than refusing to go buy all the references on a link that is about another topic. I'm now going to go read your compaction links.


[edit on 10-16-2005 by Valhall]

loam

www.dnr.state.la.us...

That one right there is the one of greatest importance to me in the list of links you provided. A lot of the others tend to deal more with groundwater usage, and I'm not sure what the implication is when discussing groundwater usage. I surely hope it isn't that people shouldn't be using it.

The above link however is very informative and states that:

Surface subsidence results from the combined effects of the subsurface reservoir compressing or compacting a sufficient amount that it causes a displacement in geological formations above that are not strong enough to withstand the underlying structural force changes. If the changes in reservoir conditions are small enough or the upper geological structures are strong enough, surface displacement will not occur or will be only negligible. Reservoir compaction is a function of the extent of pressure reduction, the thickness of the producing zone, and the compressibility of the formation structure. Most reservoirs in which OGE has caused significant compaction consist of a sequence of unconsolidated sands and shales. Studies have shown that the amount of surface subsidence caused by reservoir compaction decreases with increasing depth of the reservoir from the surface and increases with the effective diameter of the reservoir and thickness of the reservoir. In other words, large scale subsidence results from special conditions such as large pressure declines in shallow, thick, large, highly compressible reservoirs. Production practices that include artificial pressure maintenance by gas drive or water injection counteract the reservoir compacting that would otherwise occur.

The preceding indicates that oil reservoirs produced by pressure depletion in loose sands or, and extremely large gas reservoirs in unconsolidated sands or friable rocks, are the types most susceptible to subsidence. This is indeed what Geertsma2 and Martin and Serdengecti3 found to be true in their studies, leading to the conclusion that other reservoirs are not a real concern in regard to surface subsidence.

So what we've got is the compaction of unconsolidated sand. It's packing. But it is not rock breaking down. I would agree that if you have a layer of unconsolidated sand that is compacted by overburden pressures after the zone's pressure has been decreased, it would become more transmissive of a wave than the uncompacted sand would have been before.

[edit on 10-16-2005 by Valhall]

TA

In reference to your podcast. We agree on the destructive nature of harmonic resonance being dependent on amplitude. My statement was ill-worded and should have read that harmonic resonance is not dependent on amplitude. The destructive force of it would be. Good correction, thanks!

About your statement on oil extraction. Please note that I said that by majority it being recovered from the porous, permeable rock is the case. There are exceptions where there are great pools (i.e. a vugular or cavernous reservoir). By majority the great pools were way in the past.

[edit on 10-16-2005 by Valhall]

Originally posted by Valhall
loam, yes! But giving me a link of bibliographies concerning man's potential earthquake inducing activities, doesn't help with this discussion...

Yes, I realize that. I should have posted when I had more time to explain the intention behind that list. But I did say "I found this excellent Bibliography on "Induced Earthquake" activity... Not clear whether it is directly on point, but certainly warrants further investigation."

Originally posted by Valhall

First off, I'm not ranting. Did that accusation come because I disagree with something here, or because I challenged that dismisisng a possible solution simply because it may not be perfected might not be the best action? If disagreeing equates to ranting, I guess I'll probably "rant" at some point in the future as well when we meet again. I don't believe I've done anything in this thread with you but have a discussion on the points you have brought up, right?

I don't think you have an agenda. At least I don't see one from where I'm sitting. I also haven't accused you of manipulating research. My statement was toward the fact that the original take on the reports referenced in this thread was based on a misinterpretation of what those reports said. So....??? Where'd that come from? I actually have no problem with anything you've said and I haven't been dismissive of any of it....other than refusing to go buy all the references on a link that is about another topic. I'm now going to go read your compaction links.

Fair enough. I now realize I simply misunderstood. Sorry.

Originally posted by Valhall
So what we've got is the compaction of unconsolidated sand. It's packing. But it is not rock breaking down. I would agree that if you have a layer of unconsolidated sand that is compacted by overburden pressures after the zone's pressure has been decreased, it would become more transmissive of a wave than the uncompacted sand would have been before.

Ok, so the next question is how big is this problem really?

(*ppppssst*-- This site (ATS) kicks ass. )



[edit on 16-10-2005 by loam]

Originally posted by Valhall
TA

In reference to your podcast. We agree on the destructive nature of harmonic resonance being dependent on amplitude. My statement was ill-worded and should have read that harmonic resonance is not dependent on amplitude. The destructive force of it would be. Good correction, thanks!

k, no prob Val, and the way you have just stated it there is spot on. You just said in two sentances what took me half a bumbling podcast to explain! lol. Val is Val. Ain't no substitutes.

About your statement on oil extraction. Please note that I said that by majority it being recovered from the porous, permeable rock is the case. There are exceptions where there are great pools (i.e. a vugular or cavernous reservoir). By majority the great pools were way in the past.

K, understood.

Ok so now, Soficrow- in regards to your first podcast in this thread, and the question of whether undergound chambers could amplify seismic waves, can we all come to some kind of agreement here that the larger the chamber the more it will impede the wave at all frequencies? That seems to be the cummulative consensus, unless I have missed something, or someone else would like to chime in on the issue...I'm all ears. They don't call me dumbo for nuttin ya know

Smile everyone. You are more appealing that way.

PODcast: GEEK ALERT: Quakes trigger Quakes (reply 6)
Responding to discussion

length: 10:09
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Thank you all. You guys are great - and you are doing some really GOOD work here. I appreciate it - and I know everyone else does too. I'm learning a lot from you. Again, thank you.

Do quakes trigger quakes? Well, it's fairly clear that they can do. Not always, but certainly, sometimes. More important - one quake can trigger another "remotely" - that is, remote meaning geographically distant, and ALSO, remote in terms of TIME. We may not see an acute geological impact until years later, in a completely different place.

So - why IS that?

Well - our planet is a system - like the old explanation of chaos theory says - a butterfly flapping it's wings in Peking can cause a snow storm in Toronto.

...Does that really happen?

Not really - it's more of an analogy - but what the butterfly story illustrates is very important. It means that even very small things can impact large systems in unpredictable ways, and in ways that are totally out of proportion to the originating event.

It means that an event as minor as a butterfly flapping its wings can set off a sequence of events - a cascade - that may result in a HUGE reaction, thousands of miles away, and sometimes - decades down the road.

The butterfly story emphasizes the importance of looking at events as part of a systemic process - a process that involves systemic response, adjustment, and adaptation. Nothing much in this world - really - occurs as an isolated circumstance, involving one direct cause and a single effect.

The truth is - we just don't SEE the mini-events that contribute to creating cascades that result in earthquakes or volcanic activity. We don't see them partly because we don't know what to look for - but also, we don't identify the minor events and contributing factors simply because we just DON'T LOOK. We don't WANT to see them. It's the ostrich syndrome - in action. And yes - absolutely - there are forces in play - and powers - that want to keep our attention directed elsewhere.

It’s really important to me that we focus here on humanity as a whole, and our planet. And not be distracted by corporate concerns – of liability or profit or anything else. Corporate pseudo-scientific legal arguments already get plenty of airtime on other media. This is OUR turf.


In this thread - My first premise is that what we do affects the earth - in this case, geologically. There is lots of scientific evidence – but more - it's just good common sense. You do anything to a piece or part of a system - you affect the WHOLE system.

It’s really simple – but maybe – too obvious.

***I mean - like - go put some make-up on your carburator - make it LOOK nice. Ummmm, I'm not sure if you should use oil or water - based makeup. But it looks BAD – like - you need to do SOMETHING. And, uh, tell me how it works, after the makeover.


So my main question here is - How? How are we affecting our planet's geology – its geological system? Let's look at the various things we have done - and consider the possible effects.

But no - I do not expect to find proof of direct cause and effect relationships. It's not going to happen - because that's NOT how systems work.


As TrueAmerican says - we are not anywhere near addressing the complexity of the situation. We still are looking at isolated factors - and mainly, we are looking at these factors IN isolation. So we still have a ways to go.

Certainly - compaction is a factor. As is soil and rock conductivity, and man-made changes in conductivity. Then we have amplitude, and frequency. And we need to consider the different KINDS of seismic waves. There's a lot to think about - assimilate - and integrate.


One of the big controversies here on this thread comes out of the question - Have we created underground echo chambers that increase the amplitude of seismic waves?

Just to clarify - That question was a "teaser" - and I don't apologize. It needed to be simple to fit with the podcast format. It simply directed attention, and opened enquiry – as it was meant to do.

True American addressed the question in his first response - and clarified that under certain conditions, seismic wave amplification MIGHT take place. He specified that numerous factors are involved - including the size and shape of the chamber, and the material creating the chamber.

Valhall reiterated that the Los Alamos study shows that specific amplitudes impact specific materials. If I'm not mistaken, she also claimed that empty underground chambers always serve as baffles, and always - or almost always - attenuate both frequency and amplitude.

Now loam is asking - Can we agree that the larger the chamber, the more it will impede waves at ALL frequencies?

My answer - loam - is - no. First off - In spirit - the question is meant to be bigger than that. But - I now am more inclined to think that CERTAIN now-empty underground chambers might in fact amplify seismic waves. In any event - whether or not the waves are amplified - CERTAIN chambers may direct - or redirect - seismic waves to new locations.

What if? - What if a seismic wave originating in Wyoming travels through the now-empty Ogallala Aquifer to New Mexico, or Texas - and bumps into a rock wall barrier that just happens to resonate with that seismic wave? What happens next? What’s the impact?

The Los Alamos study says - the key factor is amplitude, for one quake to cause another - and found that specific amplitudes impact specific materials. Everyone here seems to be saying frequency is critical. So what other factors might influence the outcome?

And what happens whjen we go outside the identifiable geological system to consider other, and apparently unrelated factors? Like magnetic radiation? Might waves of magnetic radiation be a factor in this planet's systemic seismic activity?


Regarding induced quakes. I have to ask - Are induced quakes really isolated events? Unrelated to anything that might follow? Or are they equivalent to a butterfly flapping its wings?


TrueAmerican - you state that a quake only could trigger a quake in the same fault line. I want to draw your attention to an ATSNN article written by FredT - titled -
Asia Quake Impacts Virginia Well-Water Levels

So my question to you is - if the Asia quake could impact Virginia well water - what's stopping it from doing something else?

And I wanna know - how the heck DID that happen?


Also – TrueAmerican - your idea of digging foot wide trenches around cities - to act as baffles to stop seismic waves - and protect cities from earthquakes’ worst effects - now THAT'S an interesting concept. Worth investigating, I’d say.


Okay - that's it for now from me. Great stuff guys - keep it comin.

Originally posted by soficrow
Now loam is asking - Can we agree that the larger the chamber, the more it will impede waves at ALL frequencies?

Actually, soficrow, that is not entirely correct. In fact, I posed this question in one of my previous posts to this thread:

Originally posted by soficrow
Now on the issue of sound waves in larger cavernous voids, I would ask whether there is any localized effect caused by these sound waves? Could these effects contribute to the destabilization of the overall structure of these voids?

I think TA partially answered this question in that while such voids might "dampen" the the transmission of a wave to other locations in the strata, the effect upon the void itself is altogether a different matter.

I may have misunderstood, but I assumed this implied that such sound waves could cause the potential collapse of certain voids. In keeping with your "butterfly effect" analogy, I'd imagine that the collapse of a void caused by a distant seismic event could in itself extend (through a loose notion of causality) the reach of the initiating seismic event- very much like one domino hitting another, and so on.

BTW, everyone. I keep thinking of this picture... Isn't that amazing?!

Sorry if I misunderstood, loam. Thanks for clarifying - and thanks for keeping this discussion going, on track.

INSERT EDIT - I am REALLY sorry loam. Just scanned back. It was TrueAmerican who asked that question. Mea culpa.


...So - you're saying that one impact of a 'rogue seismic wave' might be the sudden collapse of a void (or now-empty underground chamber), right?

...Brain burp - I cannot remember the term for those big holes that keep opening up all over...? Can you help me out here? And do you think they might be related, sometimes?


That pic is GREAT! Thanks for posting it. Looks like the ground level in the San Joaquin Valley has dropped by what? maybe 30 feet in the last 70-odd years? ...and that area is above what? the now-almost-dry underground Colorado River?

...So if that drop happened suddenly, what kind of cascade might follow? Would the final impact be greater than the sum of its parts?



.



[edit on 17-10-2005 by soficrow]


Mod Edit: to remove BIG Quote

[edit on 17-10-2005 by kinglizard]

Originally posted by soficrow
...So - you're saying that one impact of a 'rogue seismic wave' might be the sudden collapse of a void (or now-empty underground chamber), right?

...Brain burp - I cannot remember the term for those big holes that keep opening up all over...? Can you help me out here? And do you think they might be related, sometimes?

Do you mean sinkholes? I'm not sure. It sounds possible.

Originally posted by soficrow
That pic is GREAT! Thanks for posting it. Looks like the ground level in the San Joaquin Valley has dropped by what? maybe 30 feet in the last 70-odd years? ...and that area is above what? the now-almost-dry underground Colorado River?

...So if that drop happened suddenly, what kind of cascade might follow? Would the final impact be greater than the sum of its parts?

Actually, I am now convinced that sudden drops are less relevant (because they are more rare) than the issue of subsidence. Since it now appears we all somewhat agree that compaction will facilitate the transmission of sound waves more so than would have been true prior to compaction, the question becomes have we unwittingly made some areas more vulnerable to the effects of seismic waves because of such subsidence?


[edit on 17-10-2005 by loam]

Originally posted by loam

...compaction will facilitate the transmission of sound waves more so than would have been true prior to compaction, the question becomes have we unwittingly made some areas more vulnerable to the effects of seismic waves because of such subsidence?

Okay. Sounds like a good direction. Do you happen to have any relevant maps in your back pocket?

...or any comments on the notion of whole system adjustment and adaptation?