06.08.202327.05.2017

SEISMICITY OF THE TERRITORY OF RUSSIA

The territory of the Russian Federation, in comparison with other countries of the world located in seismically active regions, is generally characterized by moderate seismicity. The exceptions are the regions of the North Caucasus, southern Siberia and the Far East, where the intensity of seismic shaking reaches 8-9 and 9-10 points on the 12-point macroseismic scale MSK-64. Point 6-7 zones in the densely populated European part of the country also pose a certain threat.

Map of seismicity of the territory of Russia and adjacent regions.

To refer to:

Ulomov V.I. Seismicity // National Atlas of Russia. Volume 2. Nature. Ecology. 2004. pp. 56-57.
Ulomov V.I. Dynamics of the Earth's crust Central Asia and earthquake forecast. Monograph. Tashkent: FAN. 1974. 218 p. (you can download this book pdf_19Mb).

The first information about strong earthquakes in Russia can be found in historical documents of the 17th - 18th centuries. Systematic research into the geography and nature of seismic phenomena began at the end of the 19th and beginning of the 20th centuries. They are associated with the names of I.V. Mushketov and A.P. Orlov, who compiled the first catalog of earthquakes in the country in 1893 and showed that seismicity and mountain-forming processes have the same geodynamic nature.

A new era in the study of the nature and causes of earthquakes began with the work of Academician Prince B.B. Golitsyn, who laid the foundations of domestic seismology and seismometry in 1902. Thanks to the opening of the first seismic stations in Pulkovo, Baku, Irkutsk, Makeevka, Tashkent and Tiflis, more reliable information about seismic phenomena on the territory of the Russian Empire began to flow for the first time. Modern seismic monitoring of the territory of Russia and adjacent regions is carried out by the Geophysical Service of the Russian Academy of Sciences (GS RAS), created in 1994 and uniting over 300 seismic stations in the country.

Seismically, the territory of Russia belongs to Northern Eurasia, the seismicity of which is caused by the intense geodynamic interaction of several large lithospheric plates - the Eurasian, African, Arabian, Indo-Australian, Chinese, Pacific, North American and Sea of Okhotsk. The most mobile and, therefore, active plate boundaries are where large seismogenic orogenic belts are formed: the Alpine-Himalayan - in the southwest, the Trans-Asian - in the south, the Chersky belt - in the northeast and the Pacific belt - in the east of Northern Eurasia. Each of the belts is heterogeneous in structure, strength properties, seismic geodynamics and consists of uniquely structured seismically active regions.

In the European part of Russia, high seismicity is characterized North Caucasus, in Siberia - Altai, Sayan Mountains, Baikal and Transbaikalia, in the Far East - the Kuril-Kamchatka region and Sakhalin Island. The Verkhoyansk-Kolyma region, the regions of the Amur region, Primorye, Koryakia and Chukotka are less seismically active, although quite strong earthquakes occur here. Relatively low seismicity is observed on the plains of the East European, Scythian, West Siberian and East Siberian platforms. Along with local seismicity, strong earthquakes in neighboring foreign regions (Eastern Carpathians, Crimea, Caucasus, Central Asia, etc.) are also felt in Russia.

Feature all seismically active regions - their approximately the same length (about 3000 km), due to the size of ancient and modern subduction zones (immersion of the oceanic lithosphere into the upper mantle of the Earth), located along the periphery of the oceans, and their orogenic relics on the continents. The predominant number of earthquake foci are concentrated in the upper part of the earth's crust at depths of up to 15-20 km. The Kuril-Kamchatka subduction zone is characterized by the deepest (up to 650 km) sources. Earthquakes with intermediate focal depths (70-300 km) occur in the Eastern Carpathians (Romania, Vrancea zone, depth up to 150 km), in Central Asia (Afghanistan, Hindu Kush zone, depth up to 300 km), as well as under the Greater Caucasus and in the central part of the Caspian Sea (up to 100 km and deeper). The strongest of them are felt in Russia. Each region is characterized by a certain periodicity of earthquakes and the migration of seismic activity along fault zones. The dimensions (extent) of each of the sources determine the magnitude of the earthquakes (M, according to Richter). The length of rock ruptures in the foci of earthquakes with M=7.0 and higher reaches tens and hundreds of kilometers. The amplitude of displacements of the earth's surface is measured in meters.

It is convenient to consider the seismicity of the Russian territory by regions located in three main sectors - in the European part of the country, Siberia and the Far East. The degree of study of the seismicity of these territories, based not only on instrumental, but also on historical and geological information about earthquakes, is presented in the same sequence. The results of observations made only from the beginning of the 19th century are more or less comparable and reliable, which is reflected in the presentation below.

European part of Russia.

North Caucasus, being an integral part of the extended Crimea-Caucasus-Kopet Dag zone of the Iran-Caucasus-Anatolian seismically active region, is characterized by the highest seismicity in the European part of the country. Earthquakes with a magnitude of about M = 7.0 and a seismic effect in the epicentral region with an intensity of I 0 = 9 points and higher are known here. The most active is the eastern part of the North Caucasus - the territories of Dagestan, Chechnya, Ingushetia and North Ossetia. Of the major seismic events in Dagestan, the earthquakes of 1830 (M=6.3, I 0 =8-9 points) and 1971 (M=6.6, I 0 =8-9 points) are known; on the territory of Chechnya - the 1976 earthquake (M = 6.2, I 0 = 8-9 points). In the western part, near the border of Russia, the Teberda (1902, M=6.4, I 0 =7-8 points) and Chkhalta (1963, M=6.2, I 0 =9 points) earthquakes occurred.

The largest known earthquakes in the Caucasus, felt on the territory of Russia with an intensity of up to 5-6 points, occurred in Azerbaijan in 1902 (Shemakha, M = 6.9, I 0 = 8-9 points), in Armenia in 1988 (Spitak, M=7.0, I 0 =9-10 points), in Georgia in 1991 (Racha, M=6.9, I 0 =8-9 points) and in 1992 (Barisakho, M=6.3, I 0 =8 -9 points).

On the Scythian plate, local seismicity is associated with the Stavropol uplift, which partially covers Adygea, Stavropol and Krasnodar territories. The magnitudes of the earthquakes known here have not yet reached M = 6.5. In 1879, a strong Nizhnekuban earthquake occurred (M = 6.0, I 0 = 7-8 points). Available historical information about the catastrophic Ponticapaean earthquake (63 BC), which destroyed a number of cities on both sides of the Kerch Strait. Numerous strong and noticeable earthquakes were recorded in the area of Anapa, Novorossiysk, Sochi and other areas of the Black Sea coast, as well as in the Black and Caspian seas.

East European Plain and Urals are characterized by relatively weak seismicity and local earthquakes that rarely occur here with a magnitude of M = 5.5 or less, intensity up to I 0 = 6-7 points. Such phenomena are known in the area of the cities of Almetyevsk (1914, 1986), Elabuga (1851, 1989), Vyatka (1897), Syktyvkar (1939), Verkhniy Ustyug (1829). No less strong earthquakes occur in the Middle Urals, in the Cis-Urals, Volga region, in the region Sea of Azov and Voronezh region. Larger seismic events were also noted on the Kola Peninsula and the adjacent territory (White Sea, Kandalaksha, 1626, M = 6.3, I 0 = 8 points). Weak earthquakes (with I 0 = 5-6 points or less) are possible almost everywhere.

Scandinavian earthquakes are felt in northwestern Russia (Norway, 1817). In the Kaliningrad and Leningrad regions, weak local earthquakes also occur, caused by the ongoing post-glacial isostatic uplift of Scandinavia. In the south of the country, strong earthquakes are felt on the eastern coast of the Caspian Sea (Turkmenistan, Krasnovodsk, 1895, Nebitdag, 2000), the Caucasus (Spitak, Armenia, 1988), and the Crimea (Yalta, 1927). Over a vast area, including Moscow and St. Petersburg, seismic vibrations with an intensity of up to 3-4 points from the buried sources of large earthquakes occurring in the Eastern Carpathians (Romania, Vrancea zone, 1802, 1940, 1977, 1986, 1990) were repeatedly observed .). Seismic activity is often aggravated by technogenic impacts on the lithospheric shell of the Earth (extraction of oil, gas and other minerals, injection of fluids into faults, etc.). Such “induced” earthquakes are recorded in Tatarstan, Perm region and in other regions of the country.

Siberia.

Altai, including its Mongolian part, and Sayan Mountains- one of the most seismically active inland regions of the world. On the territory of Russia, the Eastern Sayan is characterized by fairly strong local earthquakes, where earthquakes with M of about 7.0 and I 0 of about 9 points are known (1800, 1829, 1839, 1950) and ancient geological traces (paleo-seismic dislocations) of larger seismic events were discovered. In Altai, the strongest of the recent earthquakes occurred on September 27, 2003 in the high-mountainous Kosh-Agach region (M = 7.5, I 0 = 9-10 points). Earthquakes of less significant magnitude (M = 6.0-6.6, I 0 = 8-9 points) occurred in the Russian Altai and Western Sayan before.

Crack above the source of the Gorno-Altai (Chuya) earthquake of September 27, 2003.

(in the photo, Doctor of Geological and Mineral Sciences Valery Imaev, Institute of the Earth's Crust SB RAS, Irkutsk).

The largest seismic disasters at the beginning of the last century took place in the Mongolian Altai. These include the Khangai earthquakes of July 9 and 23, 1905. The first of them, according to the definition of American seismologists B. Gutenberg and C. Richter, had a magnitude of M = 8.4, and the seismic effect in the epicentral region was I 0 = 11-12 points. The magnitude and seismic effect of the second earthquake, according to their estimates, are close to the maximum magnitudes and seismic effect - M = 8.7, I 0 = 11-12 points. Both earthquakes were felt across the vast territory of the Russian Empire, at distances of up to 2000 km from the epicenter. In Irkutsk, Tomsk, Yenisei provinces and throughout Transbaikalia, the intensity of shaking reached 6-7 points. Other strong earthquakes on the territory of Mongolia adjacent to Russia were the Mongol-Altai (1931, M = 8.0, I 0 = 10 points), Gobi-Altai (1957, M = 8.2, I 0 = 11 points) and Mogot ( 1967, M =7.8, I 0 =10-11 points).

Baikal rift zone - a unique seismic geodynamic region of the world. The lake basin is represented by three seismically active basins - southern, middle and northern. A similar zonation is also characteristic of seismicity east of the lake, right up to the river. Olekma. The Olekmo-Stanovoy seismically active zone to the east traces the boundary between the Eurasian and Chinese lithospheric plates (some researchers also identify an intermediate, smaller area, Amur plate). At the junction of the Baikal zone and the Eastern Sayan, traces of ancient earthquakes with M = 7.7 and higher (I 0 = 10-11 points) have been preserved. In 1862, during an earthquake of I 0 =10 magnitude in the northern part of the Selenga delta, a land area with an area of 200 km 2 with six uluses, in which 1,300 people lived, went under water, and Proval Bay was formed. Among the relatively recent large earthquakes are the Mondinskoe (1950, M=7.1, I 0 =9 points, the Muiskoe (1957, M=7.7, I 0 =10 points) and the Srednebaikalsky (1959, M=6.9, I 0 =9 points) As a result of the latter, the bottom in the middle basin of the lake dropped by 15-20 m.

Verkhoyansk-Kolyma region belongs to the Chersky belt, stretching in a southeast direction from the mouth of the river. Lena to the coast Sea of Okhotsk, Northern Kamchatka and Commander Islands. The strongest earthquakes known in Yakutia are the two Bulun earthquakes (1927, M = 6.8 and I 0 = 9 points each) in the lower reaches of the river. Lena and Artykskoe (1971, M=7.1, I 0 =9 points) - near the border of Yakutia with the Magadan region. Less significant seismic events with magnitudes up to M=5.5 and intensity I 0 =7 points or less were observed on the territory of the West Siberian Platform.

Arctic Rift Zone is a northwestern continuation of the seismically active structure of the Verkhoyansk-Kolyma region, extending in a narrow strip into the Arctic Ocean and connecting in the west with a similar rift zone of the Mid-Atlantic Ridge. On the shelf of the Laptev Sea in 1909 and 1964, two earthquakes with a magnitude of M = 6.8 occurred.

Far East.

Kuril-Kamchatka zone is a classic example of the subduction of the Pacific lithospheric plate under the continent. It stretches along the eastern coast of Kamchatka, the Kuril Islands and the island of Hokkaido. The largest earthquakes in Northern Eurasia with M greater than 8.0 and seismic effect I 0 =10 points and higher occur here. The structure of the zone is clearly visible from the location of the foci in plan and at depth. Its length along the arc is about 2500 km, its depth is over 650 km, its thickness is about 70 km, and the angle of inclination to the horizon is up to 50 degrees. The seismic effect on the earth's surface from deep sources is relatively low. Earthquakes associated with the activity of the Kamchatka volcanoes pose a certain seismic hazard (in 1827, during the eruption of the Avachinsky volcano, the intensity of shaking reached 6-7 points). The strongest (M = 8.0-8.5, I 0 = 10-11 points) earthquakes occur at a depth of up to 80 km in a relatively narrow strip between the oceanic trench, Kamchatka and the Kuril Islands (1737, 1780, 1792, 1841, 1918, 1923, 1952 , 1958, 1963, 1969, 1994, 1997, etc.). Most of them were accompanied by powerful tsunamis with a height of 10-15 m and higher. The most studied are the Shikotan (1994, M = 8.0, I 0 = 9-10 points) and Kronotskoe (1997, M = 7.9, I 0 = 9-10 points) earthquakes that occurred near the Southern Kuril Islands and the eastern coast of Kamchatka. The Shikotan earthquake was accompanied by a tsunami wave up to 10 m high, strong aftershocks and great destruction on the islands of Shikotan, Iturup and Kunashir. 12 people were killed and enormous material damage was caused.

Sakhalin represents the northern continuation of the Sakhalin-Japanese island arc and traces the boundary of the Sea of Okhotsk and Eurasian plates. Before the catastrophic Neftegorsk earthquake (1995, M=7.5, I 0 =9-10 points), the seismicity of the island seemed moderate and before its creation in 1991-1997. In the new set of maps of general seismic zoning of the territory of Russia (OSR-97), only earthquakes with an intensity of up to 6-7 points were expected here. The Neftegorsk earthquake was the most destructive earthquake ever known in Russia. More than 2000 people died. As a result, the workers' settlement of Neftegorsk was completely liquidated. It can be assumed that technogenic factors (uncontrolled pumping of petroleum products) played the role of a trigger for the elastic geodynamic stresses that had accumulated by this time in the region. The Moneron earthquake (1971, M=7.5), which occurred on the shelf 40 km southwest of Sakhalin Island, was felt on the coast with an intensity of up to 7 points. A major seismic event was the Uglegorsk earthquake (2000, M=7.1, I 0 about 9 points). Having arisen in the southern part of the island, far from populated areas, it caused virtually no damage, but confirmed the increased seismic danger of Sakhalin.

Amur region and Primorye characterized by moderate seismicity. Of the earthquakes known here, only one in the north of the Amur region has so far reached a magnitude of M = 7.0 (1967 I 0 = 9 points). In the future, the magnitude of potential earthquakes in the south of the Khabarovsk Territory may also be no less than M=7.0, and in the north of the Amur region earthquakes with M=7.5 and higher cannot be ruled out. Along with intracrustal earthquakes, deep-focus earthquakes in the southwestern part of the Kuril-Kamchatka subduction zone are felt in Primorye. Earthquakes on the shelf are often accompanied by tsunamis.

Chukotka and Koryak Highlands have not yet been sufficiently studied seismically due to the lack of the required number of seismic stations. In 1928, a swarm of strong earthquakes with magnitudes M=6.9, 6.3, 6.4 and 6.2 arose off the eastern coast of Chukotka. An earthquake with M=6.2 occurred there in 1996. The strongest previously known in the Koryak Highlands was the Khaili earthquake of 1991 (M = 7.0, I 0 = 8-9 points). Even more significant (M=7.8, I 0 =9-10 points ) the earthquake occurred in the Koryak Highlands on April 21, 2006. The villages of Tilichiki and Korf suffered the most, from where over five thousand residents of emergency houses were evacuated. Due to the sparse population, there were no deaths. Tremors were felt in the Olyutorsky and Karaginsky regions of Koryakia. As a result of the disaster, several villages were damaged.

Earthquake epicenters and aboutThe main seismically active regions of Northern Eurasia:

1. - European part of Russia; 2. - Central Asia; 3 - Siberia; 4. - Far East. Below, in the form of vertical elevations, the ratio of the average annual number of earthquakes in these regions is shown. As you can see, Central Asia comes in second place in terms of seismic activity, after the Kuril Islands and Kamchatka.

Network of seismic stations of the Geophysical Survey of Russia as of 2004

The regions for which the processing centers of the GS RAS indicated on the map are responsible are outlined.

Literature.

V.I.Ulomov. Seismicity // Great Russian Encyclopedia (BRE). Volume "Russia". 2004. pp. 34-39.

Seismicity and seismic zoning of Northern Eurasia (Ed. V.I. Ulomov). Volume 1. M.: IPE RAS. 1993. 303 p. and Volume 2-3. M.: OIPZ RAS. 1995. 490 p.

Earthquakes in Russia in 2004. - Obninsk: GS RAS, 2007. - 140 p.

From the newspaper "Construction Expert", December 1998, No. 23

"...Particularly acute problems associated with the reliability of houses arise during construction in areas with increased seismic activity. For Russia, these are the Far East and the North Caucasus. For many CIS countries, seismic areas are their entire territory or a significant part of it.

It is, of course, impossible to take all individual construction under qualified control. Another way is to create very attractive construction technologies that make it possible, in any conditions, to ensure a high margin of reliability of the buildings being constructed with comfortable living in them... TISE can be classified as such a technology...”

We are interested in the nature of earthquakes, their physical parameters and the degree of influence on structures.

The main causes of earthquakes are the movements of blocks and plates of the earth's crust. Essentially, the Earth's crust is plates floating on the surface of a liquid magma sphere. Tidal phenomena caused by the attraction of the Moon and the Sun disturb these plates, causing high stresses to accumulate along the lines of their junction. Reaching a critical value, these stresses are released in the form of earthquakes. If the source of the earthquake is on the continent, then severe destruction occurs in and around the epicenter, but if the epicenter is in the ocean, then crustal movements cause a tsunami. In the zone of great depths this is a barely noticeable wave. Near the shore, its height can reach tens of meters!

Often the cause of ground vibrations can be local landslides, mudflows, man-made failures caused by the creation of cavities (mining workings, water intake from artesian wells...).

Russia has adopted a 12-point scale for assessing the strength of an earthquake. The main feature here is the degree of damage to buildings and structures. The zoning of the territory of Russia according to the point principle is given in building codes (SNiP 11-7-81).

Almost 20% of the territory of our country is located in seismically dangerous zones with earthquake intensity of 6-9 points and 50% are subject to 7-9 magnitude earthquakes.

Taking into account the fact that TISE technology is of interest not only in Russia, but also in the CIS countries, we present a map of the zoning of Russia and neighboring countries located in seismically active zones (Figure 181).

Figure 181. Map of seismic zoning of Russia and neighboring countries

The following seismically dangerous zones are distinguished on the territory of our country: the Caucasus, Sayan Mountains, Altai, Baikal region, Verkhoyansk, Sakhalin and Primorye, Chukotka and the Koryak Highlands.

Construction in seismically hazardous zones requires the use of structures of increased strength, rigidity and stability, which causes an increase in construction costs in a 7-point zone by 5%, in an 8-point zone by 8%, and in a 9-point zone by 10%.

Some features of seismic loads of building elements:

– during an earthquake, the building is exposed to several types of waves: longitudinal, transverse and surface;

– the greatest destruction is caused by horizontal vibrations of the earth, with which the destructive loads are inertial in nature;

– the most characteristic periods of soil vibrations lie in the range of 0.1 – 1.5 seconds;

– maximum accelerations are 0.05 – 0.4 g, with the highest accelerations occurring in periods of 0.1 – 0.5 seconds, which correspond to minimum vibration amplitudes (about 1 cm) and maximum destruction of buildings;

– a long period of oscillations corresponds to the minimum accelerations and maximum amplitudes of soil vibrations;

– reducing the weight of the structure leads to a reduction in inertial loads;

– vertical reinforcement of building walls is advisable in the presence of horizontal load-bearing layers in the form of, for example, reinforced concrete floors;

– seismic insulation of buildings is the most promising way to increase their seismic resistance.

This is interesting

The idea of seismic insulation of buildings and structures arose in ancient times. During archaeological excavations in Central Asia, reed mats were discovered under the walls of Heck's buildings. Similar designs were used in India. It is known that the earthquake of 1897 in the Shillong region destroyed almost all the stone buildings, except those built on seismic shock absorbers, albeit of a primitive design.

The construction of buildings and structures in seismically active regions requires complex engineering calculations. Earthquake-resistant buildings erected using industrial methods undergo deep and comprehensive studies and complex calculations involving a large number of specialists. Such expensive methods are not available to an individual developer who decides to build his own house.

TISE technology offers an increase in the seismic resistance of buildings erected under individual construction conditions in three directions at once: reducing inertial loads, increasing the rigidity and strength of walls, as well as introducing a seismic isolation mechanism.

The high degree of hollowness of the walls makes it possible to significantly reduce the inertial loads on the building, and the presence of through vertical voids makes it possible to introduce vertical reinforcement that is organically integrated into the structure of the walls themselves. Using other individual construction technologies, this is quite difficult to achieve.

The seismic isolation mechanism is a columnar strip foundation built using TISE technology.

A carbon steel rod with a diameter of 20 mm, which passes through the grillage, is used as vertical reinforcement for the foundation column. The rod has a smooth surface covered with tar. At the bottom it is equipped with an ending embedded in the body of the post, and at the top with an ending protruding from the grillage and equipped with an M20 thread for a nut (RF patent No. 2221112 of 2002). The support itself is included in the grillage array by 4...6 cm (Figure 182, a).

After concreting, three or four cavities 0.6...0.8 m deep are made around each of the supports with the same foundation drill and filled with either sand, or a mixture of sand and expanded clay, or slag. In sandy soil such cavities need not be made.

Figure 182. Seismic isolating foundation with a central rod:
A – neutral position of the foundation support; B – deflected position of the foundation support;
1 – support; 2 – rod; 3 – lower end; 4 – nuts; 5 – grillage; 6 – cavity with sand; 7 – blind area; 8 – directions of ground vibrations

Upon completion of construction, the rod nuts are tightened with a torque wrench. This creates an “elastic” hinge in the area where the pillar meets the grillage.

During horizontal vibrations of the soil, the pillars deviate relative to the elastic hinge, the rod stretches, while the grillage with the building remains motionless by inertia (Figure 182, b). The elasticity of the soil and rods returns the pillars to their original vertical position. During the entire life of the building, free access to the pole reinforcement tensioning units must be provided both along the outer perimeter of the house and under the internal load-bearing walls. After completion of construction and after significant seismic vibrations, the tightening of all nuts is restored with a torque wrench (M = 40 - 70 kg/m). This version of the Seismic Isolating Foundation can be considered to some extent industrial, since it includes rods and nuts, which are easier to produce in production.

TISE technology provides for the implementation of seismic isolating supports in a more democratic way, accessible to developers with limited production capabilities. As a reinforcing elastic element, two brackets from a reinforcement bar with a diameter of 12 mm with bent ends are used (Figure 183). The middle part of the reinforcement branches over a length of about 1 m is lubricated with tar or bitumen (at an equal distance from the edges) to prevent adhesion of the reinforcement to the concrete. During seismic vibrations of the soil, the reinforcement bars in their middle part stretch. With horizontal soil displacements of 5 cm, the reinforcement stretches by 3...4 mm. With a tensile zone length of 1 m, stresses of 60...80 kg/mm² arise in the reinforcement, which lies in the zone of elastic deformations of the reinforcement material.

Figure 183. Seismic isolating foundation with reinforcement brackets:
1 – support; 2 – bracket; 3 – grillage; 4 – cavity with sand

When building a house in seismically active zones, waterproofing is not done at the connection between the grillage and the walls (to prevent their relative displacement). Using TISE technology, waterproofing is performed at the junction of the grillage with the foundation pillars (two layers of roofing material on bitumen mastic).

When constructing adjacent structures, porches, blind area elements, etc., you should constantly pay attention to ensure that the foundation strip does not touch them with its side surface. The gap between them should be at least 4 - 6 cm. If necessary, such contact is allowed (with the porch, the frame of light panel extensions, verandas) from the consideration that after destruction by an earthquake they will be restored.

This is not the foundation, but...

When building in seismically active areas, the use of roofing made of clay or sand concrete tiles must be justified.

Many Japanese individually built houses with a light frame are covered with high-quality clay tiles. In conditions of dense Japanese buildings, such houses can withstand typhoons well. However, during an earthquake under the weight tiled roof the house collapses, burying the inhabitants under its enormous weight.

Currently, many “light” roofing materials that closely imitate tiles have appeared on the construction market. Light roofing means minimal inertial loads for connecting the roof to the walls and preventing the roof from collapsing due to its excess weight.

As you already know, most city residents live in three main types of houses: small-block, large-block, large-panel. Frame-panel buildings are, as a rule, public and administrative. Let's try to imagine an earthquake situation for each of these houses.

So, you are in a small block house. The seismicity deficit of such an unfortified house is 1.5-2 points. We only note that cracks in internal and external walls can range from hairline to 3-4 centimeters. A commission of specialists observed cracks of this size, through which the street was visible, in similar houses in the city of Leninakan after the Spitak earthquake. There is no need to panic at the sight of such violations, because the house is designed for this. You should be especially careful if the damage is very different from what we have described. For example, there will be a shift of ceilings from the walls by 3 or more centimeters. rice. 5 What elements of the house best withstand the elements?

Let us turn to Figure 5, which shows the most typical layout of a residential 2-5-story small-block building. Load-bearing (on which the floors rest) main walls 1,2 are damaged less than transverse walls 3,4,5. The latter are easier to move (cut) by horizontal seismic forces, since they are less loaded. End wall 4, which is connected to the other walls on only one side, is considered especially dangerous. Sometimes the ends of buildings even come off the building and fall out, which was repeatedly observed in the village of Gazli, the cities of Spitak and Neftegorsk. The corner of building 6, which is least connected to the building and is most susceptible to “loosening” during an earthquake, is very dangerous. Already with a 7-8 magnitude earthquake, the corners of buildings on the top floor are usually damaged, and with a 9-magnitude earthquake they can fall out. It is not recommended to be near the external longitudinal walls (1) during an earthquake, since glass can “shoot out” here, windows can fall in and out (this remark is true not only for small-block houses), and in particularly weak houses they can even tear off (longitudinal walls from transverse ones) ). The safest places during an earthquake are the intersections of internal load-bearing longitudinal walls (2) with internal transverse ones. The figure shows the most typical “safety islands”: at the exits from apartments to the staircase and at the intersection wall 5. In these places, due to the cross-shaped intersection of load-bearing and non-load-bearing walls, a core of increased strength is created, which can withstand even the collapse of other walls. This core is stronger the fewer doorways it contains. So, for example, the most reliable place will be at the right three-room apartment in the area of the intersection of internal walls 2 and 5. Also reliable seems to be an island in a two-room apartment at the intersection of blind sections of walls type 3 and 2. As for the one-room and left three-room apartments, they have cores They have one or two openings and are therefore considered less durable than cores with blank walls. Therefore, if necessary, you can move here along wall 2. In such houses, built in the 70-80s. the doorways opening onto the staircase are framed with reinforced concrete frames, which guarantees their strength. However, in houses of earlier construction there are not frames everywhere, so these exits cannot be considered completely safe. Some general tips on behavior. As soon as an earthquake begins, you should open the doors leading to the landing and go to the traffic island. It's worth trying to run out of the building if you're on the first or second floor. From a higher floor, you may not be able to do this before serious damage begins. You need to run out of the house especially quickly and carefully so that you are not “covered” by bricks flying from the roof from destroyed pipes, or crushed by a heavy canopy. If you did not make it to the traffic island, you should remember that partitions made of small block masonry are very dangerous. They are among the first to be destroyed, even to the point of collapse. Wooden panel partitions are less dangerous, but quite large pieces of plaster can fall off from them, which are especially dangerous for small children. It is easy to distinguish a stone partition from a panel partition by the dull, very short, non-vibrating sound when hitting the wall with a fist. When arranging furniture in the apartment, make sure that bulky furniture cannot fall onto the safety island or onto a possible escape route from the apartment.

Many residents of big block homes know that their homes can withstand earthquakes quite well. Their actual seismic resistance is estimated by experts at 7.7 points.

In Fig. Figure 6 shows a typical layout of a large-block house. The position of the main load-bearing and non-load-bearing walls is the same as in a small-block house. A large-block house loses its load-bearing capacity mainly due to the separation of the walls into separate blocks, which in old-built houses, unfortunately, do not have a good connection with each other. The external walls consist of two blocks according to the height of the floor: a wall with a height of 2.2 m and a lintel with a height of 0.6 m. The internal walls consist of blocks with a floor height, i.e. 2.8 m. Reinforced concrete floors with a thickness of 0.22 m are supported on the lintel blocks of external walls and directly on the blocks of internal walls. During an earthquake with a magnitude greater than 7, the blocks begin to shift out of the plane of the wall. The greatest cracks and damage to joints (11) should be expected in non-load-bearing transverse walls that are less loaded with slabs, especially in the end wall (4) and staircase walls (3). In the last walls there is a small connection between the blocks with the help of not very strong metal plates, which even during an earthquake of 7.5-8 points will begin to become very loose, breaking off pieces of concrete and plaster around them. These debris can injure people running up the stairs, so it is necessary to move closer to the railings. rice. 6. As in small-block buildings, the corners of the building are very dangerous (6), especially on the upper floors. Shift of blocks from the plane of the wall can lead to partial collapse of the end wall (4) and floor slabs. The partitions in these houses, as a rule, are wooden, panel, plastered, and you should not be afraid of their collapse. Injury, especially to a small child, can be caused by pieces of plaster falling off the partitions and pieces of cement mortar falling out of the seams between the floor slabs. Such damage occurs during an earthquake of magnitude 7.5. The figure shows the safest places in a large-block house. Unlike small-block buildings, here all the exit doors to the staircase landing are reinforced with reinforced concrete frames (9), so the likelihood of the doors jamming due to misalignment is low and the exit from the apartment is quite reliable. To the general advice - do not hang heavy shelves in the area of the safety island and secure furniture, it should be added that this is especially important to do in the pantry closet (7) and in the corridor (8), otherwise there will simply be no room left for you on the safety island.

In old large-panel five-story residential buildings, the typical layout of which is shown in Fig. 7, the area of the traffic islands is already much larger. Despite the fact that these houses were designed for 7-8 points, practice has shown that their actual seismic resistance is close to 9 points. Not a single such building was destroyed anywhere during earthquakes in the territory of the former Soviet Union. All external and internal walls in such houses are large reinforced concrete panels, well connected at the nodes using embedding and welding (node 5). Internal walls and partitions are connected to each other using welded outlets. The floor panels are the size of a room, rest on the walls on four sides and are also connected to the walls by welding. The result is a reliable honeycomb structure. Calculations of the behavior of a large-panel house during a 9-magnitude earthquake showed that the greatest damage is expected in the corners of the building (6), and in the junctions of the end panels (4), where large vertical cracks of 1-2 cm can open. The first cracks may appear already at L-7.5 points. The same cracks may appear at expansion joints between buildings. But these cracks do not affect the overall stability of the building. Unpleasant factors include the possible appearance of inclined cracks up to 1 cm wide in reinforced concrete lintels above the entrance doors to apartments, which can lead to jamming of the doors. Therefore, they must be closed immediately when vibrations begin with a force of 6 points or more. Since large-panel buildings are quite reliable, you should not run out of them during an earthquake. But during an earthquake, it is recommended to stay in the area of safety islands, away from the outer walls, where window panes can “shoot out,” and from the end wall, in the nodes of which long, frightening cracks may open. You should not run out also because in the old houses of this series there are very heavy, dangerous canopies over the entrances to the entrances. Embedded metal parts with which these canopies were attached to the building. due to aging, they are heavily rusted and may not hold them up during strong seismic shocks.

During the earthquake on the island. In Shikotan in 1994, several canopies fell near similar large-panel three-story houses, which crushed two residents who were running out of one house. However, not a single person remaining in the house was injured. The house itself received no serious damage. Later large-panel houses, the so-called “improved” series, with bay windows, as well as houses of a “new” layout with large glazed balconies, were initially designed for 9 points and it is practically safe to be in them during an earthquake of such force. You need to beware of broken glass falling from above, especially from balconies, which can fly over long distances - up to 15 meters. Therefore, it is not recommended to run out of these houses, as well as to be on the street next to them. Fig. 7 Experience shows that even with strong 8-9 magnitude earthquakes, 1-2-story wooden houses practically do not collapse until they collapse. One of the authors of the book observed the behavior of panel and block houses during a 9-magnitude earthquake on the island. Shikotane. Of the nearly fifty two-story houses surveyed, there was not a single house where at least one wall had collapsed or the ceiling had failed. There were cases when the foundation “teared out” from under the house and was carried away by a landslide of 1-1.5 meters, and the house, sagging, stood! There were breaks in the walls in the corners of up to 20 cm and subsidence of the ground under the building up to 0.5 m, but the houses survived. Therefore, you should not run out of such houses, especially since bricks falling on those running out from collapsing chimneys pose a danger. In wooden houses, ceilings sway more than others and walls “crack”, which causes unpleasant sensations. Pieces of plaster may fall out of the walls and ceiling. Therefore, in such houses it makes sense to choose a place where the plaster fits tightly to the wall or ceiling, that is, it does not “bounce” in advance when tapped. It is better for children to hide under the table. And, of course, you need to stay away from external walls with windows, from heavy cabinets and shelves, especially if they are not specially secured. This is a general rule for any building.

Home training. Let's do a thought experiment. Close your eyes and imagine lying in your own bed. Imagine that at this moment the first strong seismic shock has occurred. Now mentally try to get to the door as quickly as possible, open it and take a place in the doorway. At the same time, bend your fingers in each case when, during your mental progress, you come across obstacles that actually exist. Now do the math. Each obstacle is at least 3 lost seconds. Estimate the time of pure movement and the time of opening the door lock. Add a few seconds to grab your backpack with documents and groceries (of course, it hangs next to the door, as recommended). And if you get more than 20 seconds, then give yourself a fat FAIL and let's get down to reorganization. Make a list of obstacles discovered during the experiment. This is the minimum that needs to be done. Let's start moving in reverse order. Evaluate the door lock in terms of its ability to quickly open the door. Is it easy for you to find the lock itself and its opening device even in the dark? How many steps are required to unlock the lock and door? Try to arrange everything in such a way that the lock opens with a minimum of movements, and bring these movements to automaticity. Inspect the area around the front door. Are there objects nearby that, at the first push, could fall and block your path? If there are any, either strengthen them or find a more suitable place for them in the apartment. The corridor should be as free as possible. Very often, the passage is cluttered with things that have only recently been brought into the apartment and have not yet found their permanent place. Everyone knows that there is nothing more permanent than temporary. Therefore, without delaying “for later,” clear the path to salvation for yourself. Make sure that there are no objects along the walls that could be caught on. Look at your feet to see if shoes that are not currently in use have been removed from the corridor and if they are not creating obstacles to movement. Now let's turn our attention to the door from the corridor to the room. It is advisable that it be constantly open. Think about how you can lock it in the open position and install a latch. If there is carpet on the floor or there are tracks, then check how tightly they fit to the floor, whether there are any gathers, folds, or burrs. Does the track slip on the main floor covering? Pay special attention to the joints of carpets and paths. Eliminate all flaws, let the path be “silk”. In recent years, mobile interior elements have firmly entered our everyday life: tables on wheels, mobile TV stands, video and audio equipment. Make it a rule not to leave them in the evening along a possible escape route. Leave them in such a position that their spontaneous movement in the event of seismic shocks cannot occur in the direction of this escape route and does not cause objects or furniture to fall onto this route. If you use extension cords to connect electrical equipment, make sure that the wires do not cross the path of your movement to the outlet. The pride of almost every family is its home library. Check whether books are on open shelves, from which they could fall at your feet at the first seismic shock or fall on your head when you run to the door. Evaluate items on open shelves from the same perspective, especially if these shelves are located above the doors. Make sure the shelves themselves are secured securely. Bedside tables should also be securely fastened so as not to be the first insurmountable barrier to salvation. It is advisable to fix the table lamps standing on these cabinets. If the drawers in these bedside tables easily fall out or open when the door is gently pushed, then make sure that they are securely fixed. Clothes that periodically accumulate next to the bed can be a serious obstacle to rapid movement. Make it a rule to put away things that you will not wear that day. (It turns out that a possible strong earthquake is an important reason to keep your house in order!)

Think back to the thought experiment you conducted and pay attention to which obstacle came your way first. If it is resolved, check to see if there are still unresolved barriers on your post-experiment list and take appropriate action. Now check the exit path for each family member. If there are small children in the family and you will move towards them first, then pay attention to those areas that you will have to cross twice in different directions. Find out if your first movement will create obstacles to the return journey. Similarly, inspect and arrange the escape route from the living room and kitchen. Please note that several people, including children, can move from these rooms at the same time. When you watch athletics competitions, while watching a steeplechase race, you often have a desire to make the path easier for the athletes and remove obstacles and a pit of water. How easily and beautifully they would reach the finish line. But the rules of the game there do not allow this. The seismic safety rules, on the contrary, tell us - don’t let things get to the point of a home steeplechase, otherwise you won’t be able to get to the finish line safely. Therefore, we advise you to remove barriers from the road and not take unnecessary risks.

Excerpt from the work of V.N. Andreeva, V.N. Medvedev “SEISMIC RISK PROBLEMS IN THE REPUBLIC OF SAKHA (YAKUTIA)” without author’s illustrations.

Killer houses on the disaster map

An alarming trend has been identified newest Maps general seismic zoning of the territory of the Russian Federation: compared with previous calculations, the number of regions with increased seismic hazard has increased significantly.

The planet continues to show its violent character. Earthquakes occur there with amazing regularity. In just two weeks there were 15 of them - in Turkey and Mexico, Sakhalin and Kamchatka, Los Angeles and Alaska, the Caucasus and Taiwan, the Ionian Sea and Japan. Fortunately, this time the tremors were not the strongest - their maximum intensity did not exceed 6.2 points, but they also led to destruction and loss of life. But a strong earthquake can become an economic and social disaster for an entire country; just remember the tragedy in India on January 26 last year.
In recent decades, the danger of seismic disasters has increased sharply, which is primarily due to human economic activity, technogenic impacts on the earth’s crust - the creation of reservoirs, the extraction of oil, gas, solid minerals, the injection of liquid industrial waste and a number of other factors. And the possible destruction of large engineering structures built on the surface (nuclear power plants, chemical plants, high-rise dams, etc.) can lead to environmental disasters. An example of such a potential danger is the Balakovo Nuclear Power Plant, which can withstand an earthquake no stronger than magnitude 6, despite the fact that the Saratov region today is classified as a zone of magnitude seven seismicity.
Almost no strong underground shock passes without leaving a trace: after each, the expected seismic hazard in the affected and adjacent regions increases. For example, the earthquake in Neftegorsk in 1995 was assessed by experts as 9-10 points. But back in the 60s, this and the surrounding areas were not considered seismically dangerous at all, and the possibility of earthquakes was not taken into account when designing buildings. The same underestimated forecasts of seismic activity were made in Japan, China, Greece and other countries. Unfortunately, similar errors cannot be ruled out in the future.
So the sad list of regions where the earth can suddenly stand on end is constantly growing. The latest Maps of general seismic zoning of the territory of the Russian Federation clearly demonstrate this. Until recently, two regions of Russia were considered the most seismically dangerous - Sakhalin, Kamchatka, the Kuril Islands and other areas of the Far East, as well as the territories Eastern Siberia, adjacent to the Baikal region and Transbaikalia, including the Altai Mountains. Catastrophic earthquakes with an intensity of 9 or more are possible there (up to 8.5 on the Richter scale). By the way, the territory of the Sakhalin region is among the most earthquake-prone not only in Russia, but also in the world.
Now, on the latest maps, the threat of earthquakes of magnitude 9 or more has spread to a significant part of the North Caucasus, where about 7 million people live. And this despite the fact that until recently the construction of residential buildings and industrial buildings was carried out here taking into account seismicity of 7 points. The greatest concern is Krasnodar region with a population of five million. In the summer months, on a narrow strip of the Black Sea coast, the number of people increases many times over.
Another very important difference between the new maps is that zones of magnitude 10 earthquakes appeared on them for the first time. They are located in Sakhalin, Kamchatka and Altai. Previously, such areas did not exist in our country.
But the exact location, strength and time of the earthquake is impossible to predict. There are no ways to prevent a cataclysm. The main task is to minimize destruction and loss of life. The latest strong earthquakes in Neftegorsk (1995), Turkey and Taiwan (1999) showed that fundamentally new approaches are needed in the regulation and design of engineering structures.

In the meantime, experts are coming to shocking results: the main “killers” of people during earthquakes are two types of buildings. And the most common ones. First of all, houses with walls made of low-strength materials. The second type is reinforced concrete frame buildings, the massive destruction of which was completely unexpected, since until recently they were one of the first places in terms of seismic resistance. Thus, during the earthquake in Leninakan, 98 percent of reinforced concrete frame houses collapsed like an accordion, and more than 10 thousand people died in them.

In contrast to frame buildings, large-panel buildings and houses with walls made of monolithic reinforced concrete, which have maximum rigidity in all directions, have proven themselves very well.
Of course, a radical solution to the current situation: the demolition of all dangerous houses and the construction of new ones in their place is unrealistic today. Therefore, the most difficult and urgent task is to strengthen buildings built without taking into account possible seismic effects or designed for minor earthquakes. Unfortunately, in Russia this problem is extremely acute. It is not for nothing that in the Federal Target Program “Seismic Safety of the Territory of Russia”, which began to operate this year, there is a terrible phrase: “In the entire history of the USSR and the Russian Federation, national seismic safety programs have not been implemented in the country, as a result of which tens of millions of people live in earthquake-prone areas in houses characterized by a seismic resistance deficiency of 2-3 points.” At the same time, in a number of constituent entities of the Russian Federation, even according to rough estimates, from 60 to 90 percent of buildings and other structures should be classified as non-seismic resistant.
According to the Program, more than half of the territory of Russia may be affected by earthquakes of medium magnitude, which can lead to severe consequences in densely populated areas, and “about 25 percent of the territory of the Russian Federation with a population of more than 20 million people may be subject to earthquakes of magnitude 7 or higher.
It is precisely taking into account the high seismic hazard, population density, and the degree of actual seismic vulnerability of buildings that the constituent entities of the Russian Federation were classified depending on the seismic risk index and divided into 2 groups.
The first group (see table) included 11 constituent entities of the Russian Federation - regions of the highest seismic risk. Many cities and large settlements in these regions are located in areas with seismicity of 9 and 10 points.
The second group included Altai, Krasnoyarsk, Primorsky, Stavropol and Khabarovsk territories, Amur, Kemerovo, Magadan, Chita regions, Jewish Autonomous Region, Ust-Orda Buryat, Chukotka and Koryak regions autonomous okrugs, the republics of Sakha (Yakutia), Adygea, Khakassia, Altai and the Chechen Republic. In these regions, the predicted seismic activity is 7-8 points and lower.
Moscow and the Moscow region, according to the Russian Academy of Sciences, are not a seismically dangerous area. The maximum possible fluctuations here will not exceed 5 points.

Alexander Kolotilkin

High risk area

Region	Seismic risk index *	Large cities (number of objects requiring priority strengthening)
Krasnodar region	9	Novorossiysk, Tuapse, Sochi, Anapa, Gelendzhik (1600)
Kamchatka region	8	Petropavlovsk-Kamchatsky, Elizovo, Klyuchi (270)
Sakhalin region	8	Yuzhno-Sakhalinsk, Nevelsk, Uglegorsk, Kurilsk, Aleksandrovsk-Sakhalinsky, Kholmsk, Poronaysk, Krasnogorsk, Okha, Makarov, Severo-Kurilsk, Chekhov (460).
The Republic of Dagestan	7	Makhachkala, Buynaksk, Derbent, Kizlyar, Khasavyurt, Dagestan Lights, Izberbash, Kaspiysk (690)
The Republic of Buryatia	5	Ulan-Ude, Severobaikalsk, Babushkin (485)
Republic North Ossetia— Alanya	3,5	Vladikavkaz, Alagir, Ardon, Digora, Beslan (400)
Irkutsk region	2,5	Irkutsk, Shelekhov, Tulun, Usolye-Sibirskoye, Cheremkhovo, Angarsk, Slyudyanka (860)
Kabardino-Balkarian Republic	2	Nalchik, Prokhladny, Terek, Nartkala, Tyrnyauz (330)
Ingush Republic	1,8	Nazran, Malgobek, Karabulak (125)
Karachay-Cherkess Republic	1,8	Cherkessk, Teberda (20)
Tyva Republic	1,8	Kyzyl, Ak-Dovurak, Chadan, Shagonar (145)

_______
*The seismic risk index characterizes the required amount of anti-seismic reinforcements, takes into account seismic hazard, seismic risk and population in large populated areas.

Earthquakes are a terrible natural phenomenon that can bring numerous disasters. They are associated not only with destruction, which may result in human casualties. The catastrophic tsunami waves they cause can lead to even more disastrous consequences.

Which areas of the world are most affected by earthquakes? To answer this question, you need to look at where the active seismic areas are. These are zones of the earth's crust that are more mobile than the surrounding regions. They are located at the boundaries of lithospheric plates, where large blocks collide or move apart. It is the movements of powerful rock layers that cause earthquakes.

Dangerous areas of the world

There are several belts on the globe that are characterized by a high frequency of underground impacts. These are seismically dangerous areas.

The first of them is usually called the Pacific Ring, since it occupies almost the entire ocean coast. Not only earthquakes are frequent here, but also volcanic eruptions, which is why the name “volcanic” or “ring of fire” is often used. The activity of the earth's crust here is determined by modern mountain-building processes.

The second major seismic belt stretches along the high young from the Alps and other mountains of Southern Europe and to the Sunda Islands through Asia Minor, the Caucasus, the mountains of Central and Central Asia and the Himalayas. The collision of lithospheric plates also occurs here, which causes frequent earthquakes.

The third belt stretches across the entire Atlantic Ocean. This is the Mid-Atlantic Ridge, which is the result of the spreading of the earth's crust. Iceland, known primarily for its volcanoes, also belongs to this belt. But earthquakes here are by no means a rare phenomenon.

Seismically active regions of Russia

Earthquakes also occur in our country. Seismically active regions of Russia are the Caucasus, Altai, mountains of Eastern Siberia and the Far East, Komandorsky and Kurile Islands, O. Sakhalin. Tremors of great force can occur here.

One can recall the Sakhalin earthquake of 1995, when two-thirds of the population of the village of Neftegorsk died under the rubble of destroyed buildings. After the rescue work, it was decided not to restore the village, but to relocate the residents to other settlements.

In 2012-2014, several earthquakes occurred in the North Caucasus. Fortunately, their sources were located at great depths. There were no casualties or serious damage.

Seismic map of Russia

The map shows that the most seismically dangerous areas lie in the south and east of the country. At the same time, the eastern parts are relatively sparsely populated. But in the south, earthquakes pose a much greater danger to people, since the population density here is higher.

Irkutsk, Khabarovsk and some others big cities find themselves in the danger zone. These are active seismic areas.

Anthropogenic earthquakes

Seismically active areas occupy approximately 20% of the country's territory. But this does not mean that the rest is completely insured against earthquakes. Tremors with a force of 3-4 points are observed even far from the boundaries of lithospheric plates, in the center of platform areas.

At the same time, with the development of the economy, the possibility of anthropogenic earthquakes increases. They are most often caused by the collapse of the roof of underground voids. Because of this, the earth's crust seems to shake, almost like a real earthquake. And there are more and more voids and cavities underground, because people extract oil and natural gas from the subsoil for their needs, pump out water, build mines for the extraction of solid minerals... And underground nuclear explosions are generally comparable to natural earthquakes in their strength.

The collapse of rock layers in itself can pose a danger to people. Indeed, in many areas, voids form directly under settlements. Recent events in Solikamsk have only confirmed this. But even a weak earthquake can lead to dire consequences, because as a result it can destroy structures that are in disrepair, dilapidated housing in which people continue to live... Also, violation of the integrity of rock layers threatens the mines themselves, where collapses can occur.

What to do?

People are not yet able to prevent such a terrible phenomenon as an earthquake. And they haven’t even learned to predict exactly when and where it will happen. This means you need to know how you can protect yourself and your loved ones during tremors.

People living in such dangerous areas should always have an earthquake plan in place. Since a disaster may find family members in different places, there should be an agreement on a meeting place after the tremors stop. The home should be as safe as possible from falling heavy objects; it is best to attach furniture to the walls and floor. All residents should know where they can urgently turn off gas, electricity, and water in order to avoid fires, explosions and electric shocks. Stairs and passages should not be cluttered with things. Documents and a certain set of products and essentials should always be at hand.

Starting from kindergartens and schools, the population needs to be taught the correct behavior in case of a natural disaster, which will increase the chances of salvation.

Seismically active regions of Russia place special demands on both industrial and civil construction. Earthquake-resistant buildings are more difficult and expensive to build, but the cost of their construction is nothing compared to the lives saved. After all, not only those who are in such a building will be safe, but also those nearby. There will be no destruction and rubble - there will be no casualties.

Universal foundation TISE technology Yakovlev R.N.

9.5. INCREASED SEISMICITY OF THE REGION

9.5. INCREASED SEISMICITY OF THE REGION

From the newspaper "Construction Expert", December 1998, No. 23

"...Particularly acute problems associated with the reliability of houses arise during construction in areas with increased seismic activity. For Russia, this is the Far East and the North Caucasus. For many CIS countries, seismic areas are their entire territory or a significant part of it.

We are interested in the nature of earthquakes, their physical parameters and the degree of influence on structures.

Often the cause of ground vibrations can be local landslides, mudflows, man-made failures caused by the creation of cavities (mining workings, water intake from artesian wells...).

In Russia, a 12-point scale for assessing the strength of an earthquake has been adopted. The main feature here is the degree of damage to buildings and structures<ений. Районирование территории России по балльному принципу приводится в строительных нормах (СНиП II -7-81).

Almost 20% of the territory of our country is located in seismically dangerous zones with earthquake intensity of 6 - 9 points and 50% are subject to 7 - 9 magnitude earthquakes.

Rice. 181. Map of seismic zoning of Russia and neighboring countries

Construction in seismically hazardous zones requires the use of structures of increased strength, rigidity and stability, which causes an increase in the cost of construction in a 7-point zone by 5%, in an 8-point zone by 8% and in a 9-point zone by 10%.

Some features of seismic loads on building elements:

During an earthquake, a building is exposed to several types of waves: longitudinal, transverse and surface;

The greatest destruction is caused by horizontal vibrations of the earth, with which the destructive loads are inertial in nature;

The most characteristic periods of soil vibrations lie in the range of 0.1 - 1.5 seconds;

Maximum accelerations are 0.05 - 0.4 g, with the highest accelerations occurring in periods of 0.1 - 0.5 seconds, which correspond to minimum vibration amplitudes (about 1 cm) and maximum destruction of buildings;

A long period of oscillations corresponds to minimum accelerations and maximum amplitudes of soil vibrations;

Reducing the weight of the structure leads to a decrease in inertial loads;

Vertical reinforcement of building walls is advisable if there are horizontal load-bearing layers in the form of, for example, reinforced concrete floors;

Seismic insulation of buildings is the most promising way to increase their seismic resistance.

This is interesting

The seismic isolation mechanism is a columnar strip foundation built using TISE technology.

A carbon steel rod with a diameter of 20 mm, which passes through the grillage, is used as vertical reinforcement for the foundation column. The rod has a smooth surface covered with tar. At the bottom it is equipped with an ending embedded in the body of the column, and at the top with an ending protruding from the grillage and equipped with an M20 thread for a nut (RF patent No. 2221112 of 2002). The support itself is included in the grillage array by 4...6 cm (Fig. 182, a).

Rice. 182. Seismic isolating foundation with a central rod: A - neutral position of the foundation support; B - deflected position of the foundation support; 1 - support; 2 - rod; 3 - lower end; 4 - nuts; 5 - grillage; 6 - cavity with sand; 7 - blind area; 8 - directions of ground vibrations

After concreting, three to four cavities 0.6...0.8 m deep are made around each of the supports with the same foundation drill and filled with either sand, or a mixture of sand and expanded clay, or slag. In sandy soil such cavities need not be made.

Upon completion of construction, the rod nuts are tightened with a torque wrench. This creates an “elastic” hinge in the area where the pillar meets the grillage.

During horizontal vibrations of the soil, the pillars deviate relative to the elastic hinge, the rod is stretched, while the grillage with the building remains motionless by inertia (Fig. 182, b). The elasticity of the soil and rods returns the pillars to their original vertical position. During the entire life of the building, free access to the pole reinforcement tensioning units must be provided both along the outer perimeter of the house and under the internal load-bearing walls. After completion of construction and after significant seismic vibrations, the tightening of all nuts is restored with a torque wrench (M = 40 - 70 kg/m). This version of a seismic isolating foundation can be considered to some extent industrial, since it includes rods and nuts, which are easier to produce in production.

TISE technology provides for the implementation of seismic isolating supports in a more democratic way, accessible to developers with limited production capabilities. As a reinforcing elastic element, two brackets from a reinforcement bar with a diameter of 12 mm with bent ends are used (Fig. 183). The middle part of the reinforcement branches over a length of about 1 m is lubricated with tar or bitumen (at an equal distance from the edges) to prevent adhesion of the reinforcement to the concrete. During seismic vibrations of the soil, the reinforcement bars in their middle part stretch. With horizontal soil displacements of 5 cm, the reinforcement stretches by 3...4 mm. With a tensile zone length of 1 m, stresses of 60...80 kg/mm 2 arise in the reinforcement, which lies in the zone of elastic deformations of the reinforcement material.

Rice. 183. Seismic isolating foundation with reinforcing brackets: 1 - support; 2 - bracket; 3 - grillage; 4 - cavity with sand

This is not the foundation, but...

When building in seismically active areas, the use of roofing made of clay or sand concrete tiles must be justified.

Many Japanese individually built houses with a light frame are covered with high-quality clay tiles. In conditions of dense Japanese buildings, such houses can withstand typhoons well. However, during an earthquake, under the weight of the tiled roof, the house collapses, burying the inhabitants under its excessive weight.