The research showed that the release of frictional forces begins with a wave moving at the speed of sound and changing the surface at every point it passed through. Following the passage of the wave, the enormous energy held back by frictional forces begins to be released
The phenomenon of friction exists in almost every action we do in our daily lives - when we pass our hands on a table, open a door with a creaking hinge, when we brake a car and when we start engines. Above all, the phenomenon of friction is particularly relevant to explain the occurrence of earthquakes. Despite the centrality of the phenomenon in our lives, the basic principles of friction processes have been a mystery until now. A new study conducted by physicists at the Hebrew University and recently published in the journal Nature offers a new explanation of the friction process and has implications for the basic understanding of earthquakes and even the possibility of predicting them in the future. A discussion of the research was even published this month in the journal Physics Nature.
The research was carried out by Prof. J. Finberg and research students Oded Ben-David and Shmuel Rubinstein from the Rakah Institute of Physics at the Hebrew University. The researchers found that the friction begins with a kind of wave that passes over the surface that separates the two rubbing bodies. "We created a kind of miniature earthquakes in the laboratory which allowed us to understand the process" explains Prof. Finberg.
Earthquakes occur as a result of frictional movement between the tectonic plates that make up the Earth's crust. The vibration occurs when the forces that move the plates overcome the frictional forces that fix the plates together. The research showed that the release of frictional forces begins with a wave moving at the speed of sound and changing the surface at every point it passed through. Following the passage of the wave, the enormous energy held back by frictional forces begins to be released. The movement of the earth caused by this release is the earthquakes we feel. In addition to this, the study described for the first time how each point of contact loosens its "grip" in a complex series of events following the passage of the wave. The process is characterized by four stages: the stage of severing the relationship, the stage of violent rupture, the stage of renewing the relationship and the stage of re-strengthening it.
"Although frictional movement is often perceived as movement over a smooth surface, in practice there is always a microscopic roughness in the contact surface, and the actual contact points are very few. The nature of the behavior of these points is responsible for the frictional movement" explains Prof. Finberg. In their study, the researchers found that these contact points have a "life of their own" that dictates the development of the friction process.
The research may contribute to understanding a wide range of man-made friction phenomena and natural phenomena such as earthquakes. "Although friction plays an important role in a variety of areas in our lives, it is surprising that key processes related to the movement of friction have not been deciphered so far," says Prof. Finberg. "The current study is an important step in understanding the issue. In nature, earthquakes begin their lives at a depth ranging from 10 to 100 km below the surface. In the research, we were able for the first time to observe the processes that give rise to an earthquake while they are taking place within the framework of the experiment in the laboratory. I hope that a basic understanding of these processes will allow us to predict earthquakes in the future and perhaps even partially prevent the great damage they cause."
On the same topic on the science website
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Another topic that I still haven't been able to understand is what the lateral force is
Separates, rams or moves tectonic plates?
From my personal experience in the 1994 Los Angeles earthquake (6.7 Richter in depth
17 km) and the aftershocks that came after it - they did not have a uniform speed.
I lived about 7 kilometers from the "Epi-Center" and the first earthquake was indeed
The waves (up and down) came at a tremendous speed, but the aftershocks followed
In other words, at different speeds.
I clearly remember one instance where I was standing in line at a gas station (I was outside
to the car) and suddenly an aftermarket arrived around 5 Richter. It was like standing
On a plot over waves of 15 cm that moved around 30 km/h (according to my estimates
the subjective), but clearly not at the speed of sound.
It is not clear to me if as you move away from the center do the waves slow down or their frequency
going down or both.
Another issue that is not clear to me is how earthquakes happen in the center of the plates
The tectonics, there is no meeting/seam there, so how are they formed?
sympathetic:
I read and understood what is written here and in my opinion it is not written enough.
It seems to me that what is written here was mostly self-evident
A. Ben-Ner:
This is not a new idea
http://www.tulane.edu/~sanelson/geol204/eqprediction&cntrl.htm
But one of the problems is where to make the explosions.
As explained here, it is a collection of friction points that you don't know where they are (except for the fact that most of them are very deep).
A hypothetical thought exercise
The shearing forces acting between the tectonic plates are getting stronger over time, however, as explained in the article, there are frictional forces acting between the plates, which prevent relative displacement of the plates. All this until the moment that the shearing forces overcome the friction grip. Then a strong shock wave occurs, the shock wave weakens the frictional forces between the plates and a series of ground movements begins. The idea I propose here is to release the energy stored between the plates, by underground explosions along the connection line between the plates. These explosions will cause a weak earthquake at a much earlier stage before the occurrence of the "natural" earthquake.
True, it's probably not that simple and expensive but…. So is the earthquake damage.
Who is God?
The research described comes to answer several questions, one of which is how the whole body knows that it must move when a force is applied to one side of the body. Apparently, we would expect that the beginning of the movement would be gradual, but it happens almost simultaneously. The innovation in the research is an explanation of the phenomenon. The research shows that the movement of the body is preceded by a precursor wave (moving at the speed of sound). The preliminary wave frees the body, that is, destroys the connection points between the body and the surface, thus allowing the force to move the body as one piece. Most of the energy is then released, which happens in a similar way in earthquakes. If I'm not mistaken, the phenomenon (pre-wave) was known for earthquakes, but the study in question linked this known phenomenon to friction. The greatness of the research is that it links a number of fields that until now were considered independent: friction, crack progression and earthquakes.
Yuhai:
I too can speculate, but I expect an article that will spare me the speculation and present the results of the research in a way that does not imply two or more faces and properly separates what was known before the research and what the research itself discovered.
Machel
Apparently it is about the coordinated cooperation that spreads to all points of friction.
and the transition process from static to dynamic friction and back.
It is not entirely clear what the specific innovation of the study is.
Among other things, it is written in the article that "the research showed that the release of frictional forces begins with a wave moving at the speed of sound and changing the surface at every point where it passed."
This is not something that the research showed for the first time because it has been known for a long time and you can read it here:
http://en.wikipedia.org/wiki/Seismic_wave
I do not assume that there are other things in the research - those that were not known before and related to the "lives of their own" of the contact points, but the problem is mine, at least those things are not known even after reading the article.
Another note, atoms do not unite in the core of the sun because there are no atoms there, there is hot plasma and the nuclei of the atoms unite. An atom is a nucleus with its electrons and has no electric charge (there are no atoms in the sun, there is ionized plasma).
Refresh: Contact between materials happens when the electric forces of repulsion exerted by the electrons and protons in one material on the other material and vice versa are very strong.
refreshed
Equally you might ask why you don't fall into the floor or why your body doesn't disintegrate? For there to be forces there is no need for contact. Chemical bonds between atoms are formed without direct contact, repulsion between charges occurs without contact and the earth attracts bodies to it without contact and countless other examples. What quantum theory teaches us is that forces are transferred by exchanging virtual particles but this point is certainly not relevant to the article presented here.
How is contact or friction between things even possible? After all, at the quantum level atoms never touch each other (unless they are under enormous pressure like in the core of the sun for example, then the atoms touch each other and combine and thus form another substance.