In this article, we will look at causes of earthquakes. The very concept of an earthquake is known to all people, and even children, but what are the reasons that suddenly the earth underfoot begins to move and everything around collapses?
First of all, it must be said that earthquakes are conditionally divided into several types: tectonic, volcanic, landslide, artificial and man-made. We will briefly review all of them right now. If you want to know, be sure to read to the end.
Tectonic causes of earthquakes
Most often, earthquakes occur due to the fact that they are in constant motion. The top layer of lithospheric plates is called tectonic plates. By themselves, the platforms move unevenly and constantly put pressure on each other. However, they remain dormant for a long time.
Gradually, the pressure builds up, as a result of which the tectonic platform makes a sudden push. It is he who produces vibrations of the surrounding rock, which is why an earthquake occurs.
San Andreas Fault
Transform Rifts are huge cracks in the Earth where platforms "rub" against each other. Many readers should be aware that the San Andreas Fault is one of the most famous and longest transform faults in the world. It is located in California in the USA.
Photo of the San Andreas Fault Platforms moving along it cause devastating earthquakes in the cities of San Francisco and Los Angeles. An interesting fact: in 2015, Hollywood released a film called "The San Andreas Fault". He talks about the corresponding catastrophe.
Volcanic causes of earthquakes
Volcanoes are one of the causes of earthquakes. Although they do not produce strong ground vibrations, they last long enough. The causes of the tremors are related to the fact that deep in the depths of the volcano, tension is growing, formed by lava and volcanic gases. As a rule, volcanic earthquakes last weeks and even months.
However, history knows cases of tragic earthquakes of this type. An example is the Krakatoa volcano located in Indonesia, which erupted in 1883.
Krakatau is still sometimes excited. Real photo. The force of its explosion was at least 10 thousand times greater than the force. The mountain itself was almost completely destroyed, and the island broke into three small parts. Two-thirds of the land disappeared under water, and the rising tsunami destroyed everyone who still had a chance to escape. More than 36,000 people died.
Landslide causes of earthquakes
Earthquakes caused by giant landslides are called landslides. They have a local character, and their strength, as a rule, is small. But even here there are exceptions. For example, in Peru, in 1970, a landslide, with a volume of 13 million cubic meters, descended from Mount Huascaran at a speed of over 400 km / h. About 20,000 people died.
Man-made causes of earthquakes
Earthquakes of this type are caused by human activity. For example, artificial reservoirs in places not intended for this by nature provoke pressure on the plates with their weight, which serves to increase the number and strength of earthquakes.
The same applies to the oil and gas industry, when a large amount of natural materials is extracted. In a word, man-made earthquakes occur when a person took something from nature from one place and transferred it to another without asking.
Man-made causes of earthquakes
By the name of this type of earthquake, it is easy to guess that the fault for it lies entirely with the person.
For example, North Korea tested a nuclear bomb in 2006, which caused a small earthquake recorded in many countries. That is, any activity of the inhabitants of the earth, which is obviously guaranteed to entail an earthquake, is an artificial cause of this type of disaster.
Can earthquakes be predicted?
Indeed it is possible. For example, in 1975, Chinese scientists predicted an earthquake and saved many lives. But it is impossible to do this with a 100% guarantee even today. An ultra-sensitive device that registers an earthquake is called a seismograph. On a spinning drum, the recorder marks the vibrations of the earth.
seismograph Animals before earthquakes also acutely feel anxiety. Horses begin to rear up for no apparent reason, dogs bark strangely, and snakes crawl out of their holes to the surface.
Earthquake scale
As a rule, the strength of earthquakes is measured by the Earthquake Scale. We will give all twelve points so that you have an idea of \u200b\u200bwhat it is.
- 1 point (imperceptible) - the earthquake is recorded exclusively by instruments;
- 2 points (very weak) - can only be seen by pets;
- 3 points (weak) - noticeable only in some buildings. Feelings like driving a car over bumps;
- 4 points (moderate) - noticed by many people, can cause windows and doors to move;
- 5 points (quite strong) - glass rattles, hanging objects sway, old whitewash may crumble;
- 6 points (strong) - with this earthquake, light damage to buildings and cracks in low-quality buildings are already noted;
- 7 points (very strong) - at this stage, the buildings suffer significant damage;
- 8 points (destructive) - there are destructions in buildings, chimneys and cornices fall, cracks of several centimeters can be seen on the slopes of the mountains;
- 9 points (devastating) - earthquakes cause collapses of some buildings, old walls collapse, and the crack propagation speed reaches 2 centimeters per second;
- 10 points (destructive) - collapses in many buildings, in most - serious destruction. The soil is streaked with cracks up to 1 meter wide, landslides and landslides all around;
- 11 points (catastrophe) - large collapses in the mountains, numerous cracks and a picture of the general destruction of most buildings;
- 12 points (strong catastrophe) - the relief is globally changing almost before our eyes. Huge collapses and total destruction of all buildings.
In principle, any catastrophe caused by tremors of the earth's surface can be assessed on a twelve-point scale of earthquakes.
In the lessons of natural history, we study volcanoes and earthquakes. We already know the basic concepts - the types and structure of volcanoes, why and how they erupt, where earthquakes most often occur and why they are dangerous ... 
Since ancient times, volcanoes and earthquakes have been considered the most large-scale and destructive natural phenomena, but at the same time, especially volcanoes, attract and fascinate with their strength and power. Every year one of them wakes up and destroys everything around, bringing destruction, death and material losses to people. However, despite their fear, they
attract the attention of thousands of tourists; settlements and even large cities are being built around many active volcanoes.
The best of the best...
the most beautiful considered one of the most active active volcanoes on Earth and the youngest of the Hawaiian volcanoes - Kilaue, it is located in the state of Hawaii, USA. The eruption of this volcano has been going on for 28 years, and it is the largest (about 4.5 km in diameter of the crater) active on Earth. Here you can admire intricately frozen lava and "lunar" landscapes. Tourists are allowed to the volcano. Kilaue is believed to be the home of Pele, the Hawaiian goddess of volcanoes. Lava formations are named after her - "Pele's tears" (drops of lava that cooled in the air and took the form of a tear) and "Pele's hair" (filaments of volcanic glass formed as a result of the rapid cooling of lava when flowing into the ocean). 
Interesting Facts.
When something happens eruption, this means not only the formation of ash clouds, which can prevent sunlight from entering the region, and cause a few days of cooling. It also releases sulfur gases. When they are ejected to the level of the stratosphere, aerosols from sulfuric acid are formed, they spread like a blanket over the entire planet. Since these aerosols are above the rain level, they are not washed away. They linger there, reflecting sunlight and cooling the surface of the Earth.
On average, every year on our planet there are about a million tremors. Most of them, fortunately, are almost imperceptible and can only be recorded with the help of sensitive instruments, but some shocks are of considerable force. On average, 15 to 25 strong earthquakes occur annually in the world.
Movements inside the earth's crust lead to the appearance of earthquakes - shaking of the earth's surface. They may be associated with volcanic activity or with movements and their parts. The center of an earthquake can be located deep below the surface of the Earth - at a depth of up to several hundred kilometers, in which case they are felt quite weakly on the surface. The most destructive force are those earthquakes that occur at a depth of 20-50 km. The place on the earth's surface closest to the center of the earthquake is called the epicenter - it is at this point that the earthquake is strongest.
Hundreds of thousands of earthquakes are recorded every year on the globe. However, most of them are weak and we do not notice them. The strength of earthquakes is estimated by the intensity of destruction on the surface of the Earth and is measured on a twelve-point scale.
Earthquakes of magnitude 1-2 pass unnoticed by most people, but they can be felt by animals that are more sensitive to the movements of the earth's surface.
Shocks with a force of 3 points are felt only by people who are at rest, and 4 points are already felt by everyone.
Earthquakes of 5 points cause the movement of light objects (for example, dishes), chandeliers sway, open doors slam.
Earthquakes of magnitude 6-7 cause damage to buildings, but the walls remain intact. Structures designed with seismic activity in mind withstand such earthquakes.
6-9 points lead to serious destruction of houses, it is difficult for people to stay on their feet, landslides occur in the mountains.
At 10-11 points, any structures turn into ruins, roads, pipelines, railway rails are badly damaged, the earth cracks.
12 points - the most destructive earthquakes, leading to the complete destruction of settlements and strong changes in the relief (rocks, clefts, lakes, rivers change their channels).
Earthquakes are measured with a special instrument called seismograph. It registers the slightest vibrations of the earth's crust.
With the help of seismographs, it is possible to predict in a few hours, since any eruption begins with shocks inside the earth's crust, after which magma rushes up.
Signs of a nearby earthquake
- the smell of gas in an area where it was not noticed before,
- disturbance of birds and domestic animals,
- flashes in the form of scattered light lightning,
- sparking of closely spaced but not touching electrical wires,
- bluish glow of the inner surface of the walls of houses;
- spontaneous ignition of fluorescent lamps.
There are areas of increased seismic activity - those in which earthquakes occur more often. In Russia, this is Southern Siberia. Special precautions are taken in such areas. Firstly, the probability of an earthquake is taken into account in the construction of housing and other structures, since it is the destruction of buildings that causes the most serious damage during an earthquake. Secondly, mechanisms are being created to quickly alert the population, especially in areas with high volcanic activity.
It is no less dangerous if the epicenter of the earthquake is in the ocean, since in this case huge waves up to 30 m high arise.
In the open sea or ocean, tsunamis are not dangerous, therefore, in case of danger, all ships in the port immediately go to sea. On the coast, these huge waves cause serious destruction.
Eruption
There are volcanoes on every continent except Australia, even Antarctida. But mostly they are located in seismically active zones, breaks in the earth's crust and at the junctions of tectonic plates. On the territory of Russia, active volcanic activity is manifested in Kamchatka, the Kuril Islands and Sakhalin Island. Not only active, but also so-called "sleeping volcanoes" are located here. Moreover, the latter are no less dangerous, since they can wake up at any time. The most active volcanoes erupt once every few years, and all active volcanoes erupt once every 10-15 years.
Harbingers of eruptions
increased gas emission;
rise in soil temperature on the slopes of the volcano;
intensification of its seismic activity, expressed in a series
earth tremors of different strength;
swelling of the volcanic cone and change in the slope of its surface.
During an eruption, hot and molten magma pours out of the crater of a volcano in the form of lava flows. Getting into this zone is deadly and can at best lead to severe burns. Under the influence of air from above, lava flows are covered with a dark and rather dense crust, on which you can sometimes even walk, but this is extremely dangerous because of the threat of not only burning your shoes, but also falling into a hot stream, the temperature of which is several hundred degrees.
Mount Pinatubo on the Philippine island of Luzon, located northeast of Java, last erupted in 1991. Its eruption was not as powerful as, say, the eruption of Vesuvius in antiquity, but a lot of ash was thrown out. Tropical rains immediately caused a powerful mudflow. It rolled down in twelve to eleven wide streams. Under a layer of mud were several villages and towns. About two thousand cubic kilometers of ash and volcanic stones, pumice and sand were washed away from the slopes of the volcano. When future archaeologists begin excavations at the site of Philippine Pompeii, they will be surprised not only by the poverty of peasant belongings, but also by the abundance of military equipment. Under the mudflow was equipment, which did not have time to evacuate from the American military bases. The soldiers themselves managed to escape.
Being near a crater or on the slope of a volcano is dangerous not only during an eruption, but also because various poisonous gases often escape from the ground. Such outlets of gases are called fumaroles. Often carbon dioxide, which has neither color nor smell, accumulates in relief depressions and can cause severe, often fatal poisoning. Often jets of red-hot steam escape from cracks in the ground.
During eruptions from the crater, in addition to molten magma, various stones are ejected: from the smallest particles to huge blocks. They are ejected from the vent to a great height and scatter in all directions. Occur during eruptions and powerful mud flows like mudflows. But perhaps even more terrible phenomenon can be called the fall of hot ash, which not only destroys everything around, but can also cover entire cities with a thick layer. If you fall into such an ash fall, it is almost impossible to escape.
earthquakes
An earthquake is understood as underground shocks and vibrations of the earth's surface caused by tectonic processes and transmitted over long distances in the form of elastic vibrations. The greatest number of earthquakes is confined to zones of active faults in the earth's crust and to mid-ocean ridges. Earthquakes also occur within relatively stable areas of the continents, but they are rare, not as strong and destructive as in seismically active zones. However, destructive earthquakes are still possible anywhere in the world.
Some causes of earthquakes
1. Natural natural causes:
volcanic activity;
the fall of celestial bodies;
large mountain falls and landslides.
2. Human activity:
dam breaks;
ultrafast filling of deep (more than 100 m) reservoirs; injection of industrial water into underground mine workings or into exhausted gas and oil fields; subsidence of deep quarries and mines.
The consequences of earthquakes
In our country, an international 12-point intensity scale has been adopted, which describes the strength of an earthquake at its epicenter.
So, during a 6-magnitude earthquake, thin and medium cracks appear in the walls in buildings, sometimes up to 1 cm wide. Landslides are observed in mountainous areas.
Further destruction is on the rise, and even with a 9-point earthquake, houses are destroyed or very strongly destroyed, trees, monuments, power lines, television towers fall, pipelines break, the rails of the railway bed are bent, and roads are damaged. Severe landslides, landslides, shedding of soil often occur.
With a 10-point earthquake, up to 75% of buildings, bridges, dams are destroyed, railway tracks are displaced, the asphalt pavement of roads is bent, numerous soil ruptures and landslides occur.
At 11 points, buildings and bridges are completely destroyed, the terrain is disturbed, and with an earthquake of 12 points, everything built by man is completely destroyed, lakes disappear, river beds change, the shape and outlines of mountain ranges change.
During an earthquake, a series of shocks and shaking is observed, accompanied by a rumble and rumble coming from the depths of the earth. Due to the formation of faults and thrusts, cracks sometimes run up to several meters long on the ground. The earth is shaking, resembling the deck of a ship during a severe storm. Abysses are formed and immediately close, which absorb everything that was on the surface at that moment - houses, cars, people ... Blocks of rocks stick out from under the ground and move in different directions. After an earthquake, the surface of the earth resembles a heap of ice hummocks.
Earthquake prediction
Until quite recently, it seemed that the processes causing earthquakes are so grandiose and complex that they are inaccessible to direct observation and their exact forecast is impossible. But in recent years, the idea that the approach of destructive underground storms can be predicted from changes in the physical properties of the rocks that form the upper layer of the earth's crust has received real confirmation. Scientists geophysicists have established that the echoes of monstrous shifts in the bowels of the earth reach its surface in the form of very weak, barely noticeable movements, which were called the "dance of the mountains." A few days before the earthquake, the mountain colossi begin to sway, the distances between them change, albeit by a negligible amount. It can be noticed only with the help of a quantum generator-laser.
The peculiarity of an earthquake is that the destruction of objects, including those of a natural nature (rocks, mountain ranges, large trees, etc.), occurs in a short time - a matter of tens of seconds, while the cause of human casualties is very rarely is the direct vibration of the soil (with the exception of its breaks). Most people suffer from falling trees, stones, building walls, glass, etc.
The presence and nature of injuries depend on where the person was at the time of the earthquake. If in a building, then it all depends on the design of the building, its number of storeys and seismic resistance. Multi-storey non-seismic buildings made of concrete panels are the most dangerous. During an earthquake, they fold like a house of cards, and the people who survived at the same time receive a wide variety of injuries, wounds and fractures, as well as the most unpleasant damage to the body - compression syndrome.
When being in an open area, injuries are possible from falling trees, detached rocks, rockfalls, natural disasters and human behavior when entering a dangerous zone, formation of cracks in the ground. Injuries correspond to the cause of occurrence. When a tree falls, these are fractures and compression, wounds. When falling into a crack, everything depends on its depth and the ability to quickly detect the victim or the ability to get out of it yourself.
In seismic areas, where there is a high probability of earthquakes with a magnitude of 7 or more points, half of the population of our planet lives and about 40% of all cities in the world are located. In terms of the number of earthquake victims, they are on 2 hurricanes and floods, and in terms of economic damage - 3rd place after among the first four causes (floods, hurricanes, droughts).
Read more about this topic on this website:
Features of survival in the mountains 
Jungle Survival Features Survival in the taiga 
Survival in arctic conditions
Sometimes the earth's crust starts to move: an earthquake occurs - a formidable natural phenomenon that everyone has probably heard of. Up to a million weak and several thousand strong earthquakes are registered annually.
Strong earthquakes can cause severe damage. In a few seconds, the surrounding area can become unrecognizable from the destroyed buildings and structures. Earthquakes often kill a lot of people.
Earthquakes usually occur near plate boundaries. As you already know, these plates are in constant motion. Plates move both horizontally and vertically. When the edges of the adjacent plates "get stuck", the plates move, tremors occur. Areas where earthquakes are especially frequent are called seismically active (from the Greek word "seismos" - earthquake).
The place where the rupture and displacement of rocks occurs is called the focus of an earthquake. It is usually found at a depth of several kilometers.
Above the source on the earth's surface is the place of the greatest manifestation of the earthquake. It is called the epicenter (from the Greek word "epi" - above).
Earthquakes are dangerous because of their suddenness. Since ancient times, people have sought to learn how to predict these natural phenomena.
A whole network of stations has been organized in the world, which constantly monitor the state of the earth's crust. They register everything, even weak earthquakes, capturing those waves that diverge from the place of underground shocks. Unfortunately, it is not yet possible to reliably and accurately predict earthquakes.
Volcanic eruptions are a formidable and dangerous natural phenomenon for people. Volcanoes are figuratively called fire-breathing mountains. The very name of these mountains comes from the name of the ancient Roman god of fire, Vulcan.
The volcano is a mountain, in the upper part of which there is a recess - a crater, to which the vent approaches. Under the volcano is a special chamber - a magma chamber.
Magma is the molten substance of the mantle (from the Greek word "magma" - dough, mess).
Volcanoes form in areas of the Earth where deep cracks in the earth's crust create pathways for magma to reach the surface. Trying to free itself from the colossal pressure that exists at depth, magma rushes up the vent and pours out onto the earth's surface. Magma erupting to the surface is called lava. This usually happens near plate boundaries. The areas of the greatest distribution of volcanoes coincide with seismically active areas.
If the lava is thick, viscous, then it cools down quite quickly, forming a high mountain with steep slopes, having the shape of a cone. This is a conical volcano. More fluid lava spreads faster and cools more slowly, so it has time to flow over considerable distances. The slopes of such a volcano are gentle. This is a shield volcano.
Sometimes very viscous lava can solidify in a channel, forming a plug. However, after some time, pressure from below pushes it out, a strong eruption occurs with the release of stone blocks into the air - volcanic bombs.
During an eruption, not only lava comes to the surface, but also various gases, water vapor, volcanic dust, clouds of ash. Dust and ashes are carried hundreds and thousands of kilometers. During the grandiose eruption of the Krakatau volcano in Indonesia (1883), particles of volcanic dust and ash formed after the explosion of the volcano flew around the Earth twice.
In the realm of restless land and fire-breathing mountains
Volcanoes that erupted at least once in the memory of mankind are called active. They can erupt continuously or intermittently. If there is no information about volcanic eruptions, they are called extinct.
Usually volcanic eruptions are accompanied by an underground rumble, and sometimes by earthquakes. Lava flows cause fires, destroy roads, flood fields.
Now on land there are several hundred active volcanoes. Every year there are 20-30 eruptions.
In our country, there are many active volcanoes in Kamchatka and the Kuril Islands. The largest of them - Klyuchevskaya Sopka - is located in Kamchatka. Its height is 4688 m. There are many volcanoes at the bottom of the oceans. There are underwater eruptions.
- Name the main areas of distribution of volcanoes.
- Which continent has no volcanoes?
- Where are active volcanoes located in Russia?
- Why do earthquakes occur?
- What is the focus and epicenter of an earthquake?
- What is the structure of a volcano?
- What causes a volcanic eruption?
- How does a volcano erupt?
An earthquake occurs when two sections of plates suddenly shift. The place in the depths where the rupture and displacement of rocks occurs is called the focus of an earthquake. Above it on the earth's surface is the epicenter. Volcanoes are located mainly along the boundaries of the plates. In these places, magma during a volcanic eruption pours out to the surface in the form of lava.
I would be grateful if you share this article on social networks:
Site search.
