MINISTRY OF EDUCATION AND SCIENCE OF THE RUSSIAN FEDERATION
Federal State Budgetary Educational Institution of Higher Professional Education
"RUSSIAN ECONOMIC UNIVERSITY NAMED AFTER G.V. PLEKHANOV"
VOLGOGRAD BRANCH
Test
Life safety
Protection of the population and territory during an earthquake
Volgograd 2014
Introduction
1. Earthquakes
1.1 Causes of earthquakes
2 Earthquake registration
3 Earthquake magnitude
4 Effects of earthquakes
5 Associated phenomena
6 Geographic distribution of earthquakes
7 Earthquake forecast
Protective measures in case of threat and occurrence of earthquakes
Earthquake Safety Measures
Introduction
Even in ancient myths and legends, we find mention of the destructive power of earthquakes. This and the stories of the Bible about the fall of the walls of Jericho in 1100 BC. from the thunderous sounds of the sacred trumpets. This is skillfully inscribed in the "Songs of Hiawatha" references to the falls of heavenly stones (meteorites) and earthquakes in the Rocky Mountains. This is the legend about the destruction of the royal palace by the blinded Samson. Three thousand Philistines were buried under its ruins.
The causes of the Earth's seismic activity should be sought in the deepest bowels of the Earth - the least studied area of geology. The main problem in the study is that scientists could not look deeper than a 4 km well in seismically active zones. A greater number of large earthquakes occur in two seismic zones, the Pacific and the Mediterranean-Trans-Asian. The Pacific zone accounts for 80% of all earthquakes, the Mediterranean-Trans-Asian - 15%, the remaining 5% occur in the remaining seismic zones.
Many unconfirmed predictions caused huge economic damage, and most of the predicted earthquakes never happened. Now the latest scientific and technological achievements are being used, the Earth is being observed from satellites, but accurate predictions do not appear. Earthquakes are the most destructive natural element. From the consequences of seismic activity (fires, destruction of buildings, tsunamis and panic), the largest number of people die. According to statistics, more than 10 thousand people die every year from earthquakes, which is 25 times more than from volcanic eruptions. The strongest seismic tremors only until the middle of the 20th century claimed many human lives: in 1923, as a result of an earthquake in Tokyo, 140 thousand people; in 1946 after the earthquake in Ashgabat - more than 100 thousand people.
1. Earthquakes
Earthquakes, vibrations of the Earth caused by sudden changes in the state of the interior of the planet. These vibrations are elastic waves propagating at high speed in the rock mass. The strongest earthquakes are sometimes felt at distances of more than 1500 km from the source and can be recorded by seismographs (special highly sensitive instruments) even in the opposite hemisphere. The area where oscillations originate is called the source of the earthquake, and its projection on the Earth's surface is called the epicenter of the earthquake. The sources of most earthquakes lie in the earth's crust at depths of no more than 16 km, but in some regions the depths of the sources reach 700 km. There are thousands of earthquakes every day, but only a few of them are felt by humans.
Earthquakes are mentioned in the Bible, in the treatises of ancient scientists - Herodotus, Pliny and Livy, as well as in ancient Chinese and Japanese written sources. Until the 19th century most reports of earthquakes contained descriptions richly flavored with superstition and theories based on scanty and unreliable observations. A series of systematic descriptions (catalogues) of earthquakes was started in 1840 by A. Perry (France). In the 1850s, R. Malle (Ireland) compiled a large catalog of earthquakes, and his detailed report on the earthquake in Naples in 1857 became one of the first strictly scientific descriptions of strong earthquakes.
1 Causes of earthquakes
Although numerous studies have been carried out since ancient times, it cannot be said that the causes of earthquakes are fully understood. According to the nature of the processes in their sources, several types of earthquakes are distinguished, the main of which are tectonic, volcanic and man-made.
Tectonic earthquakes occur as a result of a sudden release of stress, for example, when moving along a fault in the earth's crust (recent studies show that phase transitions in the Earth's mantle that occur at certain temperatures and pressures can also be the cause of deep earthquakes). Sometimes deep faults come to the surface. During the catastrophic earthquake in San Francisco on April 18, 1906, the total length of surface ruptures in the San Andreas fault zone was more than 430 km, the maximum horizontal displacement was 6 m. The maximum recorded value of seismogenic displacements along the fault was 15 m.
Volcanic earthquakes occur as a result of abrupt movements of the magmatic melt in the bowels of the Earth or as a result of ruptures under the influence of these movements. - Man-made earthquakes can be caused by underground nuclear tests, filling reservoirs, oil and gas extraction by fluid injection into wells, blasting during mining, etc. Less powerful earthquakes occur when caves or mine workings collapse.
2 Earthquake registration
A device that records seismic vibrations is called a seismograph, and the recording itself is called a seismogram. The seismograph consists of a pendulum suspended inside the case on a spring and a recording device.
One of the first recording devices was a rotating drum with paper tape. As the drum rotates, it gradually shifts to one side, so that the zero line of the record on the paper looks like a spiral. Every minute, vertical lines are drawn on the chart - time marks; for this, very accurate clocks are used, which are periodically compared with the standard of exact time. To study nearby earthquakes, marking accuracy is required - up to a second or less. In many seismographs, induction devices are used to convert a mechanical signal into an electrical one, in which, when the inertial mass of the pendulum moves relative to the body, the magnitude of the magnetic flux passing through the turns of the induction coil changes. The resulting weak electric current drives a galvanometer connected to a mirror, which casts a beam of light onto the photosensitive paper of the recording device. In modern seismographs, oscillations are recorded digitally using computers.
3 Earthquake magnitude
The magnitude of earthquakes is usually determined on a scale based on seismograph records. This scale is known as the magnitude scale, or the Richter scale (after the American seismologist Ch.F. Richter, who proposed it in 1935). 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 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:
The weakest felt shocks;
/2 - the weakest shocks, leading to small destruction;
Moderate destruction;
/2 are the strongest known earthquakes.
The intensity of earthquakes is estimated in points when examining an area by the magnitude of the destruction of ground structures or deformations of the earth's surface caused by them. For a retrospective assessment of the intensity of historical or more ancient earthquakes, some empirically obtained ratios are used. In the US, intensity is usually assessed using a modified 12-point Mercalli scale.
score. It is felt by a few especially sensitive people in especially favorable circumstances.
points. It is felt by people like a vibration from a passing truck.
points. Dishes and glassware rattle, doors and walls creak.
points. Felt by almost everyone; many sleepers wake up. Loose objects fall.
points. Felt by everyone. Minor damage.
points. Chimneys fall, monuments fall, walls collapse. The water level in the wells is changing. Capital buildings are severely damaged.
points. Brick buildings and frame structures are destroyed. Rails are deformed, landslides occur.
points. Complete destruction. Waves are visible on the earth's surface.
In Russia and some neighboring countries, it is customary to evaluate the intensity of fluctuations in MSK points (12-point Medvedev-Sponheuer-Karnik scale), in Japan - in JMA points (9-point scale of the Japan Meteorological Agency).
The intensity in points (expressed as whole numbers without fractions) is determined by surveying the area in which an earthquake occurred, or by asking residents about their feelings in the absence of destruction, or by calculations using empirically obtained and accepted formulas for this area. Among the first information about the earthquake that occurred, it is its magnitude, and not the intensity, that becomes known. The magnitude is determined from seismograms even at large distances from the epicenter.
4 Effects of earthquakes
Strong earthquakes leave many traces, especially in the epicenter area: the most common are landslides and screes of loose soil and cracks on the earth's surface. The nature of such disturbances is largely determined by the geological structure of the area. In loose and water-saturated soil on steep slopes, landslides and landslides often occur, and a thick layer of water-saturated alluvium in valleys deforms more easily than solid rocks. On the surface of alluvium, subsidence depressions are formed, which are filled with water. And even not very strong earthquakes are reflected in the terrain.
Displacements along faults or the occurrence of surface ruptures can change the planned and vertical position of individual points on the earth's surface along the fault line, as happened during the 1906 earthquake in San Francisco. During an earthquake in October 1915 in the Pleasant Valley in Nevada, a ledge 35 km long and up to 4.5 m high was formed on the fault. .5 m. As a result of the Assam earthquake (India) in June 1897 in the epicentral region, the height of the terrain changed by at least 3 m.
Significant surface deformations are traced not only near faults and lead to a change in the direction of river flow, springing or breaking of watercourses, disruption of the regime of water sources, and some of them temporarily or permanently cease to function, but at the same time new ones may appear. Wells and wells swim with mud, and the water level in them changes significantly. During strong earthquakes, water, liquid mud or sand can be ejected from the ground in fountains.
When moving along faults, damage occurs to roads and railways, buildings, bridges and other engineering structures. However, well-constructed buildings rarely collapse completely. Usually the degree of destruction is directly dependent on the type of structure and the geological structure of the area. During earthquakes of moderate strength, partial damage to buildings can occur, and if they are poorly designed or poorly built, then their complete destruction is also possible.
With very strong tremors, structures built without taking seismic hazard into account can collapse and suffer severe damage. Usually one- and two-story buildings do not collapse, unless they have very heavy roofs. However, it happens that they are displaced from the foundations and often their plaster cracks and falls off.
Differentiated movements can cause bridges to move from their supports, and utilities and water pipes to burst. With intense vibrations, pipes laid in the ground can "fold", sticking into one another, or bend, coming to the surface, and deform railway rails. In seismically hazardous areas, structures should be designed and built in compliance with the building codes adopted for the given area in accordance with the seismic zoning map.
In densely populated areas, almost more damage than the earthquakes themselves are caused by fires resulting from the rupture of gas pipelines and power lines, overturning of stoves, stoves and various heating devices. Fighting fires is difficult due to the fact that the water supply is damaged, and the streets are impassable due to blockages.
1.5 Related phenomena
Sometimes tremors are accompanied by a clearly distinguishable low rumble, when the frequency of seismic vibrations lies in the range perceived by the human ear, sometimes such sounds are heard even in the absence of tremors. They are fairly common in some areas, although tangible earthquakes are very rare. There are also numerous reports of the appearance of a glow during strong earthquakes. There is no generally accepted explanation for such phenomena. Tsunamis (large sea waves) are caused by rapid vertical deformations of the sea floor during underwater earthquakes. Tsunamis propagate in the oceans within the deep-sea zones of the oceans at a speed of 400-800 km/h and can cause destruction on coasts thousands of kilometers away from the epicenter. Near the shores close to the epicenter, these waves sometimes reach a height of 30 m.
In many strong earthquakes, in addition to the main shocks, foreshocks (preceding earthquakes) and numerous aftershocks (earthquakes following the main shock) are recorded. Aftershocks are usually weaker than the main shock and may recur over weeks or even years, becoming less and less frequent.
6 Geographic distribution of earthquakes
Most earthquakes are concentrated in two extended, narrow zones. One of them frames the Pacific Ocean, and the second stretches from the Azores to the east to Southeast Asia.
The Pacific seismic zone runs along the western coast of South America. In Central America, it divides into two branches, one of which follows the West Indies island arc, and the other continues north, expanding within the United States, to the western ranges of the Rocky Mountains. Further, this zone passes through the Aleutian Islands to Kamchatka and then through the Japanese Islands, the Philippines, New Guinea and the islands of the southwestern part of the Pacific Ocean to New Zealand and Antarctica.
The second zone from the Azores extends east through the Alps and Turkey. In the south of Asia, it expands, and then narrows and changes direction to the meridional, follows through the territory of Myanmar, the islands of Sumatra and Java and connects with the circum-Pacific zone in the area of New Guinea.
There is also a smaller zone in the central part of the Atlantic Ocean, following along the Mid-Atlantic Ridge.
There are a number of areas where earthquakes occur quite frequently. These include East Africa, the Indian Ocean and in North America the St. Lawrence and northeastern United States.
1.7 Earthquake prediction
To improve the accuracy of earthquake prediction, it is necessary to better understand the mechanisms of stress accumulation in the Earth's crust, creep, and deformations on faults, to reveal the relationship between the heat flow from the Earth's interior and the spatial distribution of earthquakes, and to establish patterns of earthquake recurrence depending on their magnitude.
In many areas of the globe where there is a possibility of strong earthquakes, geodynamic observations are carried out in order to detect earthquake precursors, among which changes in seismic activity, deformation of the earth's crust, anomalies in geomagnetic fields and heat flow, sharp changes in the properties of rocks (electrical, seismic, etc.), geochemical anomalies, disturbances in the water regime, atmospheric phenomena, as well as anomalous behavior of insects and other animals (biological precursors). Such studies are carried out at special geodynamic testing grounds (for example, Parkfield in California, Garm in Tajikistan, etc.). Many seismic stations have been in operation since 1960, equipped with highly sensitive recording equipment and powerful computers, which make it possible to quickly process data and determine the position of earthquake sources.
2. Protective measures in case of threat and occurrence of earthquakes
Protective measures are reflected in action plans for the prevention and elimination of natural and man-made emergencies.
Such plans are developed at the territorial level, i.e. in the constituent entity of the Russian Federation, at the local level (in cities and districts) and in organizations.
The plans are approved by the heads of administrations of the corresponding level and, after approval, they become binding documents.
Short-term forecast data are the basis for taking emergency measures: warning and evacuation of the population, partial or complete.
Earthquake warning is the most important factor in reducing human losses.
The existing legislation in the field of protection against emergencies (FZ No. 68), article No. 11 "On the powers of the executive authorities of the constituent entities of the Russian Federation and local self-governments" imposes on the OIV and local self-government to ensure timely notification and informing the population about the threat or occurrence of emergencies (including and earthquakes).
As you know, such notification of the population of our region is carried out using the P-160 centralized notification system located at the control point of the GU GOChS region. In 2005-2007, it is planned to transfer the warning system to the new generation P-166 equipment. (from a memorandum on the implementation of the decisions of the joint meeting with the Minister of the Ministry of Emergency Situations on the issue "On measures to ensure the safety of the population and territories of the KO in conditions of increased seismic activity").
The Russian Federation has adopted a unified procedure for alerting the population about dangers, which provides for:
transmission of the sound signal "Attention everyone!" via radio and television channels and the subsequent transmission of speech information about the threat of an earthquake.
Voice information contains information about the danger and recommendations for the actions of the population.
Under the conditions of an earthquake, speech information may contain information about the strength, time, epicenter of the earthquake and recommendations for the actions of the population.
In order to protect the population, GOST R22.3.03-94 provides for a number of measures both at the stage of threat of danger and in conditions of immediate danger. The most effective way in case of an earthquake is the evacuation of the population (if there is a reliable forecast).
Under the conditions of an earthquake, evacuation has a number of features. (Guidelines for the evacuation of the population in emergency situations of natural and man-made nature. VNII GOChS Moscow. 1996).
From the earthquake-affected areas, in case of violation of the main life support systems, if necessary, the evacuation of the population is carried out.
In this case, the evacuation may be local or regional. The decision to carry out the evacuation of the population is made by the head of the administration of the subject of the Russian Federation or local self-government. Notification and informing the population about the procedure for conducting evacuation measures in case of failure of stationary elements of territorial warning systems, technical means is carried out using vehicles equipped with loud-speaking devices, as well as pre-made signs, banners and other visual information.
In the event of an earthquake, evacuation is carried out according to the production-territorial principle with the deployment of prefabricated evacuation centers in the affected areas. City squares, stadiums and other safe places are used as SEPs and places of temporary accommodation of the population.
The evacuated population will be housed in safe areas until further notice, depending on the situation. The homeless population can be temporarily accommodated in tents, cabin cars, prefabricated houses, railway cars. The decision to re-evacuate the population to places of permanent residence is made by the heads of the regional executive bodies of the constituent entities of the Russian Federation and local self-government bodies after the threat of new strong shocks and a thorough analysis of the situation at the POO and in the life support systems of the city has passed.
Elimination of the consequences of earthquakes is, according to Federal Law No. 68 "On the Protection of the Population ...", rescue and other urgent work (ASDNR) aimed at saving lives and preserving people's health, reducing damage to the environment and material losses, as well as localization of emergency zones, termination of the action of dangerous factors characteristic of them.
Since the nature of events during earthquakes is such that significant masses of people immediately find themselves in a direct threat to life and health, the conduct of ASDNR is of particular importance.
The decisive factor for the success of such works is the time factor. On the example of the Spitak earthquake (1988): of all those extracted on the first day, 31.5% were alive, and only 17.8% on the second.
For the organization of rescue operations, the structure of losses is of practical interest. The percentage of victims varies in a wide range - from 2.5 to 63.4%, while sanitary losses are more than irretrievable (3: 1 ratio).
With massive sanitary losses, 20% of the victims need first medical care, 20% are in extremely serious condition, 20% need anti-shock therapy, and 40% need outpatient treatment.
A characteristic feature of the consequences of earthquakes is the formation of blockages, i.e. a chaotic heap of building materials and structures, fragments of technological equipment, sanitary facilities, furniture, household utensils, stones, under which there may be victims who require immediate assistance.
Statistics show that within 3 hours after the start of the earthquake, it is possible to save 90% of the victims, after 6 hours this number is reduced to 50%, and after a few days there is practically no one to help.
Therefore, all the forces involved in the elimination of the consequences of earthquakes should be directed to the prompt conduct of search and rescue operations and the provision of medical assistance to the victims. In the absence of such assistance, the death toll is growing very rapidly.
Equally important, and sometimes decisive, in an earthquake are medical protection measures that are carried out at all stages of the ASDNR and include the provision of first medical, first medical and specialized assistance to victims, as well as anti-epidemic measures.
The latter, in the conditions of the destroyed life support systems of the population, are of particular importance.
Financing of measures to protect the population from the consequences of earthquakes is carried out in accordance with Federal Law No. 68
"On the protection of the population and territory from natural and man-made emergencies". The law establishes the procedure for financing targeted programs. Financing of measures to eliminate emergencies (including earthquakes) is carried out in accordance with the law at the expense of organizations located in emergency zones, federal executive authorities, relevant budgets, insurance funds and other sources.
In the absence or insufficiency of these funds, funds from the reserve fund of the Government of the Russian Federation may be allocated in the manner established by the Government of the Russian Federation.
Training of the population in actions in case of an earthquake is organized and carried out in accordance with the requirements of the Federal Law "On the protection of the population and territories from emergencies" No. 68-FZ and the Government Decree of 4.09.2003. No. 547 "On the preparation of the population in the field of protection against natural and man-made emergencies." The powers of the JIV and LSG include training the population in the field of protection. Such training is carried out in organizations, including educational institutions, as well as at the place of residence within the framework of existing training programs for various categories of the population, approved by the Minister of Emergency Situations.
Knowledge and skillful application by officials of the executive authorities of the constituent entities of the Russian Federation and local self-government bodies of a set of measures to protect the population will reduce the severity of the consequences in the conditions of possible earthquakes in the region.
earthquake magnitude protection population
3. Earthquake safety measures
If an earthquake caught you indoors, try to leave as soon as possible and be outside, preferably away from buildings.
When it is impossible to get out of the house for some reason (the stairs collapsed, the exit was blocked, etc.), take cover under the table or under the bed, or stand in the doorway, in the corner formed by the main walls.
You cannot use elevators, they can fail at any time, and you can get stuck in them.
Do not use matches, candles and lighters, as an explosion may occur due to gas leakage from destroyed and damaged communications.
If an earthquake catches you outdoors, stay away from houses, power lines, and generally from any fragile buildings that can collapse.
Do not take cover in basements, underpasses and tunnels. Roofs may collapse.
Earthquake rules:
Immediately turn off the electricity, gas, open the front doors.
Stop the crowd at the door.
Stop those who are going to jump from balconies and windows of floors higher than the first one.
Don't lose control of your kids.
If you are stuck:
Don't waste your energy on panic. Without water and food, you can hold out for a long time, but the first condition is fortitude.
Try to determine where you are, if there are other people nearby: listen, give a voice.
Remember that you can’t light a fire, that there is water in your toilet tank, that pipes and batteries are an opportunity to signal yourself. Look for clothes and blankets.
What to do after an earthquake?
Examine yourself and those around you - if you are injured.
Free those caught in easily removable blockages.
Reassure the children, the sick, the elderly.
Don't borrow the phone unless absolutely necessary - the stations will be overloaded.
Check plumbing, gas and electricity networks.
If during the first, most powerful push (5-40 seconds), for various reasons (sleep, panic, gatherings of children, etc.) you could not quickly leave the house (premises), carefully inspect your home. In the absence of external structural damage (cracks, skewed ceilings, ceilings, walls), you can stay at home and not go out. Subsequent (in a few hours) tremors will always be weaker.
List of used literature
1.http://www.krugosvet.ru/enc/Earth_sciences/geologiya/ZEMLETRYASENIYA.html?page=0,2, Encyclopedia Around the World, Earthquakes;
Http://www.kemsma.ru/GO/EQ-02.pdf, Protective measures in case of threat and occurrence of earthquakes;
Http://uznt42.ru/index.php?newsid=354, Earthquake safety measures.
Earthquake prediction is not perfect enough. It only allows one to guess where a major earthquake should be expected, and with some probability to determine the date when it will occur. In this regard, measures to protect against damage caused by earthquakes are urgently needed, which essentially boil down to two recommendations.
First, clearly dangerous areas should be avoided. Since a complete evacuation of places such as cities on the California coast is not possible, it is required to zone them on a large enough scale to minimize the risk.
Secondly, it is necessary to ensure the highest reliability of buildings in earthquake-prone areas. Absolutely anti-seismic buildings do not exist. But it is quite possible to design and build a building that is sufficiently resistant to earthquakes.
The anti-seismic properties of buildings can be identified based on the experience of past earthquakes. Perhaps the most unfortunate buildings for a seismic region are adobe and wooden houses with heavy stone roofs, which are so widespread in Asia and South America. Significant decorative loads in the upper part of buildings, including parapets on the upper floors, should be avoided. During the recent California earthquake, it was found that double garages on the ground floor also greatly reduced the strength of a home. Modern reinforced concrete buildings usually withstand earthquakes well, but there are no adequate engineering calculations for cases where the horizontal acceleration can be commensurate with the gravitational acceleration, as was observed during the California earthquake in 1971.
When constructing bold modern concrete structures in seismic areas, architects seem to have to inject a healthy conservatism into them and not forget about the material, the poor quality of which can play a fatal role in an earthquake. During the earthquake of 1930 in Italy, the cause of destruction was mainly the use of heavy rounded pebbles in construction, and during the earthquake in Skopje in 1963, many collapses were caused by poor bonding of concrete with unwashed aggregate. The fact that the buildings in Skopje "flattened out" also testifies to the weak reinforced concrete ceilings that lay on the unreinforced brick walls. A poor foundation is the key to possible destruction, whether it is insufficiently densely laid masonry or loose soil under buildings, as in Niigata in 1964.
If the building is constructed of high-quality reinforced concrete, has a steel frame, a deep foundation, a light roof and short chimneys, it will always show anti-seismic properties. It has been confirmed by many examples that, if we do not take into account the possibility of fires, the safest during an earthquake are wooden buildings - log huts and houses with a wooden frame. The Japanese came to the conclusion that corrugated steel or bitumen-impregnated cardboard rolls are a much better roofing material than ordinary tiles.
The Imperial Hotel, built in Tokyo just before the earthquake of 1923, was a building for that time, classical but in its earthquake-resistant design: the building had a deep foundation, tapered upwards and ended with a roof of light copper; a decorative pond was built in the center of the hotel, which saved it from a fire that arose after the earthquake.
Old buildings are especially troublesome during earthquakes. New homes are usually built to a certain standard, although this increases their cost. Demolishing old buildings and replacing them with new ones to ensure safety is too costly and requires a preliminary assessment of the damage that a strong earthquake can cause to a densely populated city. Even with highly skilled design, it is difficult to exclude the possibility of resonance in high-rise buildings, and slow seismic waves can accidentally coincide in period with the natural oscillations of the building.
Seismographs are installed in the Hokkaido (Japan) high-speed rail track, and the train will automatically stop if ground shaking exceeds a certain level. Even vaguely formulated earthquake forecasts can be used, for example, to make a decision to lower the water level in reservoirs and thereby increase the seismic stability of the site.
Unfortunately, many neglect such forecasts. Perhaps things are different in a controlled society. But in California, for example, recent studies have shown that an earthquake warning will only lead to half of the few who pay attention to it doing nothing at all, and the majority just starting to pray.
Taking into account all that has been said, the best protection against earthquakes should be considered the zoning of the territory and the identification of zones with different degrees of seismic hazard. In this case, the study of the geological specifics of the area is of paramount importance. Although in most earthquakes the greatest destruction is caused by ground motion, and not by its general displacement, the most important thing is to detect active faults that represent zones of obvious danger. Thus, the primary task in zoning seismic zones is to trace all available faults. This task is complicated by the fact that faults usually form rather wide bands with branches; moreover, over time, new faults may appear, and old, "stable" faults may shift.
The 1971 San Fernando earthquake originated on a fault that was thought to be inactive. Therefore, in geological mapping it is necessary to register all faults, regardless of their activity, and then - when populating the territory - to stay away from them. It is currently prohibited in California to build new buildings within 100 feet of a known fault, with the exception of small single-family homes that can be built within 50 feet of a fault. If the position of the fault is not precisely defined, they try to move the boundaries of the building as far as possible beyond the supposed fault zone. If, nevertheless, it is necessary to carry out construction in the active fault zone, they resort to various constructive tricks. So, in the aqueducts that supply water to Los Angeles, which cross the San Andreas Fault, there are mobile connections. It was gratifying to learn that plans to build a nuclear power plant on this fault (at Bodega Head) had recently been abandoned, although this required considerable pressure from environmentalists.
Undoubtedly, the most important criterion for zoning seismic zones for predicting earthquakes and preventing their consequences is taking into account the building properties of soils. The best in this regard are bedrocks, and the worst are unconsolidated, water-saturated young sedimentary deposits. The stronger the rock, the less potential damage from an earthquake. This relationship, although difficult to quantify, serves as the best guideline for identifying zones of relative safety. In unconsolidated strata, silts and sands with grains of the same size are the most susceptible to liquefaction, especially if these loose rocks are saturated with water and lie shallow. It has been established that the greatest amplification of seismic waves is observed in those areas where loose sediments lie directly on solid bedrock. Therefore, when planning for the expansion of cities such as Tokyo and San Francisco, the area distribution of different types of sediment should be considered.
The assessment of the possibility of flooding under the influence of a tsunami and taking into account the risk of occurrence and the scale of landslides associated with the movements of the earth's crust can also act as zoning criteria.
As already noted, the San Andreas Fault in California can be divided into active and fairly quiet sections. San Francisco and Los Angeles are located in potentially dangerous areas. But today there can be no talk of moving buildings, and even more so cities, to another place. The available information can only be used when planning new developments. The city of Valdez, destroyed in the 1964 Alaska earthquake, was rebuilt on bedrock, where it had previously been located on loose delta deposits. But in Managua (Nicaragua), it turned out to be almost impossible to avoid the development of “weak soils” that contributed to the destruction of the city during the earthquake of 1972. The city was restored to its original location. The only concession to nature was that the sections along the five faults that became active in 1972 were not built up.
Future
If such an earthquake, which hit San Francisco in 1906, is repeated, it could claim from two to one hundred thousand (and even more) human lives. This number will largely depend on the time of day, as well as the number of collapsed dams. There can be no doubt that San Francisco will experience at least one more earthquake: this city is located on one of the most active faults in the world, which will undoubtedly begin to move in the near future.
What is being done to prevent this threat? I will answer: depressingly little. This is due to the scale of the problem, which is difficult to control, as well as the indifference of the authorities. The material damage that could be caused to the city of San Francisco by a future earthquake will amount to many billions of dollars, even if we do not take into account the huge additional losses that will certainly be in the field of production. And yet, proper planning and calculation could greatly reduce these gigantic numbers. Recent studies have found that California could save $38 billion in material losses if $6 billion is now spent on reconstruction and resettlement. Is it worth investing so much to minimize the damage from some problematic natural disaster, which, moreover, does not know when it will happen? Putting on the scales a priceless treasure - human lives, we would get an unambiguous answer.
The geology of the San Andreas Fault System is well understood and we are able to pinpoint dangerous areas along the fault lines. But no one wants to take responsibility for taking appropriate action. There is a huge gap between the knowledge of specialists and the public assessment of the danger and cost-effectiveness of planning activities. An active fault line is undoubtedly the most immediate hazard zone in the event of any earthquake. California law currently prohibits construction along fault lines; it is recognized that in these territories it would be necessary to lay out parks, golf courses or even build highways (without building large bridges on them). But this was not always the case, and the mistakes of past years have not been corrected. Why do many buildings that are well known to be built on active faults continue to be exploited? Why do suburban areas west of San Francisco retain housing estates at two sites within the San Andreas Fault?
The situation is even worse in Oakland, on the inner side of the San Francisco Bay. Oakland is located on the Hayward Fault, a very active branch of the San Andreas system, where noticeable movements were observed during the strong earthquake of 1868. It is dangerous to build residential buildings on the fault, but it is even more dangerous to build public buildings there. And yet, Oakland is home to fourteen schools, two hospitals, and the UCLA campus football stadium on the Hayward Fault. Berkeley. The danger is well known, but due to inertia, carelessness and a number of other reasons, no attention is paid to it. The same is observed in Anchorage, Alaska. A 1959 USGS report pointed to the possible instability of the Bootlegger Cove Clay stratum during an earthquake. Nevertheless, houses were built on these clays within the Turnegain Heights plateau, and a school was erected on the Government Hill plateau. During the earthquake it all collapsed. How much then there was talk about the tragedy!
What will be the reaction of the population if the Hayward Fault begins to move under Oakland again and hundreds of people die under the rubble of two hospitals, fourteen schools and stadium stands?
mountain collapse
Mudflows
Landslides
Protection of the population during earthquakes
The main causes of death are:
· Destruction of buildings and structures and falling people under falling structures and blockages;
· Falling chimneys, cornices, balconies, individual parts of buildings, etc.;
· Falling broken glass;
· Hanging and falling broken electrical wires;
· Falling heavy objects in apartments;
· The fires are caused by gas leaks and electrical short circuits;
· Uncontrolled actions of people in case of panic;
In order to develop effective and competent actions, residents of earthquake-prone areas should do the following:
· Plan in advance an emergency plan and agree on a place for the family to gather after an earthquake;
· Make a list of telephones by which, in case of danger, you can call the civil defense service or other necessary;
· Regularly check the condition of electrical wiring, water supply and gas pipes;
· Prepare and store in advance in a place known to all family members: a battery-powered radio, a supply of canned and dry food for 3-5 days, a first aid kit with a double supply of dressings and medicines, a portable electric torch, a bucket of sand, a car fire extinguisher;
· Keep documents near the entrance to the apartment;
· It is advisable, where the documents are, to keep a backpack, in which there should be: a lantern, candles, hatchet, food;
· Cabinets, shelves, racks - tightly fasten to the floor and walls;
· Do not arrange shelves above sleeping places, front doors, toilets, sinks;
· Do not clutter up the entrance to the apartment with things;
· Close flammable containers tightly;
· Conduct evacuation drills;
· Determine in advance the safest places in the apartment, at work, etc., where you can wait out the shocks;
1911 - Pamir. Caused by an earthquake. Area: 2.5 billion km 2. The village of Kusoy was littered, the river was blocked, a mortgage of 300 meters appeared and a lake appeared at 53 km. With a depth of 6284 meters.
Landslide types:
· Grandiose (400 hectares and above);
· Large (100 - 400 ha);
· Medium (50 - 100 ha);
· Small (5 - 50 ha);
· Very small (up to 5 ha).
1922 - Alma-Ata. The mudflow speed was from 2 to 10 m/s. The mudflow width is determined by the long channel (3 - 100). Depth from 1.5 to 15 meters. Duration 1 - 3 hours, rarely up to 8 hours.
80% are related to the anthropological factor. Characterized by power:
· Large (up to 100 million m 3);
· Medium (up to 10 million m 3);
· Small (less than 10 m 3);
By scale:
· Huge (100 hectares or more);
· Large (50 - 100 ha);
· Medium (5 - 50 ha);
· Small (up to 5 ha);
Characterized by the number of dead, wounded, homeless, the number of settlements, the number of destroyed and damaged objects of the national economy, the area of flooding of agricultural elements.
1963 Italy. Landslide 240 million m 2 . Covered 5 cities. 3000 people.
1989 Checheno-Ingushetia. 82 settlements.
Causes of accidents and disasters:
· Violation of labor and technological discipline;
· Design errors;
· Errors during construction;
· Depreciation of equipment, buildings, structures;
· Natural disasters;
· Violations of a different nature;
Man-made emergency- a state in which, as a result of an accident or catastrophe, the normal conditions of life and activity of people are violated, there is a threat to their life and health. Damage is caused to the property of the population, the national economy and the environment.
For some reason, humanity believes that it has conquered nature, but this is just an illusion. Firstly, people know more about space than about the oceans. Secondly, scientists still cannot be predicted in advance. There are terrible consequences of earthquakes. Photos from the crash sites fly around the world every few years. It is appalling how insignificant man is before nature.
Earthquakes - causes and essence
We are used to the fact that the ground under our feet is something immovable and unshakable, but this is not at all the case. located in the earth's crust, are in constant motion, collide, diverge, crawl into each other and rub. In addition, mining in the bowels of the planet, explosions, landslides, filling reservoirs and many other artificial processes can also trigger large earthquakes. In fact, they are tremors and occur quite often - about once every 2 weeks.
However, most of them are on the ocean floor and have not too much power, so they are almost invisible. But if the epicenter is close enough to the surface and populated areas, and the intensity is high, the consequences can be catastrophic.
Seismologists Predictions
Protecting the population from the consequences of an earthquake begins with predicting its probability and calculating the time when it will occur. This is indispensable to the achievements of seismology, which has managed to develop some methods for predicting earth tremors of sufficient strength to affect people's lives.
The earthquake itself is preceded by some processes in the lithosphere, which can be traced and analyzed, which is what this science does. There are special devices - seismographs, which record the movements of tectonic plates. Their help in predicting strong earthquakes is invaluable, because they provide an opportunity to prepare for a disaster, gain a few hours so that they can begin evacuation and warn the population of the danger, which will reduce the number of victims.
The most seismic areas
The places where earthquakes occur are most often known, this is clear from the reasons for their occurrence. These are the joints of tectonic plates, which on the surface may look like young high mountains, for example, the Himalayas, the Andes, the Cordillera. In addition, there is a fault in the Far East, it runs from Kamchatka along Japan and stretches further - to the islands of Indonesia and New Zealand. The plate boundary also leaves Greece to the southeast, which carries a potential danger. And all this is not just curious knowledge. This allows you to build cities, large buildings, etc., taking into account such important information. And not only to apply special technologies, but also to be constantly on the alert, to be ready to cope with the elements. And this is not always easy, because the protection of the population from the consequences of an earthquake must be comprehensive. Ultimately, much depends on the scale of the disaster.
Consequences
If we take into account only strong and large earthquakes, the damage is obvious in their example. The shift of sections of the earth's crust in different directions provokes damage and destruction of buildings, roads and other objects. This can cause injury and death. That is why, in the first place, immediately after the disaster, all the forces of the rescuers are directed to such an event as protecting the population from the consequences of an earthquake.
The main damaging factors for this type are seismic waves of various types:
- Hypocentral longitudinal. They spread from the focus in all directions with the alternate formation of compression and tension zones. Ground displacement occurs along the direction of the waves. The speed is about 8 km/s.
- Hypocentral transverse. They also propagate in all directions at a speed of 5 km/s and form shear zones. The ground moves perpendicular to the direction.
- Rayleigh and Love waves. They spread from the epicenter to the upper layer of the earth's crust. There is a shift in the vertical and horizontal direction perpendicular to the waves. The speed is from 0.5 to 2 km/s.
In addition, the consequences of earthquakes for humans depend on the area in which they occur. They may be accompanied by avalanches, mudflows, floods, etc., depending on which natural and man-made objects have been damaged. Finally, the number of victims is also influenced by the actions of the population during an earthquake. If people know how to behave properly, they will not only survive themselves, but also help others.
Qualitative characteristics
Naturally, the magnitude and intensity of the impact also matter. For their assessment, several point systems used in different countries are used, respectively. In Russia, there are 12 levels:
- 1 point Registered only with the help of special devices.
- 2 points. Can be felt by sensitive animals and people on upper floors
- 3 points. Felt inside some buildings. The vibration is comparable to riding in a truck.
- 4 points. Felt by many people, doors and windows may sway.
- 5 points. Minor damage: swaying of hanging objects, shedding of whitewash, glass rattling.
- 6 points. There may be small cracks in the plaster, brickwork.
- 7 points. It is characterized by severe damage to buildings, the appearance of cracks in damp soils.
- 8 points. Serious damage to buildings, destruction of their elements.
- 9 points. Collapses in some buildings and landslides.
- 10 points. Destruction of many buildings. Cracks in the ground up to 1 meter wide.
- 11 points. Complete destruction of all buildings, numerous faults in the ground.
- 12 points. Catastrophic destruction and changes in the lithosphere. Deviations in the course of rivers.
Obviously, with an intensity of about 4-5 points and below, protection of the population from the consequences of earthquakes is not required, since they are minimal. Nevertheless, it is still worth knowing how to deal with disasters of this kind.
What to do?
Now that the causes and consequences of earthquakes have become clear, it’s worth talking about how to behave if the earth literally leaves from under your feet.
First of all, you need to try to pull yourself together and calm down - you need to act reasonably and soberly, without succumbing to panic. If the disaster caught on the street, you need to find a place away from the buildings and If the tremors began while staying in any room, the actions of the population during an earthquake depend on what kind of building it is. It is better to get out of a 2-3-storey house as quickly as possible, otherwise, if time permits, you need to open the door, which can then jam, and then find shelter. A place next to the main wall, away from the windows, is well suited, often a table under which you can hide under, or a bathtub, will often be an excellent option. The main thing is to stay away from loose heavy objects, windows, etc. Of course, if we are talking about transport, if shocks occur, you must immediately leave it.
Following actions
First of all, the protection of the population from the consequences of the earthquake consists in its emergency evacuation and the start of work to rescue those who may be under the rubble. It must be remembered that tremors can be repeated, aggravating destruction or causing new ones.
Russia, like any other rescue service, in such a disaster - to protect people. Rescuers provide first aid, lead the evacuation, clear the rubble. This applies not only to earthquakes, but also to any other emergency situations.
Preventive actions
A significant role is played by the measures that are taken even before the earthquake. This includes not only government funding of research and the work of seismologists, but also the construction of buildings, dams, and protective structures using special technologies.
People living in the danger zone are highly recommended to have a supply of food, water and medicines at home, to study the dwelling in advance for the most suitable place for shelter, and also to organize the possibility in any conditions, including in the absence of electricity, to receive information, for example, through battery operated radio. It is also worth making sure that all furniture, especially heavy ones, is in a stable state. It should be remembered that the protection of the population from the consequences of an earthquake primarily depends on the people themselves and their readiness to act quickly and correctly. So it will not be superfluous to conduct training events and trainings from time to time.
Major earthquakes in recent years
In the XXI century, there are 7 devastating disasters associated with the movement of tectonic plates. All of them were quite powerful and intense, had a significant magnitude and caused many thousands of victims and victims:
- 12/26/2003, Iran. Magnitude - 6.3. The death toll is estimated at 50-60 thousand people.
- 12/26/2004, Indian Ocean. Magnitude - 9.3. About 200-250 thousand victims.
- 05/12/2008, China, Sichuan province. Magnitude - 8.0. Up to 70 thousand dead.
- 01/12/2010, Haiti. Magnitude - 7.0. About 220 thousand people died, another 300 thousand were injured, more than 1 million lost their homes and property.
- 02/27/2010, Chile. Magnitude - 8.8. accompanied by a tsunami. Less than 1,000 were killed, and about 1.5 million houses were damaged.
- 03/11/2011, Japan. Magnitude - 9.0. Less than 15 thousand people died, about the same number went missing. The earthquake was accompanied by serious destruction, a tsunami.
- 25-26.04.2015, Nepal. Magnitude - 4.2-7.8. A series of earthquakes, as a result of which about 5 thousand died, another 7 were injured.
Not always the number of victims directly depends on the scale of the disaster. Often, reasonable actions of the population during an earthquake can save many lives. That is why informing people about how to behave in emergency situations must be constant and complete. This item is also included in the main tasks of the Russian Emergencies Ministry, but earthquakes on the territory of the Russian Federation are quite rare. Perhaps the neglect of this duty may one day cost great sacrifices.
All necessary activities are carried out in the following modes:
1. daily activities;
2. high readiness;
3. emergency.
I. Activities carried out in the mode of daily activities.
They include the following activities:
1. legal measures;
2. organizational;
3. engineering and technical.
1. Legal measures provided for in the Federal Law of December 21, 1994 No. 63-FZ "On the protection of the population and territories from natural and man-made emergencies."
The law defines a number of basic concepts. It defines such important concepts as the prevention of emergencies and the elimination of their consequences.
2. Organizational arrangements to protect the population and territories from earthquakes. Among them, the most important is the planning of protection and elimination of possible consequences of emergencies. The basis is seismic zoning, carried out in order to identify areas and areas where earthquakes can occur. Zoning is carried out on the basis of the analysis of seismic, geological and geographical data and long-term seismic observations.
In the future, maps highlight areas that are threatened by earthquakes of magnitude VII or more. In such areas, in relation to especially dangerous objects, special engineering and technical measures are envisaged. The organization of permanent control over the seismic situation consists in the behavior of seismic monitoring and the prediction of possible earthquakes. Earthquake forecasting is the most important event in the seismic situation control system, which allows timely measures to be taken to protect the population and territories, and to drastically reduce the costs of eliminating the consequences of earthquakes.
3. Engineering measures
These include: the construction of earthquake-resistant buildings and structures and the restriction of the construction of potentially dangerous facilities where earthquakes of intensity VII - IX points are possible (construction control).
Rational placement and dispersal of objects in the construction of cities and towns.
Development of special infrastructure for seismic areas. Construction of fire reservoirs in settlements; laying wide highways; construction of high strength bridges.
Carrying out engineering certification of individual potentially hazardous facilities, settlements and cities.
II. Events foreseeable in the mode of high alert for an earthquake.
The regime is introduced on the territory immediately after receiving an immediate earthquake forecast:
The population is notified through the media;
If necessary, evacuation is carried out or how to behave during shocks;
Rescue formations are put on alert;
Hazardous industries are transferred to emergency modes or stopped.
III. Events held in emergency mode.
With the beginning of the earthquake, the Commission for Emergency Situations introduces an emergency regime.
After the cessation of strong tremors, data on the situation in the affected area are collected and reported to the chairman of the CoES. Which makes a decision, and the authorities immediately bring it to the involved forces.
In order to organize and conduct rescue operations, the destruction zone is divided into regions, and the regions into work areas. Work leaders are appointed.
Necessarily and immediately transmitted information to a higher organization with data on the earthquake. If necessary, access of people to emergency zones is limited, reserves of material resources, emergency and public emergency rescue teams and volunteers from among the population are involved. Rescue work begins immediately, with all remaining forces.
How to survive an earthquake in the city:
1. Do not panic, act calmly and prudently.
2. When receiving a signal about an earthquake or at the first shocks, quickly move away from buildings.
3. On the street, move away from walls, poles, power lines.
4. In the building, stand in the doorways and corners of the main walls.
5. Beware of glass.
6. Safe place on the bathroom floor.
7. Do not use the elevator, go down the fire escape or downpipe.
8. After the tremors stop, leave the building, turn off the electricity, gas and water. Do not enter the building, aftershocks are possible.
