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Research earthquake: Researchers from the Hebrew University offer a way to predict the severity of earthquakes

The research, recently published in the journals Science and Wired, revealed that the forces exerted on the points of contact between the surfaces can be stronger, up to five times more than predicted by the coefficient of friction, before the contacts between them break and the upper surface begins to slide

Interstate 880 Oakland, California, after the 1989 earthquake. From Wikipedia
Interstate 880 Oakland, California, after the 1989 earthquake. From Wikipedia

Researchers from the Hebrew University succeeded in a laboratory experiment in undermining the common perception in physics regarding the processes that occur during an earthquake. The research findings have far-reaching implications for understanding the earthquake process and in the future the findings may make it possible to predict severe earthquakes ahead of time.

The researchers - Prof. J. Feinberg Dr. Gil Cohen and research student Oded Ben-David from the Rakah Institute of Physics at the Hebrew University - conducted an experiment in their laboratory that simulated the occurrence of a small earthquake and through it demonstrated how assumptions that had been accepted in the field of physics for hundreds of years, including laws that were first described on Leonardo da Vinci's hands in the 15th century are not valid for the description of earthquakes. "For hundreds of years, physicists have believed that the amount of force needed, for example, to make a book slide on a table is determined by the "coefficient of friction" - a number that expresses the ratio of forces between two surfaces that slide on top of each other," explains the editor of the study Prof. Finberg. "We discovered that these laws are not relevant when trying to apply them to predict the movement of contact points located along the two surfaces."

In the experiment, the researchers pressed two surfaces towards each other and checked what happens at the exact moment when they start to slide on top of each other. Using sensitive sensors, the researchers measured the effort exerted on the surfaces and by combining a system of lasers and a high-speed camera followed the points of friction between the surfaces. Although to the naked eye it appears that the surfaces touch each other along all the points of contact between them, in fact contact surfaces are always rough and real contact between them occurs only at relatively few microscopic contact points.

The research, recently published in the journals Science and Wired, revealed that the forces exerted on the points of contact between the surfaces can be stronger, up to five times more than predicted by the coefficient of friction, before the contacts between them break and the upper surface begins to slide.

According to Prof. Feinberg, the results of the experiment simulate in a small way what happens in an earthquake in reality. "Breaking the contacts between the surfaces in the laboratory simulates the movement of tectonic plates that occurs during an earthquake. In the experiment, we could observe how the earthquake develops and measure all the relevant variables in a way that we would never be able to notice them underground."

The researchers also found that the contact points break through different types of breaking waves. These breaking waves are, in fact, earthquakes. The researchers discovered that earthquakes exist in three fundamentally different states: slow breaking waves that move at a speed much lower than the speed of sound, breaking waves that move at the speed of sound and "super fast" breaking waves that move at a speed higher than the speed of sound. In their study, the researchers discovered that the types of breaking waves are determined by the amount of energy stored along the contact surface of the plates. The speed measured in the laboratory provides a benchmark both for the degree of energy that will be released in an actual earthquake and for the way and rate of its release. For example, slow breaking waves can release energy equivalent to the amount of energy released in the most destructive earthquake - but almost without being felt. On the other hand, ultrasonic breaking waves can be much more destructive than a "normal" vibration.

Although it is not yet possible to make an accurate measurement of the pressures created along the fault between the plates, the current study presents a simulation of the pressures that occur when an earthquake is approaching, and how one earthquake can prepare the conditions for the next. "The findings have many implications in the field of physics as well as the researchers' ability to understand how earthquakes occur, how severe their development may be along the fault line and finally provide an unprecedented predictive capability in assessing the state of the fault and the scope of a future earthquake" Prof. Finberg concludes.

On the same topic on the science website

5 תגובות

  1. Many universities are involved in the development of the iPhone. If it weren't for the scientific research in physics, materials theory, computer science, mathematics and a million and one other fields for many years before the appearance of the iPhone, neither Apple nor any company would have been able to create anything significant.

  2. dear scion,
    You rightly said that science allegedly leaks news to Wired. But according to the agreement that Science signs with the authors of the article, it is not allowed to transmit scientific news to news papers before it has published the article in the journal. But there are stipulations to the agreement with the writers... When is it allowed to transmit scientific news after all? That is, when is it allowed to leak? When the scientists present the new at the conference and when the scientist talks about the new in his blog - a blog is not included in the agreement. Then it is allowed to leak before the article is published in the journal. That is, it is allowed to report from the conference and not from the article itself which has not yet been published. So what do we do? The scientist is going to present Piper at a new conference before the article is published in the journal and leaked to the news papers. But the "leak" is not considered advertising. This is just a news item that appears in science news papers like Wired, Science Direct, New Science and more that usually originates from Piper from the conference. This is a well-known trick and I once published an article about it in one of the well-known newspapers. There is only one place where a professional article can be published and that is a professional scientific journal, such as science.
    And good luck with the PhD, of course. Obviously, no university has created an iPhone 4. Because as soon as you create such a device... she will be a millionaire. In the meantime, the universities are leaking. 🙂

  3. Gali Mami, in the fields where most of the innovation is done in the academy - fields that mainly interest those who participate in the beautiful and geeky - the target audience is a bit limited.... What you wrote is correct.... In almost every field of interest... The things will be published in Wired long before they are (not) published in Science

    I'm not trying to cut. In my fault, I also write a doctorate and more on computers, but you have to recognize the facts...
    No university has yet created an iPhone 4…..

  4. Science is the important journal in which the research is published, while Wired is a popular journal that reports on scientific innovations that appear in Science. That's why research can never be published in Wired. Wired is sort of like the scientist plus minus, a British news report, which also has a YouTube slot where he uploads excellent videos that he produces himself.
    Regarding the earthquake simulation. In reality there are interfering factors. Suppose you understand the mechanism in the laboratory and how severe the earthquake can be, etc. But then when you leave the laboratory to nature, disturbing factors are added to the mechanism that intensify and can be precisely the critical ones. So what do we do then?

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