Thermonuclear Fusion, as a Source of Seismic Phenomena?

[serguei58]

Gentlemen, the question of determining the source of energy of earthquakes is included in the UN list of the 10 most important tasks of mankind. I propose to discuss my article on this issue: https://papers.ssrn.com/sol3/papers.cfm ... id=3498657

Thanks

[serguei58]

Are there really no questions for the author of the work?

[vikingpeggy]

1. The power of thermonuclear reactions is not limited. Examples of thermonuclear reactions on the Sun confirm this and remove all doubts.
2. Mechanical energy can be represented as the work of spring, and it is difficult to imagine a mechanism that stores and implements an energy level of 200 megatons. Don't you think?
3. How to explain the origin of deep-focus earthquakes at depths of 300-800 km by mechanical energy, where everything is in a semi-molten form?

[serguei58]

I completely agree with you, terrestrial rocks are incapable of storing mechanical energy. The accumulation of mechanical energy is contrary to the fundamental laws of physics.
This is what I am writing about in my article.

[GuyM]

"terrestrial rocks are incapable of storing mechanical energy"

Can you expand on this in terms of the what we know about elastic moduli of rocks from both rock physics laboratory measurements and modern exploration seismology?

[serguei58]

Everything that we know from the results of testing rock samples should be forgotten like a bad dream because we can apply Young's modulus only to isotropic samples of small size. It's about centimeters. How can we apply Young's modulus to samples measured in kilometers? It's monstrous, but scientists are still trying to calculate the mechanical energy of tectonic plates based on Young's modulus. They receive numbers, substantiate them, but these numbers do not mean anything, because the modulus of elasticity can vary in their calculations from 0 to infinity.
In this work, I substantiated some of the provisions of the accumulation of mechanical energy by the rocks of the earth's crust.
https://papers.ssrn.com/sol3/papers.cfm ... id=3519627

[GuyM]

"Everything that we know from the results of testing rock samples should be forgotten like a bad dream because we can apply Young's modulus only to isotropic samples of small size."

Well, we see the self-same issues with measuring seismic velocities from core (or using sonic logs) and the velocity data we get from reflection seismology in processing. Yet we can calibrate these measurements and use them effectively for a sorts of purposes, linking the micro-meso and macro scales in exploration seismic.

So I'm not quite prepared to say that lab-based rock physics measurements have zero value when it comes to reflection seismology. How much we understand about the deeper earth's crust is a whole different game. No samples, just sparse data from distant quakes to invert an dplay with.

That's why I'm interested in reflection seismic data - better sampling of the waveforms and better well control.

Still - what predictions do you make and how well do they match observations in a blind test? Plenty of earthquake data available....

[serguei58]

I agree with you that we can use seismic velocity data and use it in exploration seismic. But then again, we cannot trust these numbers. The fact is that we get average indicators of their distribution in the rocks of the earth's crust, and these indicators are very high and almost do not differ from each other, for example: 100 m / s in one direction, 200 m / s in the other. What's the difference in calculations?

[GuyM]

I'm unsure what you mean by "trust these numbers"?

Every measurement - direct or indirect - has a limiting accuracy based on a range of constraints, and velocity analysis is no exception.
Manual analysis is one thing, however when you start to get into semi-automatic high density velocity analysis that is something else. Modern techniques can take you even further when you start to include tomographic analysis, FWI and so on.

My own experience with brute-force semi-automated high density velocity analysis is that the variation matches with calibrated velocity logs (derived by correcting sonic logs for shoulder effects and using checkshots to correct for the "drift" associated with the frequency variation between techniques) very well; colleagues have taken that work into the detailed study of methane clathrates and so on a few years ago. So yes, I trust those numbers within the constraints of the technique we used, as they tie to observations well. At least in the geologies where I used them...

Full Waveform inversion techniques continue to push towards more accurate representations of velocities in conjunction with improved imaging, and so on, and this is heading into elastic full waveform inversion.

No matter what we do, however, we only have models, that either make useful predictions (which we keep) or do not (which we reject or modify); overall the entire concept of a p-wave velocity is a mathematical approximation of how seismic waves travel in bulk. With the exception of (maybe) halite, rocks are not homogeneous or isotropic - there are fractures, faults, changes in grain size or geochemistry and so on.

From a seismological point of view GNSS stations and radar interferometry over time can give a picture of accumulated stress at the surface; not my specialisation but there's a lot of work done on immediate aftershock forecasting after a major event, which is critical to the disaster response; and you that's still pretty emergent depending on what data is known about the fault system and so on, and the lack of sub-surface data.

If you really are aiming at "stress and strain accumulation play no role in earthquakes" then I'd suggest your approach needs to be able to delivery better stochastic forecasts of aftershock sequences than other techniques; that is to say there's a set of predictions from you model, and those can be matched against observed data in a "blind" way.

Got woken at 4:52 am by a M4.2 located < 20km from my house (and about 25km depth) this morning, and some tens of KM below my feet the Pacific Plate subducts under the Australasian one, so this is not just academic interest on my part!

[serguei58]

Good morning and Happy New Year! I understand you perfectly. My remark regarding "trust these numbers" concerned the determination of mechanical stresses in tectonic plates and did not concern the study of the internal structure of the earth's crustal rocks. Seismic velocities are very important in obtaining tomographic analysis. Thanks to the latest advances in science, we can look inside the Earth. Nobody is against it. My position is different, in no way we CANNOT use the physical and mechanical properties of rocks to calculate the stress-energy!