The Richter scale - what is its practical use?

Each of us has heard about the dangers that an earthquake brings to life and health of people. Fortunately, modern seismic devices are able to predict the possible onset of an earthquake, and the authorities have the opportunity to notify the population of the imminent threat, and in some cases evacuate it from the area of the expected disaster. But how to understand how strong the tremors will be, and what harm will they do? After all, the earthquake has a hypocenter (a focus in the thickness of the earth's crust), an epicenter (a point on the surface of the earth beneath which the hypocenter is located), in addition, the earthquake's destructiveness is affected by soil composition and even seismic stability of buildings. In some cases, the tremors may be felt weaker, and in some cases stronger. Now, to measure the strength of soil vibrations, the international Richter scale has been adopted, and the magnitude of the seismic shock has been recognized as a magnitude.

For the sake of justice, it should be noted that it is not Richter who owns the laurels of the development of an international earthquake intensity scale. It was developed by the Italian scientist Merkalli, and until the 30-ies of the twentieth century it was called - "the scale of the Mercalli." It consisted of 12 points (most likely, by analogy with the estimated speed and wind force 12-point Beaufort scale). According to Mercalli, the weakest impetus (intensity of 1 point) is felt only by individuals who are sensitive to earthquakes, and the strongest (12 points) leads to complete destruction of buildings and even changes in the landscape. On the Mercalli scale, earthquakes above 6 points were considered strong, and below - weak. But the Mercalli scale, not all countries used: for example, in Japan it was accepted to measure earthquakes at a 7-point school, and in some countries they used the 10-point scale of Rossi and Forel. With the onset of globalization, it became necessary to develop an international scale, so that seismographs from around the world could clearly and clearly explain the extent of the imminent threat to their neighbors. Such a scale, which has become universally accepted throughout the world, has become the Richter scale.

At first, the Japanese scientist T. Valati proposed to enter the logarithmic scale of magnitudes (in translation from Latin magnitudo - size, magnitude) for earthquake force measurement, which take into account the total energy of earth's oscillations. American seismograph C. Richter proposed to use the decimal logarithm of the greatest amplitude of soil oscillations (which is calculated directly in proportion to the deviation of the needle on the seismograph, making an adjustment for the distance from the epicenter) to measure earthquake magnitude. This scientific explanation does not allow, of course, the common man to correctly judge how the Richter scale will help him to determine the risks in the coming earthquake.

In Russia, earthquakes that record only seismic instruments, but not people, are estimated at 1 point. If the dishes are jarring in the cupboard, and chandeliers are shaking on the upper floors of the high-rise buildings , then the earthquake is estimated at 4 points. Of course, this is only observation of the territory, which can be removed from the epicenter by many hundreds of kilometers, and the Richter scale with these points coincides extremely rarely. But nevertheless, such a Russian characteristic of the force of jerks has that practical advantage that it allows us to work out the correct actions for an earthquake. So, with a thrust intensity of 6 points, you must leave the room (especially the panel and high), and if this is impossible, stay away from the windows and closer to the inner walls of the building.

By the way, despite the fact that Richter broke his scale by 12 points, the strongest earthquake that was observed with the help of instruments never exceeded the magnitude of 9 points. It was a devastating earthquake that occurred in north-eastern India on August 15, 1950. It brought death to 1,500 people, but after it on the ground new faults and failures were formed, and the river Brahmaputra changed its course.