11 points on the Richter scale is considered. Types of seismic waves. History of the Richter scale

Thanks to modern technologies, scientists managed to calculate how many earthquakes occur annually on our planet. There are more than a million of them. Most of them are not felt by people because of their low magnitude, but there are those that become a real disaster.

What is earthquake magnitude and how is it measured? How do scientists manage to determine which of the phenomena will cause damage, and which will remain imperceptible?

Magnitude

Scientists have developed special scales that measure the strength of tremors. To understand what the magnitude of an earthquake is, it is necessary to familiarize yourself with the magnitudes of the measurements of this phenomenon.

There are several types of scales: Mercalli - Kankani, Medvedev - Sponheuer - Karnik, Richter. Thanks to them, it is clear what magnitude is. It is a number that can be measured against a certain benchmark. During the next earthquake, it is customary to talk about the magnitude and magnitude.

Magnitude scale

For a long time, the Mercalli-Kankani grid was considered the very first scale. Nowadays, it is an outdated model, so the value of tremors is not measured by it.

However, on its basis, all modern methods assessment of the force of blows, including the international scale MSK 64 (Medvedev - Sponheuer - Karnik). It is taken in most countries of the world to analyze the intensity of the phenomenon.

MSK 64

This assessment system is represented by a twelve-point scale. From it you can find out what characterizes the magnitude of an earthquake:

1 point Such phenomena are not felt by people, but they are recorded by devices.
2 points. In some cases, they can be observed by people, most often on the upper floors of buildings.
3 points. Impacts are noticeable to those with high sensitivity.
Earthquake 4 points. There is a rattling of glass.
5 points. It is considered a fairly tangible earthquake, in which individual objects can sway.
6 points. Formation of cracks in buildings.
7 points. Heavy objects may fall. Large cracks appear in the walls of buildings.
8 points. Houses are partially destroyed.
9 points. Buildings and other structures collapse.
10 points. Deep cracks appear in the ground, old buildings are completely destroyed.
11 points. Numerous cracks appear on the surface of the earth, collapses occur in the mountains. Buildings are completely destroyed.
12. The relief is seriously changing, and the buildings are completely destroyed.

Richter score

In 1935, the scientist C. Richter suggested that the magnitude is the energy of seismic waves. Based on this statement, he developed a special scale, according to which concussion activity is still assessed.

The Richter magnitude scale characterizes the amount of energy released during seismic activity. It uses a logarithmic scale, where each value indicates a push ten times the previous one. For example, if a magnitude 4 earthquake is recorded, then the phenomenon will cause ten times a stronger oscillation than a magnitude 3 on the same scale.

According to Richter, seismological activity is measured as follows:

1.0-2.0 - fixed by devices;

2.0-3.0 - weak sensations of shocks;

3.0 - chandeliers swing in houses;

4-5 - shocks are weak, but can cause minor damage;

6.0 - shocks capable of causing moderate destruction;

7 - it is difficult to stand on your feet, cracks begin to go along the walls, flights of stairs can collapse;

8.5 - very strong earthquakes that can cause changes in relief.

9 - causes a tsunami, the soil cracks badly.

10 - the depth of the fault is one hundred or more kilometers.

Earthquakes in history

One of the most strong earthquakes in the world was the seismological activity recorded in 1960 in Chile. On the Richter scale, the instruments indicated significant activity. Then the Chileans learned what a magnitude 8.5 is. The tremors caused a tsunami with a wave height of ten meters.

Four years later, in the northern part of the Gulf of Alaska, shaking of magnitude 9 was recorded. Due to this plate activity, there has been a strong change in the coastline of some of the islands.

Another powerful earthquake occurred in 2004 in the Indian Ocean. It has a score of 9 on the Richter scale. The shocks caused the strongest tsunami with a wave height of more than fifteen meters.

In 2011, an earthquake occurred in Japan, which caused a huge tragedy: thousands of people died and a nuclear power plant was destroyed.

Unfortunately, such disasters are not uncommon. How to prevent earthquakes, scientists do not yet know.

Richter scale was invented to determine the strength of the earth's vibrations. In other words, it will help us determine the magnitude of earthquakes. This system is international. It was invented by the Italian Mercalli. Who was Richter and why did he get all the laurels?

History of the Richter scale

Richter earthquake scale developed in the thirties of the twentieth century. The Mercalli system was not only renamed, but also completed. The Italian took the 12-point scale as the basis. The minimum shocks were equal to one.

Earthquakes from 6 points were considered strong. Not all states agreed with this. , for example, a 10-point scale was used, and in Japan a 7-point scale. But in the age of globalization, everything has changed.

A common standard was needed, and the data of all seismographs were deciphered at any point on Earth. It was then that Charles Richter got down to business. The American began to use the decimal logarithm.

The measurement of the oscillation amplitude was directly proportional to the change in the needle on the seismograph. Richter also made adjustments depending on the distance of the area from the epicenter of the earthquake.

Richter magnitude scale was officially registered in 1935. The world began to focus not only on 10 points, but also on the difference of ten points between adjacent marks on the ruler.

A 2-magnitude earthquake is considered 10 times stronger than a 1-magnitude one, and 3-magnitude tremors are 10 times more powerful than a 2-magnitude one, and so on. But how to determine the strength of the shocks? How to find out and determine that the movements of the earth's crust are exactly 3, 7, 9-point?

Richter scale - scores in visual and physical manifestations

The scores will help us measure the frequency of surface shocks. Their power in the bowels of the Earth, where the fault occurred, is greater. Part of the energy goes on the way to the solid crust of the planet. This means that the power is greater, the closer to the surface of the source. One point people do not feel.

Two points will be felt only by residents of the upper floors of skyscrapers, feeling slight vibrations. At three points, the chandeliers swing. Perceptible shaking inside buildings, not even large ones, is four points.

And five-point earthquakes are already felt not only in houses, but also on the streets. At six points, glass may crack, furniture and dishes move. It becomes difficult to stay on your feet during a seven-point earthquake. Cracks spread along the brick walls, flights of stairs can be destroyed, landslides occur on the roads.

With eight points, buildings can collapse, as well as break communications that are located underground. Nine-point tremors lead to unrest on the water, they can cause a tsunami. The soil is cracking.

It crushes and breaks it during 10-magnitude earthquakes. Eleven points... Stop. After all, the Richter scale ends at ten. In fact of the matter. Gaps in people's knowledge led to the mixing of Mercalli and Richter systems.

The surface intensity of shocks in points was measured according to the Italian scale. She, apparently, did not disappear, but unofficially joined the American one. Mercalli has both 11 and 12 points.

At 11, brick buildings will collapse to the ground, only a memory remains of the roads. 12 points - this is a catastrophic earthquake that changes the relief of the earth. Cracks in it reach a width of 10-15 meters.

What do the marks on the true Richter scale tell us? It is based on a magnitude that Mercalli did not take into account. Magnitude measures the energy released during movements in the earth's interior. Consider not the external manifestations of the earthquake, but their inner essence.

Richter scale - magnitude table

If it is possible to determine the scores by observing changes on the surface of the planet, then the magnitude is measured only according to the readings of seismographs. The calculation is based on the type of waves of some typical, average earthquake.

The indicator is put in the logarithm with the maximum amplitude of specific concussions. The magnitude is proportional to this logarithm.

The strength of the energy emitted during an earthquake depends on the size of its source, that is, the length and width of the fault in the rocks. Typical shocks according to Richter can be measured not only whole, but also fractional.

Thus, a magnitude of 4.5 leads to little damage. The fault parameters are only a few meters vertically and in length. A source of several kilometers, as a rule, produces earthquakes with a magnitude of 6.

Fault hundreds of kilometers - magnitude 8.5. The Richter scale also has a ten. But, this is, so to speak, an unrealistic limit. On Earth, there have been no earthquakes with a magnitude higher than 9. Apparently it won't happen.

For the 10th magnitude, a fault depth of more than 100 kilometers is needed. But, at such a depth, the earth is no longer solid, the substance turns into a liquid - the mantle of the planet. The length of the focus, pulling on the top ten, should exceed 1000 kilometers. But such faults are not known to scientists.

Earthquakes with a magnitude of 1 do not occur, or rather, are not recorded by instruments. The weakest tremors felt by both seismographs and people are 2 points. Yes, magnitude indicators are sometimes also called points. But, it’s more correct to pronounce only the number, so that there is no confusion with the Mercalli scale.

There is an approximate relationship between the magnitude of an earthquake and its magnitude. At the same time, it is important to take into account the depth of the shock source. The easiest way to correlate indicators is by looking at the table.

Kilometers	Magnitude
5	5	6	7	8
10	7	8-9	10	11-12
20	6	7-8	9	10-11
40	5	6-7	8	9-10

The table shows that the same magnitude can lead to different damage depending on the depth of the source. There are other reasons to judge what will be earthquake in points? Scores on the Richter scale also depend on the seismic resistance of buildings in the area of tremors, the nature of the soil.

In strong buildings, the force of an earthquake is perceived differently than in houses built without taking into account the possible movements of the earth's crust. Charles Richter talked about this back in the 1930s.

The scientist not only created an international scale, but all his life he fought for reasonable construction, taking into account all the risks of a particular area. It was thanks to Richter that many countries tightened the standards for the construction of buildings.

Therefore, in everyday life, the value of magnitude is called Richter scale.

Earthquake magnitude and earthquake intensity scale

The Richter scale contains arbitrary units (from 1 to 9.5) - magnitudes, which are calculated from vibrations recorded by a seismograph. This scale is often confused with earthquake intensity scale in points(according to a 7 or 12-point system), which is based on the external manifestations of an earthquake (impact on people, objects, buildings, natural objects). When an earthquake occurs, it is its magnitude that first becomes known, which is determined by seismograms, and not the intensity, which becomes clear only after some time, after receiving information about the consequences.

Correct use: « magnitude 6.0 earthquake».

Former misuse: « earthquake measuring 6 on the Richter scale».

Misuse: « magnitude 6 earthquake», « earthquake measuring 6 magnitude on the Richter scale» .

Richter scale

M s = lg ⁡ (A / T) + 1 .66 lg ⁡ D + 3 . 30. (\displaystyle M_(s)=\lg(A/T)+1.66\lg D+3.30.)

These scales do not work well for the largest earthquakes - at M~ 8 is coming saturation.

Seismic moment and Kanamori scale

In the same year, seismologist Hiro Kanamori proposed a fundamentally different estimate of the intensity of earthquakes, based on the concept seismic moment.

The seismic moment of an earthquake is defined as M 0 = μ S u (\displaystyle M_(0)=\mu Su), where

μ - shear modulus rocks, about 30 GPa;
S- the area where geological faults are observed;
u- average displacement along the faults.

Thus, in SI units, the seismic moment has the dimension Pa × m² × m = N × m.

The Kanamori magnitude is defined as

M W = 2 3 (lg ⁡ M 0 − 16 , 1) , (\displaystyle M_(W)=(2 \over 3)(\lg M_(0)-16,1),)

where M 0 is the seismic moment expressed in dyne×cm (1 dyne×cm is equivalent to 1 erg, or 10 −7 N×m).

The Kanamori scale is in good agreement with earlier scales. 3 < M < 7 {\displaystyle 3 and is better suited for assessing large earthquakes.

Common misconceptions

The magnitude characterizes an earthquake as an integral, global event and is not an indicator of the intensity of an earthquake felt at a specific point on the Earth's surface. The intensity 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 rocks, the strength of earthquakes with the same magnitude can differ by 2-3 points.
Magnitude is a dimensionless quantity, it is not measured in points.
Correct use: « earthquake with magnitude 6.0», « earthquake measuring 5 magnitude on the Richter scale»
Misuse: « magnitude 6 earthquake», « earthquake measuring 6 on the Richter scale».

Richter scale

The seismic energy released in a 1 megaton nuclear explosion is equivalent to an earthquake with a magnitude of about 6.0. It is worth noting that only a small part of the energy of the explosion is converted into seismic vibrations.

Frequency of earthquakes of different magnitude

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See what the "Richter Scale" is in other dictionaries:

RICHTER SCALE, a classification of earthquake strength created and introduced in 1935 by the American geologist Charles Richter (1900 1985). The scale is based on the principle of the logarithm: each division increases by 10 times, and its base is ... ...

Richter scale- A scale graduated in Arabic numerals from 0 to 10, used to measure the strength of an earthquake with a standard seismograph 100 km from its epicenter ... Geography Dictionary

Richter scale- The magnitude of the earthquake is based on the amplitude of the most distant trace recorded by the seismograph at a distance of 100 km from the epicenter of the earthquake [A.S. Goldberg. English Russian Energy Dictionary. 2006] Topics energy in general EN … Technical Translator's Handbook

RICHTER SCALE- In damage management: classification of earthquakes by magnitude, based on the assessment of the energy of seismic waves that occur during earthquakes. The scale uses a logarithmic scale, so that each integer value on the scale indicates... ... Insurance and risk management. Terminological dictionary

Richter scale - classification of earthquakes by magnitude- Richter scale classification of earthquakes by magnitude, based on the assessment of the energy of seismic waves that occur during earthquakes. The scale was proposed in 1935 by the American seismologist Charles Richter (1900-1985), theoretically ... ... Encyclopedia of newsmakers

RICHTER SCALE, see RICHTER SCALE ... Scientific and technical encyclopedic dictionary

Scale for estimating the intensity of an earthquake on the Earth's surface. Sh.s. There are two types: based on the assessment of the energy of seismic waves that occur during earthquakes (Richter scale) and the assessment of the intensity of the manifestation of an earthquake on ... ... Emergencies Dictionary

MERCALLI SCALE, a 12 division scale used to measure the strength of earthquakes. Named after the Italian seismologist Giuseppe Mercalli (1850-1914). Based on the damage caused at each point and varies from place to place. Scales... Scientific and technical encyclopedic dictionary

The magnitude of an earthquake is a measure of the energy released during an earthquake in the form of seismic waves. The original magnitude scale was proposed by Richter in 1935, therefore, in everyday life, the magnitude value is erroneously called the scale ... ... Wikipedia

This term has other meanings, see Scale (meanings). A scale is a sign system for which a homomorphic mapping is given, which puts one or another element of the scale in correspondence with real objects. Formally, a tuple is called a scale, ... ... Wikipedia

Books

Richter scale, Evgeny Stakhovsky. "Stakhovsky effect" - an emotional reaction, a sense of satisfaction experienced from obtaining new knowledge, the practical benefits of which are not obvious. This Time It's All About... audiobook

Richter scale created to determine the strength of the earth's vibrations. In other words, the ruler helps to establish the power of earthquakes. The system is international. The Italian Mercalli began to develop it. Who is Richter and why did he take the laurels from his predecessor? We will find out.

History of the Richter scale

Richter earthquake scale adopted in the 1930s. The Mercalli system is not just renamed, but refined. The Italian was sluggish for a 12-point basis. The minimum shocks are one.

Earthquakes from 6 points were recognized as strong. This did not suit all states. In Russia, for example, they were guided by 10, and in Japan by 7-point limits. Meanwhile, the age of globalization has arrived.

A single standard was required so that the data of all seismographs were understandable at any point on the Earth. This is where Charles Richter got involved. The American suggested using the decimal logarithm.

The calculation of the oscillation amplitude is directly proportional to the deflection of the needle on the seismograph. At the same time, Richter introduced an amendment in accordance with the remoteness of the area from the epicenter of the earthquake.

Richter magnitude scale was officially adopted in 1935. The world began to focus not just on 10 points, but also on a 10-point difference between adjacent marks on the ruler.

A 2-point earthquake is 10 times stronger than a 1-point earthquake. 3-point pushes are 10 times more powerful than 2-point pushes, and so on. But, how to determine the strength of concussions? How to understand that the movements of the earth's crust are exactly 3, 7, 9-point?

Richter scale - points in visual and physical manifestations

The scores help measure the intensity of surface tremors. Their strength in the bowels of the Earth, where the rift occurs, is greater. Part of the energy is lost on the way to the solid crust of the planet. It turns out that the intensity is higher, the closer to the surface of the source. 1 point is not perceptible by people.

2 points are recognized only on the upper floors of skyscrapers, weak vibrations are felt. At 3 points, the chandeliers swing. Perceptible shaking inside buildings, even low-rise ones, is 4 points.

5-magnitude earthquakes are detected not only in houses, but also on the street. At 6 points, glass can burst, furniture and dishes move. It becomes difficult to stay on your feet during a 7-magnitude earthquake. Cracks spread along the brick walls, flights of stairs collapse, landslides form on the roads.

At 8 points, buildings are already collapsing, as well as communications laid underground. 9-magnitude tremors lead to unrest in water bodies, can cause, for example, a tsunami. The soil is cracking.

It is crushed and broken during 10-magnitude earthquakes. 11 points… Stop. After all, the Richter scale ends at ten. In fact of the matter. Gaps in the knowledge of the inhabitants led to a mixture of the systems of Mercalli and Richter.

The surface intensity of shocks in points was measured according to the Italian scale. She, apparently, has not sunk into oblivion, but unofficially joined the American one. Mercalli has both 11 and 12 points.

At 11, brick buildings will collapse to the ground, only a reminder remains of the roads. 12 points is a catastrophic earthquake that changes the relief of the earth. Cracks in it reach a width of 10-15 meters.

Now let's figure out what the marks of the true Richter scale say. It is "tied" to the magnitude, which Mercalli did not take into account. The magnitude determines the energy released during movements in the earth's interior. It is not the external manifestations of the earthquake that are considered, but its internal essence.

Richter scale - magnitude table

If you can determine the scores by observing changes on the surface of the planet, then the magnitude is calculated only from the readings of seismographs. The calculations are based on the type of waves of some typical, averaged earthquake.

The indicator is put in the logarithm with the maximum amplitudes of specific shaking. The magnitude is proportional to this logarithm.

So, a magnitude of 4.5 leads to minor damage. The fault parameters are only a few meters vertically and in length. A source of several kilometers, as a rule, produces earthquakes with a magnitude of 6.

Fault hundreds of kilometers - magnitude 8.5. The Richter scale also has 10. But, this is, so to speak, an unrealistic limit. On Earth, there have been no earthquakes with a magnitude higher than 9. Apparently it won't happen.

Kilometers	Magnitude
5	5	6	7	8
10	7	8-9	10	11-12
20	6	7-8	9	10-11
40	5	6-7	8	9-10

It can be seen that the same magnitude can lead to different damage depending on the depth of the source. There are other reasons to judge what will be earthquake in points? Scores on the Richter scale also depend on the seismic resistance of buildings in the area of tremors, the nature of the soil.

In solid buildings, the force of an earthquake is perceived differently than in houses built without taking into account the possible movements of the earth's crust. Charles Richter talked about this back in the 1930s.