An earthquake is a physical vibration of the lithosphere - a solid shell of the earth's crust, which is in constant motion. Often such phenomena occur in mountainous areas. It is there that underground rocks continue to form, as a result of which the Earth's crust is especially mobile.

Causes of the disaster

The causes of earthquakes can be different. One of them is the displacement and collision of oceanic or continental plates. With such phenomena, the surface of the Earth vibrates noticeably and often leads to the destruction of buildings. Such earthquakes are called tectonic. With them, new depressions or mountains can form.

Volcanic earthquakes occur due to the constant pressure of red-hot lava and various gases on the earth's crust. Such earthquakes can last for weeks, but, as a rule, they do not carry massive destruction. In addition, such a phenomenon often serves as a prerequisite for a volcanic eruption, the consequences of which can be much more dangerous for people than the disaster itself.

There is another type of earthquakes - landslides, which occur for a completely different reason. Groundwater sometimes forms underground voids. Under the onslaught of the earth's surface, huge sections of the Earth fall down with a roar, causing small vibrations that are felt many kilometers from the epicenter.

Earthquake scores

To determine the strength of an earthquake, they generally resort to either a ten- or twelve-point scale. The 10-point Richter scale determines the amount of energy released. The 12-point Medvedev-Sponheuer-Karnik system describes the impact of vibrations on the Earth's surface.

The Richter scale and the 12-point scale are not comparable. For example: scientists explode a bomb underground twice. One at a depth of 100 m, the other at a depth of 200 m. The energy expended is the same, which leads to the same Richter estimate. But the consequence of the explosion - the displacement of the crust - has a different degree of severity and affects the infrastructure in different ways.

Degree of destruction

What is an earthquake in terms of seismic instruments? The phenomenon of one point is determined only by the equipment. 2 points can be palpable animals, and also, in rare cases, especially sensitive people located on the upper floors. 3 points feels like the vibration of a building from a passing truck. A magnitude 4 earthquake causes the windows to rattle slightly. At five points, the phenomenon is felt by everyone, and it does not matter where the person is, on the street or in the building. An earthquake of 6 points is called strong. It horrifies many: people run out into the street, and cracks form on some walls of houses. A score of 7 causes cracks in almost all houses. 8 points knock over architectural monuments, factory chimneys, towers, and cracks appear on the soil. 9 points lead to severe damage to houses. Wooden structures either tip over or sag heavily. 10-point earthquakes lead to cracks in the ground, up to 1 meter thick. 11 points is a disaster. Stone houses and bridges collapse. Landslides occur. Not a single building can withstand 12 points. With such a catastrophe, the relief of the Earth changes, the flow of rivers deviates and waterfalls appear.

Japanese earthquake

V pacific ocean 373 km from the capital of Japan, Tokyo, there was a devastating tremor. It happened on March 11, 2011 at 14:46 local time.

A magnitude 9 earthquake in Japan caused massive destruction. The tsunami that hit the east coast of the country flooded a large part of the coastline, destroying houses, yachts and cars. The height of the waves reached 30-40 m. The immediate reaction of people prepared for such tests saved their lives. Only those who left their homes on time and found themselves in a safe place were able to avoid death.

Japan earthquake victims

Unfortunately, there were no casualties. The Great East Japan Earthquake, as the event became officially known, claimed 16,000 lives. 350,000 people in Japan were left homeless, which led to internal migration. Many settlements were wiped off the face of the Earth, there was no electricity even in large cities.

The earthquake in Japan radically changed the habitual way of life of the population and severely undermined the economy of the state. The losses caused by this disaster were estimated by the authorities at 300 billion dollars.

What is an earthquake from the point of view of a resident of Japan? It is a natural disaster that keeps the country in constant turmoil. The looming threat is forcing scientists to invent more accurate earthquake detection instruments and more durable materials for the construction of buildings.

Affected Nepal

On April 25, 2015 at 12:35 pm, an almost 8-magnitude earthquake occurred in the middle part of Nepal, lasting 20 seconds. The next one happened at 13:00. Aftershocks lasted until May 12. The reason was a geological fault on the line where the Hindustan plate meets the Eurasian. As a result of these shocks, the capital of Nepal, Kathmandu, moved south by three meters.

Soon the whole earth learned about the destruction that the earthquake had brought in Nepal. Cameras installed right on the street recorded the moment of tremors and their consequences.

26 regions of the country, as well as Bangladesh and India, felt what an earthquake is. Reports of missing people and collapsed buildings are still coming to the authorities. 8.5 thousand Nepalese lost their lives, 17.5 thousand were injured, and about 500 thousand were left homeless.

The earthquake in Nepal caused a real panic among the population. And it is not surprising, because people lost their relatives and saw how quickly what was dear to their hearts was collapsing. But problems are known to unite, as has been proven by the people of Nepal who have worked side by side to restore the city streets to their former glory.

recent earthquake

On June 8, 2015, an earthquake of magnitude 5.2 occurred on the territory of Kyrgyzstan. This is the last earthquake that exceeded 5 points.

Speaking of a terrible natural disaster, one cannot fail to mention the earthquake on the island of Haiti, which occurred on January 12, 2010. A series of shocks from 5 to 7 points claimed 300,000 lives. The world will remember this and other similar tragedies for a long time to come.

In March, the coast of Panama learned the magnitude of the earthquake at 5.6 points. In March 2014, Romania and southwestern Ukraine learned first hand what an earthquake is. Fortunately, there were no casualties, but many experienced the excitement of the elements. Per Lately earthquake scores did not cross the brink of disaster.

Earthquake frequency

So, the movement of the earth's crust has various natural causes. Earthquakes, according to seismologists, occur up to 500,000 annually in different parts of the Earth. Of these, approximately 100,000 are felt by people, and 1,000 cause serious damage: destroy buildings, highways and railways, cuts off power lines, sometimes blows entire cities underground.

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.

— classification of earthquakes by magnitudes, based on the assessment of energy seismic waves that occur during earthquakes. The scale was proposed in 1935 by the American seismologist Charles Richter (1900-1985), theoretically substantiated jointly with the American seismologist Beno Gutenberg in 1941-1945, and has become widespread throughout the world.

The Richter scale characterizes the amount of energy that is released during an earthquake. Although the scale of magnitudes is in principle unlimited, 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 on the scale indicates an earthquake ten times the magnitude of the previous one.

An earthquake with a magnitude of 6.0 on the Richter scale will cause 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 in the source of an earthquake, with an increase in magnitude by one, increases by about 30 times.
The magnitude of an earthquake is a dimensionless value 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 the methods for determining the magnitudes of near, distant, shallow (shallow) and deep earthquakes. The magnitudes determined for 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 destruction;
8.5 is the strongest known earthquake.

Scientists believe that earthquakes stronger than those with a magnitude of 9.0 cannot occur on Earth. It is known that each earthquake is a shock or a series of shocks that occur as a result of the displacement of rock masses along the fault. Calculations showed that the size of the earthquake source (that is, the size of the area on which the displacement occurred rocks, which determine the strength of an earthquake and its energy) with weak, barely perceptible tremors by a person, it 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 already kilometers. The centers of the most powerful, catastrophic earthquakes are 500-1000 kilometers long and go to a depth of 50 kilometers. The focus of the largest earthquake recorded on Earth is 1000 x 100 kilometers, i.e. close to the maximum length of faults known to scientists. A further increase in the depth of the focus is also impossible, since the terrestrial matter at depths of more than 100 kilometers passes into a state close to melting.

The magnitude characterizes an earthquake as an integral, global event and is not an indicator of the intensity of an earthquake felt at a particular 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 rocks, 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 an earthquake (the effect of its impact on the surface), i.e. measures the damage done to a given area. The score is established during the survey of the area according to the magnitude of the destruction of ground structures or deformations of the earth's surface.

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

Estimation of intensity, which is based on the everyday consequences of an earthquake, easily distinguishable even by an inexperienced observer, in seismic scales different countries different. For example, in Australia, one of the degrees of shaking is compared to “how a horse rubs against a veranda post”, in Europe the same seismic effect is described as “bells begin to ring”, in Japan there is an “overturned stone lantern”.

The material was prepared on the basis of information from open sources

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 the 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.

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

The most popular scale for assessing 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 perceptible, while a magnitude of 7 corresponds to the lower limit of destructive earthquakes covering large areas. The intensity of earthquakes (cannot be estimated by magnitude) is estimated by the damage they cause in populated areas.

intensity scale

Intensity is a qualitative characteristic of an earthquake and indicates the nature and scale of the impact of an earthquake on the earth's surface, on people, animals, as well as on natural and artificial structures in the earthquake area. Several intensity scales are used in the world: in Europe - the European macroseismic scale (EMS), in Japan - the scale of the Japan Meteorological Agency (Shindo), in the USA and Russia - the modified Mercalli scale (MM):

1. score (imperceptible) - soil vibrations noted by the device;
2. points (very weak) - the earthquake is felt in some cases by people who are in a calm state;
3. points (weak) - fluctuation is noted by few people;
4. points (moderate) - the earthquake is noted by many people; swaying of windows and doors is possible;
5. points (quite strong) - swinging hanging objects, creaking floors, rattling windows, shedding whitewash;
6. points (strong) - light damage to buildings: thin cracks in plaster, cracks in furnaces, etc.;
7. points (very strong) - significant damage to buildings; cracks in the plaster and breaking off of individual pieces, thin cracks in the walls, damage chimneys; cracks in wet soils;
8 points (destructive) - destruction in buildings: large cracks in the walls, falling cornices, chimneys. Landslides and cracks up to several centimeters wide on mountain slopes;
9. points (devastating) - collapses in some buildings, collapse of walls, partitions, roofs. Collapses, screes and landslides in the mountains. The speed of crack propagation can reach 2 km/s;
10. points (destroying) - collapses in many buildings; the rest are seriously damaged. Cracks in the ground up to 1 m wide, collapses, landslides. Due to the blockages of river valleys, lakes arise;
11. points (catastrophe) - numerous cracks on the surface of the Earth, large landslides in the mountains. General destruction of buildings;
12. points (severe catastrophe) - a change in the relief on a large scale. Huge collapses and landslides. General destruction of buildings and structures.