Quakes trigger Quakes

Originally posted by Valhall
Well, we need to hurry and get this new science out then, because there are a lot of geologists and seismologists that are tremendously misled.

Precisely. And that's exactly what we're doing here.

They've been operating off the fact that the greater the density variation between two media at a boundary layer, the greater the reflection angle and the less transmitted through the less dense media.

And they've been focusing exclusively on frequency, not amplitude. This old science assumed that the key was frequency, while the new work shows that amplitude is what's critical.

Furthermore, they've been under the impression that S-waves can't even be transmitted through fluids, so they're in a heap of a mess on that one.

EXACTLY. The fluids have been removed. Part of the equation involves dehydration impacting conductivity.

I contend that if we had a giant layer of honeycombs there'd be no way for a quake to transmit from one point on the earth to another...it would just bounce about inside the earth losing a bit of energy each time it reflected against one of these baffles, until it completely dissipated.

But that's because I'm deeply entrenched in the old science.

Yes. You describe what's called a negative feedback loop, where the assumption is that the energy dissipates as frequency is attenuated.

The study referenced above shows that the earth's response is a) NON-linear; b) unpredictable; and c) appears to involve positive feedback loops, not negative ones - and that amplitude is the critical factor, not frequency.



.

Interesting, Crow!
What universities are teaching this, now? Where can you pick up the new teaching?

TC

Apparently the universities that have chosen to throw away hundreds of years of empirical data and all the governing equations for vibrations, acoustics, and wave transmissions through varying media.

Apparently universities that when they look at seismic log data that shows tremendous reflectivity in waves when a pipe is backed by nothing but an air gap, versus very low reflectivity when it's back by a media close to the pipe material they just say POPPYCOCK! I don't care what that shows, I've decided it's opposite day!

After all - nothing is sacred when you're trying to mislead the masses for the sake of your own agenda - not history, not science...nothing. Bad science and false history are fair weapons in pushing the big message.

*you gotta get some gotta gotta get some - DISINFORMATION!*

(I thought I told you both that you're not allowed to play together?! )

OK...

Valhall, you state:

Originally posted by Valhall
One thing that complicates it further, and tends to weaken the reports referred to originally, is that let's say for this map



it' very easy to jump to the conclusion that we've got this huge plane of orange that now has a "layer" that is some how weakened by the oil extraction. The problem is, it's not showing you the area in 3D. All those areas in orange are at different depths. So it actually isn't a plane. It's very discontinuous "spots" where oil or gas as been produced. One field's producing zone might be at 20,000 ft and the other might be at 3,000 ft. So the orange doesn't actually "connect together"

Hope that made sense.

EDIT: Corrected pre-coffee homonymal dysfunction.

It did make sense. If you think of a "block" of swiss-cheese, rather than a slice, I think the analogy still holds pretty well. Except perhaps, that some holes are vacant and others are filed with porous material (I assume sedimentary rock) that is 'dehydrated' or potentially re-hydrated by water.

I found this excellent Bibliography on "Induced Earthquake" activity.

Induced Earthquake Bibliography. Not clear whether it is directly on point, but certainly warrants further investigation. Here are a few of the bibliographic sections:

Induced Earthquakes in General (6 references)
Injection Induced Earthquakes (116 references)
Rocky Mountain Arsenal quakes
Reservoir Induced Earthquakes (127 references)
Oil & Gas Production Induced Earthquakes (48 references)
Geothermal Energy Extraction Induced Earthquakes (38 references)
Mining and Quarrying Induced Earthquakes (89 references)
Nuclear Test Induced Earthquakes (20 references)
Seismicity Related to Underground Gas Storage (7 references)
Legal Implications of Induced Earthquakes (13 references)
Miscellaneous References (21 references)
Newspaper & Magazine References
Links to other induced seismicity webpages

My time is limited right now, but I will post later some other interesting material I have found.

[edit on 15-10-2005 by loam]

TO CLARIFY:


This discussion is about the groundbreaking results of two recent studies on earthquake dynamics, recently published in Nature magazine. The two studies were jointly funded by France and the US Department of Energy - and involved heavy scientific hitters from places like the Los Alamos National Laboratory. For example, Paul Johnson is a geoscientist at Los Alamos National Laboratory, and a co-author of both Nature papers.

Valhall' and ThomasCrowne's opinions presented here reflect the standard industry response, which is designed simply to avoid charges of liability - but does not accurately reflect contemporary scientific knowledge. My recommendation, V and TC: if you have difficulty accepting the studies' results - you should go directly to the source: in the USA, that would be the US Department of Energy and/or the Los Alamos National Laboratory.

For purposes of this discussion - my hope is that we can accept the studies' results and observations as valid, and proceed from there - and avoid non-productive, essentially political distraction.

The key discovery is that amplitude, not frequency, is the critical factor that causes one earthquake to trigger another.

TrueAmerican's, loam's, and my responses all focus on the implications of, and possible explanations for, this factor and the resulting dynamic - with respect to physical sciences. nrky addressed issues of social/political significance.

Study: Quakes Trigger Quakes

...They discovered that the materials didn't react to the frequency of the seismic vibrations, but were weakened as a whole when hit by shocks exceeding certain seismic strengths, comparable to the "loudness" of the seismic waves.

The sudden weakening at key amplitudes, instead of gradual weakening as amplitudes steadily increased, is why they describe the triggering as nonlinear, Johnson explained.

...To see if the laboratory finding could be applied to real earthquakes, Johnson teamed up with the U.S. Geological Survey's Joan Gomberg to see which sorts of historical quakes seem to be triggering other tremors.

They compared records from a number of remotely triggered quakes and found that the most important factor was amplitude, not frequency, just as in the laboratory.

.

loam

Thanks for the list. But you do understand that's a totally different issue, right? Those links are talking about earthquakes induced by drilling, producing, mining activities and seismic testing. Not about natural earthquakes being able to amplify or transmit better to another portion of the earth's surface due to the after effects of what oil production does to the reservoir.

I fully support the idea that drilling, mining and seismic testing could induce earthquakes. In fact, I believe in one of the threads concerning the Indonesian quake that we actually discussed an article found that talked about some seismic testing that had been taking place in the area just prior to the big quake.

I'll try to find that old article and post it here. Just want to make sure you understand I am not arguing against the possibility that certain actions could induce quakes. What I am arguing against is that an air chamber would act as a better transmitter of a seismic wave than continuous rock. If you place an air chamber in the path of a wave you are going to decrease the wave transmission to the next layer of "solid media". Every time! It's a baffle!

Concerning statements made prior about the change in rock properties due to production. You don't actually leave the pores of the rock empty. The fluids are stacked according to their density, just as they would be in a glass. You've got gas on top, oil in the middle and water below. As you produce a zone (whether it be gas or oil) the fluids will migrate (unless there is an impermeable barrier between them) up the reservoir. That's why eventually oil wells start producing water. So you haven't really left the rock empty, you've just changed the filler in areas.

But let's just say, for the sake of argument, that all your little pores in your rock were left dry. That rock would be less likely to transmit a wave on upward toward the surface than a rock with pores filled with water or oil. The more "compressive" the fluid filling a pore is, the more it will absorb the energy in an "echo chamber" type style and not transmit the energy on up. Again, a little bitty baby baffle.

It's a matter of elasticity and compressibility really and that's why we play ping pong with a hollow ball and a rubber-matted paddle versus with a ball bearing and a metal paddle. It just wouldn't be as much fun because the vibration caused by the impact of the ball bearing would be transmitting straight to our arm and the ball wouldn't go anywhere - but down. The vibration would be passing on due to a near perfect inelastic collision. There's no elasticity and compressibility to absorb the wave caused in the collision.

[edit on 10-15-2005 by Valhall]

I've got one more example, and then I'm leaving this thread behind, because I've attempted to give real-life examples so that no matter what level education any given reader might be at, they could take at least one example away that might make sense to them.

Let's say I have a centrifugal pump with a metal housing and it's not outputting like it should. So I'm going to try to diagnose whether it's got a mechanical problem, or if it's a hydraulic problem.

If I stand at this pump and listen as it runs I most likely would not be able to hear if the pump was cavitating or if it had a bad bearing. But if I take pipe wrench and I place that pipe wrench say, on the suction manifold of that pump, and then I place the handle of the pipe wrench on my temple - I can HEAR cavitation. If I place that same pipe wrench on the power end of that pump I would be able to HEAR a bad bearing.

Why?

Because the metal of the pipe wrench and the bone in my wee li'l noggin transmits energy waves better than the sucky compressible air the sound has to go through before it reaches my ear drum. By letting the wave travel through a series of materials that are close to each other in transmission properties, we have cut out the "muffling" nature of the air the sound would have to travel through to get to our eardrums.

The same thing happens when you think of a wave transmitting from a layer of rock to a layer rock versus rock - air chamber - rock.

Crow, you are assuming I have an opinion on this, and again, you are in error.

Unlike you, I do not pop off with "knowledge" when I am ignorant. When I am ignorant, I ask questions. I simply asked a question, and believe it or not, you gave an answer when you stated from what journal it was reported and who were the parties researching this.

I do not assume that because you do not let your ignorance in American government stop you from spreading disinforamtion means that you haven't a clue about this topic. I was simply asking a question because I am ignorant and wanted information.

Thanks, Val, for the additional inforamtion. I am aware of your personal background, training and profession, and I know that you aren't simply passing on information you've picked up from the internet. All of the collected data is important.

So now this brings up the argument of the resonance capabilities of air in different states:
1. Differing pressure states, ie. vacuum, atmosphere, concentrated gas, etc.
2. Differing temperatures of the air.
3. Convection forces present in the air.

To argue whether or not air and othe gases act as efficient conductors, or dampeners, is to consider these three principles.

Is the air in a porous rock at the same temperature, pressure, and velocity as that of the air in a water pump, or the air in the upper stratosphere?

Originally posted by Thomas Crowne
I do not assume that because you do not let your ignorance in American government stop you from spreading disinforamtion means that you haven't a clue about this topic.

TC, you should not have even been contemplating the thought of bringing this up, this theory about Soficrow's political agenda has NO importance in this podcast thread. Could you people PLEASE, for the LOVE OF GOD, PLEASE stop bringing up crap from pre-existing arguments between members.
THE REST OF US ...DO ....NOT .....CARE!

So please keep this podthread in relation to quake resonance theories.

"Can't we all just get along??"

PODcast: GEEK ALERT: Quakes trigger Quakes (reply 4)
Responding to discussions.

length: 04:22
file: atspodcast_579.mp3
size: 1590k
feed:
status: live (at time of posting)

Originally posted by nrky
So now this brings up the argument of the resonance capabilities of air in different states:
1. Differing pressure states, ie. vacuum, atmosphere, concentrated gas, etc.
2. Differing temperatures of the air.
3. Convection forces present in the air.

To argue whether or not air and othe gases act as efficient conductors, or dampeners, is to consider these three principles.

Is the air in a porous rock at the same temperature, pressure, and velocity as that of the air in a water pump, or the air in the upper stratosphere?

The air/gas/liquids in the rock are at greater pressures (and temperatures) than surface. They are still less dense, and less transmitting, than the surrounding rock. But also, since the theory is DEPLETED reservoirs, the pore pressure in the rock AFTER a zone has been depleted is less than it was before it was produced. So, pore fluids only becomes less compressed, more compressible, (i.e. more dampening) once it has been produced.

Val - I think you're right re: oil reservoirs and the "echo chamber" idea. ...But oil drilling still can be a problem re: dehydration, and also, simply by changing the composition of the earth's materials - which will have an impact if only by requiring rebalancing. (Conductivity is a big issue here tho, I suspect.)

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.

...The general idea is that we have been messing with the earth's geology - and now it's messing back. ...We're just looking around.

You said earlier that you thought we agreed on something or another - and we did (whatever it was). ...I think we agree on several key points - if not here specifically, then elsewhere. I've just read several of your posts that I agree with 100% - and think are dynamite. ...Not sure where our communication breaks down. But I expect that we will sort it out. Altho it may be continue to be a painful process.



.

TC:


Valhall:

Originally posted by Valhall
loam

Thanks for the list. But you do understand that's a totally different issue, right? Those links are talking about earthquakes induced by drilling, producing, mining activities and seismic testing. Not about natural earthquakes being able to amplify or transmit better to another portion of the earth's surface due to the after effects of what oil production does to the reservoir.

Yes, but I think the issue is related, I just didn't have time to fully explain.

The fact that there is such seismic activity, resulting from drilling and mining, stands as direct evidence of a change in the geological characteristics of an area. The question becomes, do we really know how it has been changed? In other words, what new physical characteristics does the resulting geology have and how does it behave in light of soficrow's material?

Originally posted by Valhall
I fully support the idea that drilling, mining and seismic testing could induce earthquakes. In fact, I believe in one of the threads concerning the Indonesian quake that we actually discussed an article found that talked about some seismic testing that had been taking place in the area just prior to the big quake.

Agreed. And here is additional material that supports such seismic effects:

Induced Seismicity

Induced seismicity describes earthquakes that in one way or another are related to human activity. They can be divided in two types:

Triggered. This group of earthquakes are caused by tectonic stresses. They would probably have occurred sooner or later, but their proximity to to human activity in time and space indicates antropogenic activity.
Truly induced. This group of earthquakes are purely antropogenic in that stress buildup can be traced directly to human activity.
For convenience we use the term `induced' for both types.

Earthquakes are mainly induced in three antropogenic settings, (1) in mines, (2) in connection with large water reservoirs and (3) in oil or gas fields where hydrocarbons are extracted. Furthermore earthquakes are induced in hydrothermal fields, but since this industry is young compared to the three above less data exist.

more...

Seems clear.

Originally posted by Valhall
What I am arguing against is that an air chamber would act as a better transmitter of a seismic wave than continuous rock. If you place an air chamber in the path of a wave you are going to decrease the wave transmission to the next layer of "solid media". Every time! It's a baffle!

I think you are right about that, but does it invalidate the broader question of whether the resulting geology- whatever that is- potentially 'amplifies' (lay sense only) the intensity of any seismic activity?

Originally posted by Valhall
Concerning statements made prior about the change in rock properties due to production. You don't actually leave the pores of the rock empty. The fluids are stacked according to their density, just as they would be in a glass. You've got gas on top, oil in the middle and water below. As you produce a zone (whether it be gas or oil) the fluids will migrate (unless there is an impermeable barrier between them) up the reservoir. That's why eventually oil wells start producing water. So you haven't really left the rock empty, you've just changed the filler in areas.

I agree this occurs, but there is no indication that that is uniformly true of all drilling locations. In fact, there is plenty of evidence of "compaction" (which logically results from 'dehydration' and/or a loss of pressure of the porous material) in drilled oil or gas beds.

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...

Conclusions
We have used interferometric analysis of spaceborne ERS SAR to map the subsidence of the surface over oilfields in central California. We measure very rapid subsidence rates of up to 400 mm yr-1 or >1 mm day-1 (Plate 3), and show the subsidence is largely limited to the petroleum production properties (Figures 1 and 2). In the Lost Hills oilfield, preliminary elastic strain modelling using an implementation of the Okada [1985]model [Feigl and Dupré, in press] indicates a net compaction of 1.7 mm day-1 at the center of the subsidence bowl decreasing to 0.6 mm day-1 to the south. That much compaction over a total area 0.8 x 5 km could account for the observed surface subsidence of the 35-day interferogram (Plates 1 and 3). This modeling shows that the volume change in the rock units at depth sufficient to cause the observed signal is roughly 1.5x106 m3 yr-1 for the Lost Hills oilfield. More detailed modelling of the deformation in the fluid reservoirs [e.g., Segall et al., 1994] would require data on pressure changes within the reservoir from the operating companies...

Here is graphic showing what subsidence looks like.



(Found here.)

Notice the yellow layer?

While it is doubtful that "an air chamber would act as a better transmitter of a seismic wave than continuous rock," you have to agree (and you state as much) that the opposite is true in more 'solid' (again, in a lay sense) conditions. Isn't that the resulting physical condition of subsidence?

Originally posted by Valhall
But let's just say, for the sake of argument, that all your little pores in your rock were left dry. That rock would be less likely to transmit a wave on upward toward the surface than a rock with pores filled with water or oil. The more "compressive" the fluid filling a pore is, the more it will absorb the energy in an "echo chamber" type style and not transmit the energy on up. Again, a little bitty baby baffle.

I have to agree, at least with regard to the transmission of sound through porous material. But that assumes it remains in that state. Once that state changes to a more solid profile (compaction), it seems to support the broader question raised concerning whether drilling has a probable effect on the intensity, reach, or impact of seismic events.

Now on the issue of sound waves in larger cavernous voids, I would ask whether there is any localized affect caused by these sound waves? Could these effects contribute to the destabilization of the overall structure of these voids? And, if so, could there be a cascading effect beginning on a smaller scale and ending on the larger?

(I've run out of time again... )



[edit on 15-10-2005 by loam]

I don't think we can extrapolate the potential to cause minor quake activity via sub-surface activities to the POST-production state of the reservoir and then jump over to - and so quakes will transmit better afterwards. No, I don't see that connection at all. The quake inducing activities (which by the way, we can only say MAY cause quakes not definitively DO cause quakes) would be through a dynamic vibration-inducing event. It has nothing to do with later reservoir-rock property changes.

As far as talking about "compaction". I'm not going to sit here and say there couldn't be ANY compaction EVER, but it would be highly unlikely. Primarily because once a reservoir is depleted down to where the pore pressure no longer can produce the hydrocarbons up to the wellhead, the well is P&A'd. The hydrocarbons are going to continue to produce (at an unprofitable rate) into the wellbore until the pressure below the plug in the wellbore and the reservoir equalize. So it doesn't go to "zero" is basically what I'm saying. You're still going to have both pore pressure - not a vacuum in the little pores.

Compaction, if you mean destruction of the pore spaces and breaking down of the matrix of the rock, isn't very likely.

P.S. loam - if you ARE concerned there could be compaction due to decreased pore pressure, then you need to support CO2 sequestration in depleted oil fields.

Two birds - one gas. LOL!

Val-

What DO you think accounts for amplification - in both layman's language and scientific terms? If you can pull that off - I know it's not always easy.

Also - do you think the role of amplification in causing a seismic response is new? Or just "previously undiscovered"?

Thanks - sofi

Okay, first off, the best I can tell by reading the two links at the upper portion of your post of many links on the first page, is that you are mis-reading one particular statement from one article. That article is linked here:

dsc.discovery.com...

The portion I believe you are misinterpreting is the following:

The sudden weakening at key amplitudes, instead of gradual weakening as amplitudes steadily increased, is why they describe the triggering as nonlinear, Johnson explained.

This is not saying that amplitudes increase for a given seismic wave from a given seismic event. It is saying that there are KEY amplitudes that decrease rock strength. Those key amplitudes are actually at a lower amplitude level than (I'm assuming) they suspected. In other words, there is a key amplitude in which you do the most destruction to rock when the wave hits, and it's lower - not higher.

The article does NOT state that amplitudes increase for a given wave propagating through the earth.

There's only three parameters to a wave:

amplitude
wavelength
frequency

The amplitude is set by the energy at the point of initiation (in this case epicenter of the quake). The other two parameters are established at that point as well, but are dependent on the media in which the wave is traveling.

So when you move to a new medium, the wavelength and frequency will change, but must keep the "wave function" or "wave number" constant for that wave. Your frequency will go up or down and your wavelength will show the inverse behavior of your frequency.

The AMPLITUDE - in a perfect universe where no energy is lost (entropy) - will remain the same. But we don't live in a perfect world. So as the wave travels through from medium to medium it is losing energy. The energy is taken from its amplitude.

A wave will ALWAYS decrease in amplitude as it travels from medium to medium. The only thing that can cause an amplitude to INCREASE, is an additive situation. That's a situation where you set up a new wave that is increasing at the same time the original wave is increasing and they add together. Where as any other wave interaction will cause some measure of interference (i.e. degradation).

And the worst case scenario for additive waves is harmonic resonance. Where you hit a frequency (not amplitude dependent) that is the "natural frequency" of a system. At that point - things will completely shake apart in a system. Because the waves have gone to a state of catastrophic increase.

But neither of the above situations is what the article is referring to. 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).

[edit on 10-15-2005 by Valhall]

And P.S. I think this is very interesting and I hope these scientists get to research further. Because this could be a future way to forecast "subsequent" quakes when a particular quake causes a seismic wave that has this destructive amplitude.

Originally posted by Valhall
I don't think we can extrapolate the potential to cause minor quake activity via sub-surface activities to the POST-production state of the reservoir and then jump over to - and so quakes will transmit better afterwards. No, I don't see that connection at all.

I can't see why not? 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 quake inducing activities (which by the way, we can only say MAY cause quakes not definitively DO cause quakes)

I can agree with that, but there is compelling evidence otherwise.

...would be through a dynamic vibration-inducing event.

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

It has nothing to do with later reservoir-rock property changes.

How did you get there? Are you saying seismic activity can't lead to additional compaction?

As far as talking about "compaction". I'm not going to sit here and say there couldn't be ANY compaction EVER, but it would be highly unlikely.

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?

Primarily because once a reservoir is depleted down to where the pore pressure no longer can produce the hydrocarbons up to the wellhead, the well is P&A'd.

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

The hydrocarbons are going to continue to produce (at an unprofitable rate) into the wellbore until the pressure below the plug in the wellbore and the reservoir equalize.

Which takes how long? The article I posted earlier clearly shows rapid compaction.

So it doesn't go to "zero" is basically what I'm saying. You're still going to have both pore pressure - not a vacuum in the little pores.

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

Compaction, if you mean destruction of the pore spaces and breaking down of the matrix of the rock, isn't very likely.

If this statement is true, then how is compaction possible?

Originally posted by Valhall
P.S. loam - if you ARE concerned there could be compaction due to decreased pore pressure, then you need to support CO2 sequestration in depleted oil fields.

Two birds - one gas. LOL!

This has other concerns...


[edit on 15-10-2005 by loam]