1 point - The earthquake is not felt. Soil vibrations are recorded by instruments.

2 points - An earthquake is felt by very sensitive people who are in complete peace.

3 points - Hanging lamps, indoor flowers, curtains, open doors, stationary cars sway slightly.

4 points - Hanging objects and stationary vehicles sway slightly, liquid in vessels vibrates. There is a faint clink of tightly packed, unstable dishes. An earthquake is felt by most people inside buildings. On rare occasions, people wake up. In the open air, the earthquake is felt by individuals.

5 points - Hanging objects sway noticeably. In rare cases, the pendulums of wall clocks stop. Liquid sometimes splashes out of filled vessels. Unstable dishes and decorations placed on shelves topple over. The earthquake is felt by everyone inside buildings and most outdoors; people wake up, animals are worried.

6 points - Hanging objects sway. Sometimes paintings fall off the shelves and get moved. The pendulums of many wall clocks stop. Light furniture moves. Dishes fall. Many people are running out of the premises, the movement of people is unstable. Animals run out of their shelters.

7 points - Hanging lamps sway violently. Light furniture moves. Books, dishes, vases fall. Everyone runs out of the premises and, in some cases, jumps out of the windows. It is difficult to move without support.

8 points - Some of the hanging lamps are damaged. Furniture moves and topples. Light objects bounce and topple over. People have difficulty staying on their feet.

9 points - Furniture tips over and breaks. Great concern for animals.

10 points - Numerous damage to household items. Animals rush and scream. Tree branches and trunks break.

11 points - Loss of property under the rubble of buildings.

12 points - A severe disaster with casualties. Vegetation and animals die from landslides and landslides in mountainous areas.

- classification of earthquakes by magnitude, based on an assessment of the energy of seismic waves occurring during earthquakes. The scale was proposed in 1935 by the American seismologist Charles Richter (1900‑1985), theoretically substantiated together with the American seismologist Beno Gutenberg in 1941‑1945, and became widespread throughout the world.

The Richter scale characterizes the amount of energy that is released during an earthquake. Although the magnitude scale is not limited in principle, there are physical limits to the amount of energy released in the earth's crust.
The scale uses a logarithmic scale, so that each integer value on the scale indicates an earthquake ten times larger in magnitude than the previous one.

An earthquake with a magnitude of 6.0 on the Richter scale will produce 10 times more ground shaking than an earthquake with a magnitude of 5.0 on the same scale. The magnitude of an earthquake and its total energy are not the same thing. The energy released at the source of an earthquake increases by about 30 times with an increase in magnitude by one unit.
The magnitude of an earthquake is a dimensionless quantity proportional to the logarithm of the ratio of the maximum amplitudes of a certain type of waves of a given earthquake, measured by a seismograph, and some standard earthquake.
There are differences in methods for determining the magnitudes of nearby, distant, shallow (shallow) and deep earthquakes. Magnitudes determined from different types of waves differ in magnitude.

Earthquakes of different magnitudes (on the Richter scale) manifest themselves as follows:
2.0 - the weakest felt shocks;
4.5 - the weakest shocks, leading to minor damage;
6.0 - moderate damage;
8.5 - the strongest known earthquakes.

Scientists believe that earthquakes stronger than magnitude 9.0 cannot occur on Earth. It is known that each earthquake is a shock or a series of shocks that arise as a result of the displacement of rock masses along a fault. Calculations have shown that the size of the earthquake source (that is, the size of the area on which the rocks were displaced, which determines the strength of the earthquake and its energy) with weak tremors barely perceptible by humans is measured in length and vertically by several meters.

During earthquakes of medium strength, when cracks appear in stone buildings, the size of the source reaches kilometers. The sources of the most powerful, catastrophic earthquakes have a length of 500-1000 kilometers and go to a depth of up to 50 kilometers. The largest earthquake recorded on Earth has a focal area of ​​1000 x 100 kilometers, i.e. close to the maximum length of faults known to scientists. A further increase in the depth of the source is also impossible, since earthly matter at depths of more than 100 kilometers goes into a state close to melting.

Magnitude characterizes an earthquake as a single, global event and is not an indicator of the intensity of the earthquake felt at a specific point on the Earth's surface. The intensity or strength of an earthquake, measured in points, not only strongly depends on the distance to the source; Depending on the depth of the center and the type of rock, the strength of earthquakes with the same magnitude can differ by 2-3 points.

The intensity scale (not the Richter scale) characterizes the intensity of the earthquake (the effect of its impact on the surface), i.e. measures the damage caused to a given area. The score is established when examining the area based on the magnitude of destruction of ground structures or deformations of the earth's surface.

There are a large number of seismic scales, which can be reduced to three main groups. In Russia, the 12-point scale MSK-64 (Medvedev-Sponheuer-Karnik), which is the most widely used in the world, is used, dating back to the Mercalli-Cancani scale (1902), in Latin American countries the 10-point Rossi-Forel scale (1883) is adopted, in Japan - 7-point scale.

More than 2000 years ago, a device was created in China to warn people against an upcoming earthquake. This device was shaped like a frog, with an oval base and four inclined planes in which metal balls were placed. When an earthquake occurred, vibrations caused by seismic waves rocked the device and the balls fell out of their nests onto a metal stand. It was a warning of an approaching earthquake. Thus, from the first days of the emergence of the science of seismology, its task was to warn people about an approaching earthquake, thereby ensuring the safety of people’s lives from natural disasters. It took 2000 years for the infamous decision of an international conference in London in 1996 to appear, which stated that earthquake prediction was not possible. Does this mean that the efforts of thousands of scientists who dedicated their lives to solving this problem of humanity and billions of dollars spent on research were in vain? The fact that this decision was made by “skeptics,” as scientists are called who have lost hope of finding a positive result in the study of a specific problem, out of despair, was clear even then, because since June 1995 The press in more than 20 countries reported that the Sakhalin earthquake was predicted by the author and the Russian Emergency Situations Ministry received a warning from the Armenian Emergency Situations Ministry three months before the tragedy, when the city of Neftegorsk disappeared from the face of the Earth. At the beginning of the twentieth century, changes in the ratio of longitudinal (VP) and transverse (VS) seismic waves in the zone of development of the source of strong earthquakes were first obtained. And this attitude became the first harbinger of earthquakes. Scientists in many developed countries of the world have begun to conduct research with the goal of creating earthquake forecasting technology capable of determining the location (latitude and longitude coordinates of the source), time (year, month, day) and strength (magnitude) of future earthquakes. Currently, more than 300 earthquake precursors are known, which have not led to a solution to this problem and the question of earthquake prediction remained unanswered. What is the reason for the failure? Due to the catastrophic consequences that lead to a huge number of casualties and destruction, earthquakes are the most dangerous natural disasters. The number of victims from earthquakes in the twentieth century was 1.4 million (Osipov, 2001), of which about 1.0 million victims occurred in the last 30 years. In the first 12 years of the 21st century, the number of deaths from earthquakes is approaching 1.0 million (about 800,000): Indonesia (about. Sumatra, 2004) - about 300,000; Haiti – about 300,000; Japan (Fukushima)…The following occur annually: 1 earthquake – with a magnitude of up to 9; about 15 earthquakes - up to 8; 140 - up to 7; 900 - up to 6; 8000 - up to 5. Currently, these numbers tend to increase. Scientists from all over the world have been and are studying the issue of predicting earthquakes, and billions of dollars have been spent on this research, but earthquakes continue to destroy cities, people, and countries. What is the reason for the helplessness of scientists from all over the world? Politicians and the Ministry of Emergency Situations are not interested in these issues, but Governments turn to them when a disaster occurs and people, cities and countries die. At the London conference in 1996. Many experts have concluded that seismic forecasting is hopeless. The results of the conference were published: “Is seismic forecasting hopeless? Complete pessimism regarding the possibility of reliable earthquake prediction was expressed by some geophysicists at an international conference held in November 1996 in London. R. Geller (University of Tokyo) noted that, despite the efforts and resources expended by the international community of scientists, over the past decades it has not been possible to detect a single reliable sign of an impending seismic event (some signals are at the noise level or even below, undue importance has been given). Seismologist S. Crampin (University of Edinburgh, Scotland) shared this opinion. Experts' skepticism increased after several Greek seismologists announced that they were allegedly able to predict earthquakes based on previous variations in the Earth's magnetic field; The decisive criticism of their report pointed to completely vague information about the place and time of the upcoming tremors and their intensity. Many scientists now believe that earthquakes are generally among the critical phenomena that occur in a system brought to the brink of unstable equilibrium. Predicting specifically when a critical event will occur is almost impossible; According to seismologist I.Main (I.Main; University of Edinburgh), predicting an earthquake is as difficult as determining in advance which particular snowflake will cause an avalanche in the mountains. However, having classified tremors as a critical phenomenon, experts can now make new amendments to building codes taking into account scientific criteria for the seismic resistance of structures (existing rules are mainly based on bare empirics). New Scientist. 1996.V.152. N 2056. P.10 (Great Britain).” So, in 1996 An international conference in London, based on the opinion of R. Geller (University of Tokyo) and two employees of the University of Edinburgh, pronounced a verdict on more than a century of work by world scientists on the impossibility of determining in advance the place, time and magnitude of a future earthquake. Apparently the authors of this project were not aware that in 1995, i.e. one year before the London decision, the author of these lines developed a physical model that allows theoretical calculation of the parameters of future earthquakes on the planet: location (latitude and longitude coordinates), time (year, month and day) and strength (magnitude) for an unlimited time forward - a methodology for short-term forecasting of earthquakes and other natural disasters (Publications: 1. Forecasting earthquakes. Monograph. Increasing the seismic resistance of buildings and structures. Publishing house "Hayastan", Yerevan, 1989, chapter, 8.5, p. 316. 2. Electromagnetic model of the mechanism of occurrence source of earthquakes. "Bulletin" of the International Academy of Sciences of Ecology and Life Safety, St. Petersburg, No. 7(19), 2000, 3. Pattern of connection of seismic waves emitted by the source of earthquakes. "Bulletin" of the International Academy of Sciences of Ecology and Life Safety, St. St. Petersburg, No. 7(31), 2000 4. Short-term forecast of earthquakes and other natural disasters. Monograph. St. Petersburg, 2000, p. 135. 5. Earthquakes and natural disasters shorth-term prediction. St. Petersburg. 2000, p. 128). Moscow, Russia; "Shukan Shincho", 07/07/1995, Tokyo, Japan; BBC, 1995, London, Great Britain; Turkey, "Marmara" 1995; Iran, "Alik" 1995; USA ... more than 20 countries). Over the past 17 years, this method has been used to calculate the parameters (location, time and magnitude) of more than 40,000 future earthquakes and other natural disasters, with an accuracy of up to 95%, including all disasters that occurred during this time. Short-term forecast of earthquakes using instrumental, and Moreover, the probabilistic research methods used by modern seismology are really not possible. Therefore, until now, all efforts of scientists in this area of ​​seismology have failed. How do studies conducted today differ from those used in 1996? ? Nothing, only the quantity and, possibly, quality of the equipment used has increased. Therefore, one cannot count on success in solving the problem of short-term earthquake forecasting using “modern methods of instrumental research”. In this matter, the London Conference would have been more useful if the decision adopted at it had added; "modern methods of instrumental research." Short-term forecasting of earthquakes and other natural disasters is possible and exists. It is possible to predict future natural disasters with absolute accuracy for an unlimited time in advance. The method consists of two parts. 1. A theoretical calculation of the location, time and strength of future earthquakes is carried out... 2. A month before the calculated time, seismic stations of a given country conduct studies of changes in parameters of the specified region and clarify the theoretical calculation. This will allow, 3-4 days before the earthquake, to accurately indicate the location, time and strength of the future earthquake. 3. Accurate data obtained about a future earthquake, tsunami... are transferred to the Government, which will make a decision on the safety of people’s lives.

Seismic scale

Earthquakes- tremors and vibrations of the Earth's surface caused by natural causes (mainly tectonic processes) or artificial processes (explosions, filling of reservoirs, collapse of underground cavities in mine workings). Small tremors can also cause lava to rise during volcanic eruptions.

About a million earthquakes occur throughout the Earth each year, but most are so small that they go unnoticed. Really strong earthquakes, capable of causing widespread destruction, occur on the planet about once every two weeks. Fortunately, most of them occur on the bottom of the oceans, and therefore are not accompanied by catastrophic consequences (if an earthquake under the ocean does not occur without a tsunami).

Earthquakes are best known for the devastation they can cause. Destructions of buildings and structures are caused by soil vibrations or giant tidal waves (tsunamis) that occur during seismic displacements on the seabed.

Introduction

The cause of an earthquake is the rapid displacement of a section of the earth's crust as a whole at the moment of plastic (brittle) deformation of elastically stressed rocks at the source of the earthquake. Most earthquakes occur near the Earth's surface. The displacement itself occurs under the action of elastic forces during the discharge process - a decrease in elastic deformations in the volume of the entire section of the slab and a displacement to the equilibrium position. An earthquake is a rapid (on a geological scale) transition of potential energy accumulated in elastically deformed (compressed, sheared or stretched) rocks of the earth's interior into the energy of vibrations of these rocks (seismic waves), into the energy of changes in the structure of rocks at the source of the earthquake. This transition occurs when the tensile strength of the rocks at the source of the earthquake is exceeded.

The tensile strength of crustal rocks is exceeded as a result of an increase in the sum of forces acting on it:

1. Forces of viscous friction of mantle convection flows on the earth's crust;
2. Archimedean force acting on the light crust from the heavier plastic mantle;
3. Lunar-solar tides;
4. Changing atmospheric pressure.

These same forces also lead to an increase in the potential energy of elastic deformation of rocks as a result of displacement of plates under their action. The potential energy density of elastic deformations under the influence of the listed forces increases in almost the entire volume of the slab (in different ways at different points). At the moment of an earthquake, the potential energy of elastic deformation in the earthquake source quickly (almost instantly) decreases to the minimum residual energy (almost to zero). Whereas in the vicinity of the source, due to the displacement of the plate as a whole during an earthquake, elastic deformations increase somewhat. That is why repeated earthquakes - aftershocks - often occur in the vicinity of the main earthquake. In the same way, small “preliminary” earthquakes - foreshocks - can provoke a large one in the vicinity of the initial small earthquake. A large earthquake (with large plate displacement) can cause subsequent induced earthquakes even at distant plate edges.

Of the listed forces, the first two are much larger than the 3rd and 4th, but their rate of change is much less than the rate of change of tidal and atmospheric forces. Therefore, the exact time of arrival of an earthquake (year, day, minute) is determined by changes in atmospheric pressure and tidal forces. Whereas much larger, but slowly changing forces of viscous friction and Archimedean force set the time of arrival of an earthquake (with a focus at a given point) with an accuracy of centuries and millennia.

Deep-focus earthquakes, the foci of which are located at depths of up to 700 km from the surface, occur at convergent boundaries of lithospheric plates and are associated with subduction.

Seismic waves and their measurement

Types of seismic waves

Seismic waves are divided into compression waves And shear waves.

• Compression waves, or longitudinal seismic waves, cause vibrations of the rock particles through which they pass along the direction of wave propagation, causing alternating areas of compression and rarefaction in the rocks. The speed of propagation of compression waves is 1.7 times greater than the speed of shear waves, so seismic stations are the first to record them. Compression waves are also called primary(P-waves). The speed of the P-wave is equal to the speed of sound in the corresponding rock. At frequencies of P-waves greater than 15 Hz, these waves can be perceived by ear as an underground hum and rumble.
• Shear waves, or seismic transverse waves, cause rock particles to vibrate perpendicular to the direction of propagation of the wave. Shear waves are also called secondary(S-waves).

There is a third type of elastic waves - long or superficial waves (L-waves). They are the ones who cause the most destruction.

Measuring the strength and impacts of earthquakes

A magnitude scale and an intensity scale are used to evaluate and compare earthquakes.

Magnitude scale

The magnitude scale distinguishes earthquakes by magnitude, which is the relative energy characteristic of the earthquake. There are several magnitudes and, accordingly, magnitude scales: local magnitude (ML); magnitude determined from surface waves (Ms); body wave magnitude (mb); moment magnitude (Mw).

The most popular scale for estimating earthquake energy is the local Richter magnitude scale. On this scale, an increase in magnitude by one corresponds to a 32-fold increase in the released seismic energy. An earthquake with a magnitude of 2 is barely noticeable, while a magnitude of 7 corresponds to the lower limit of destructive earthquakes covering large areas. The intensity of earthquakes (cannot be assessed by magnitude) is assessed by the damage they cause in populated areas.

Intensity scales

Medvedev-Sponheuer-Karnik scale (MSK-64)

The 12-point Medvedev-Sponheuer-Karnik scale was developed in 1964 and became widespread in Europe and the USSR. Since 1996, the European Union has used the more modern European Macroseismic Scale (EMS). MSK-64 is the basis of SNiP-11-7-81 “Construction in seismic areas” and continues to be used in Russia and the CIS countries.

Point	Earthquake strength	a brief description of
1	Not felt.	Marked only by seismic instruments.
2	Very weak tremors	Marked by seismic instruments. It is felt only by certain people who are in a state of complete peace in the upper floors of buildings, and by very sensitive pets.
3	Weak	It is felt only inside some buildings, like a shock from a truck.
4	Moderate	Recognized by slight rattling and vibration of objects, dishes and window glass, creaking of doors and walls. Inside the building, most people feel the shaking.
5	Quite strong	In the open air it is felt by many, inside houses - by everyone. General shaking of the building, vibration of furniture. The clock pendulums stop. Cracks in window glass and plaster. Awakening the Sleepers. It can be felt by people outside buildings; thin tree branches are swaying. Doors slam.
6	Strong	It is felt by everyone. Many people run out into the street in fear. Pictures fall from the walls. Individual pieces of plaster are breaking off.
7	Very strong	Damage (cracks) in the walls of stone houses. Anti-seismic, as well as wooden and wicker buildings remain unharmed.
8	Destructive	Cracks on steep slopes and wet soil. Monuments move out of place or topple over. Houses are heavily damaged.
9	Devastating	Severe damage and destruction of stone houses. Old wooden houses are crooked.
10	Destructive	Cracks in the soil are sometimes up to a meter wide. Landslides and collapses from slopes. Destruction of stone buildings. Curvature of railway rails.
11	Catastrophe	Wide cracks in the surface layers of the earth. Numerous landslides and collapses. Stone houses are almost completely destroyed. Severe bending and bulging of railway rails.
12	Major disaster	Changes in the soil reach enormous proportions. Numerous cracks, collapses, landslides. The appearance of waterfalls, dams on lakes, deviation of river flows. Not a single structure can withstand.

What happens during strong earthquakes

An earthquake begins with the rupture and movement of rocks at some place deep in the Earth. This location is called the earthquake focus or hypocenter. Its depth is usually no more than 100 km, but sometimes it reaches 700 km. Sometimes the source of an earthquake can be near the surface of the Earth. In such cases, if the earthquake is strong, bridges, roads, houses and other structures are torn and destroyed.

The area of ​​land within which on the surface, above the source, the force of tremors reaches its greatest magnitude is called the epicenter.

In some cases, layers of earth located on the sides of a fault move toward each other. In others, the ground on one side of the fault sinks, forming faults. In places where they cross river channels, waterfalls appear. The vaults of underground caves are cracking and collapsing. It happens that after an earthquake large areas of the earth sink and are filled with water. Earth tremors displace the upper, loose layers of soil from the slopes, forming landslides and landslides. During the earthquake in California last year, a deep crack appeared on the surface. It stretches for 450 kilometers.

It is clear that the sudden movement of large masses of earth in the source must be accompanied by a blow of colossal force. Over the year people [ Who?] can feel about 10,000 earthquakes. Of these, approximately 100 are destructive.

Measuring instruments

To detect and record all types of seismic waves, special instruments are used - seismographs. In most cases, the seismograph has a weight with a spring attachment, which during an earthquake remains motionless, while the rest of the device (body, support) begins to move and shifts relative to the load. Some seismographs are sensitive to horizontal movements, others to vertical ones. The waves are recorded by a vibrating pen on a moving paper tape. There are also electronic seismographs (without paper tape).

Other types of earthquakes

Volcanic earthquakes

Volcanic earthquakes are a type of earthquake in which an earthquake occurs as a result of high tension in the interior of a volcano. The cause of such earthquakes is lava, volcanic gas. Earthquakes of this type are weak, but continue for a long time, many times - weeks and months. However, an earthquake does not pose a danger to people of this type.

Man-made earthquakes

Recently, information has emerged that earthquakes can be caused by human activity. For example, in areas of flooding during the construction of large reservoirs, tectonic activity increases - the frequency of earthquakes and their magnitude increases. This is due to the fact that the mass of water accumulated in reservoirs increases the pressure in rocks with its weight, and seeping water reduces the tensile strength of rocks. Similar phenomena occur when large quantities of rock are removed from mines, quarries, and during the construction of large cities from imported materials.

Landslide earthquakes

Earthquakes can also be caused by landslides and large landslides. Such earthquakes are called landslides; they are local in nature and have low strength.

Earthquakes of artificial nature

An earthquake can also be caused artificially: for example, by the explosion of a large amount of explosives or during a nuclear explosion. Such earthquakes depend on the amount of material exploded. For example, during the DPRK's testing of a nuclear bomb, a moderate earthquake occurred in 2016, which was recorded in many countries.

The most destructive earthquakes

• January 23 - Gansu and Shaanxi, China - 830,000 deaths
• - Jamaica - Turned into ruins in Port Royal
• - Kolkata, India - 300,000 people died
• - Lisbon - from 60,000 to 100,000 people died, the city was completely destroyed
• - Colabria, Italy - between 30,000 and 60,000 people died
• - New Madrid, Missouri, USA - the city has been reduced to ruins, flooding over an area of ​​500 sq. km
• - Sanriku, Japan - the epicenter was under the sea. A giant wave washed away 27,000 people and 10,600 buildings into the sea
• - Assam, India - Over an area of ​​23,000 sq. km, the relief is changed beyond recognition, probably the largest earthquake in the history of mankind
• - San Francisco, USA 1,500 people died, 10 sq. km destroyed. cities
• - Sicily, Italy 83,000 people died, the city of Messina was reduced to ruins
• - Gansu, China 20,000 people died
• - Great Kanto earthquake - Tokyo and Yokohama, Japan (8.3 Richter) - 143,000 people died, about a million were left homeless as a result of the resulting fires
• - Inner Taurus, Türkiye 32,000 people died
• - Ashgabat, Turkmenistan, Ashgabat earthquake, - 110,000 people died
• - Ecuador 10,000 people died
• - The Himalayas cover an area of ​​20,000 sq. km in the mountains.
• - Agadir, Morocco 12,000 - 15,000 people died
• - Chile, about 10,000 killed, cities of Concepcien, Valdivia, Puerto Mon destroyed
• - Skopje, Yugoslavia about 2,000 killed, most of the city reduced to ruins
• - Anchorage, Alaska, USA, most of the city was turned into ruins, large landslides, 300 km of railway were destroyed

Earthquakes vary in strength and impact on the earth's surface. And science has repeatedly attempted to classify them according to these indicators.

As a result of such attempts, 12-point scales were developed, based on an assessment of their impact on the earth's surface.

12-point scale for assessing the intensity of earthquakes (hereinafter earthquake scale) estimates the intensity of an earthquake in points at a given point, regardless of its power at the epicenter.

Richter scale has a different approach and estimates the amount of seismic energy released at the epicenter of an earthquake. The unit of seismic energy is magnitude.

12 point earthquake scale.

In 1883, 12 ball earthquake scale was designed by Giuseppe Mercali. Later it was improved by the author himself, and subsequently also by Charles Richter (the author of the Richter scale) and was called the Modified Mercalli Earthquake Scale.

This earthquake scale is currently used in the United States.

In the USSR and Europe, the 12-point earthquake scale - MSK-64 - was used for a long time. According to it, as well as the Mercalli earthquake scale, their intensity is measured in points indicating the intensity, nature and scale of the impact on the surface of the earth, buildings, people and animals in a given area.

The MSK-64 earthquake scale is very clear. And if we hear in the media that an earthquake with a magnitude of 6 occurred, we can very easily imagine that, according to this earthquake scale, it was strong and was felt by all people. Many of them ran out into the street. Pieces of plaster fell off and paintings fell from the walls.

Or a 9.0 magnitude earthquake can be imagined as devastating, in which stone houses were damaged and destroyed, and wooden houses were knocked down.

Everything is simple and clear.

It should be noted that according to the earthquake scale, their intensity is assessed at a certain point. It is clear that at the epicenter located above the source of the earthquake and at a distant point its intensity will be different.

In 1988, the European Seismic Committee began updating the MSK-64 earthquake scale and in 1996, an updated earthquake scale called EMS-98, along with a manual for use, was recommended for use. This earthquake scale is also 12 point and has no fundamental differences with other earthquake scales.

In Japan, the earthquake scale of the Japan Meteorological Agency is used. It starts at three points when people begin to feel the points.

It describes in separate columns the impact on people, on the environment inside buildings and on the street. The highest rating on this earthquake scale is 7.

It is also not fundamentally different from other scales.

Richter scale. Magnitude.

Often, including in the media, you can hear about an earthquake occurring somewhere with a force of, for example, 6 points on the Richter scale.

This is not true. The Richter scale does not describe the intensity of an earthquake, expressed in points, but a completely different characteristic, expressed in other units.

The Richter scale estimates the amount of released seismic energy at the epicenter based on the amplitude of soil vibrations measured by instruments that reached the measurement point. This value is expressed in magnitude.

Richter himself defined the magnitude of any shock as: “the logarithm, expressed in microns, of the amplitude of the recording of this shock made by a standard short-period twisting seismometer at a distance of 100 kilometers from the epicenter.”

Magnitude calculated after measuring the amplitude on the seismogram. And when making calculations, it is necessary to make corrections: for the depth of the earthquake source, for the fact that the measurements were carried out with a non-standard seismometer. It is necessary to bring the calculations to those measured at a standard distance of 100 km from the epicenter.

This is not an easy calculation. And due to the listed difficulties, magnitude values ​​​​produced by different sources may differ slightly.

But in general, they will give an objective assessment of the power of the earthquake.

Therefore, it would be correct to say that an earthquake with a magnitude of, say, -5 on the Richter scale occurred in a certain place.

Magnitude, calculated at different points on the Richter scale will have the same value. The intensity of the shocks in points at different points will be different.

This is the difference between the 12-point earthquake scale and the 9.5-point Richter scale, expressed in magnitude (the Richter scale has a range of 1 - 9.5 magnitude).

You should not confuse (and this happens all the time in the media) the concepts of the Richter scale and the 12-point earthquake scale.

The intensity on the Richter scale is determined immediately from the readings of seismographs. The intensity in points is determined later, based on an assessment of the impact on the earth's surface. Therefore, the very first reports on assessing the power of shocks come precisely on the Richter scale.

How to correctly report the intensity of tremors in magnitude on the Richter scale?

The correct usage is “an earthquake of magnitude 7 on the Richter scale.”

Previously, due to an oversight, the incorrect expression was used - “an earthquake of 7 points on the Richter scale.”

Or it’s also incorrect - “an earthquake of magnitude 7 on the Richter scale” or “magnitude 7 on the Richter scale.”

The Richter scale describes the power of tremors at the epicenter, regardless of conditions, and introduces a unit of measurement for the power of tremors - magnitude. Other scales describe their impact on the surface in different places depending on conditions, soils, rocks, distance from the epicenter, etc.

For this reason Richter scale is the most objective and scientifically based.

Richter scale(joke)