What is the operating principle of a seismograph based on? Measuring instruments seismograph

To detect and record all types of seismic waves, special instruments are used - seismographs. In most cases, the seismograph has a weight with a spring attachment, which during an earthquake remains motionless, while the rest of the device (body, support) begins to move and shifts relative to the load. Some seismographs are sensitive to horizontal movements, others to vertical ones. The waves are recorded by a vibrating pen on a moving paper tape. There are also electronic seismographs (without paper tape).

Earthquake magnitude (from Latin magnitudo - importance, significance, size, greatness) is a quantity characterizing the energy released during an earthquake in the form of seismic waves. The original magnitude scale was proposed by the American seismologist Charles Richter in 1935, which is why the magnitude value is commonly referred to as the Richter scale.

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

In the theory of calculation of structures for seismic impacts (seismicity theory), as in other areas of the dynamics of various mechanical systems, calculations with distributed and discrete parameters (mass) are usually used. A system with discrete parameters, although of an approximate nature, is more universal and it is possible to obtain a solution for a system of any complexity, as a result of which it is most often used in engineering calculations.

To obtain dynamic design schemes in the form of a system with a finite number of degrees of freedom, the actual distributed mass of the system is concentrated in certain places in the form material points. The result is a weightless system carrying a certain amount of concentrated mass. The number of degrees of freedom of the system is equal to the number of independent geometric parameters that uniquely determine the position of concentrated masses at an arbitrary moment in time.

It is advisable to concentrate the masses of the system under consideration in places where significant loads are concentrated. The reliability and accuracy of the calculation results largely depends on the successful choice of the design scheme and its compliance with the actual operating conditions of the structure.

Rice. 55Calculation diagram of a building subjected to seismic loads

As an example, let us consider the calculation method for a building that has floors subject to seismic influence. By concentrating the mass of the structure at the levels of the floor and the foundation slab, we obtain a system in the form of a cantilever rod rigidly embedded in the foundation slab, lying in conditions of complete adhesion on the surface of the elastic inertial base (Fig. 55).

We will consider the transverse vibrations of the rod in the plane (zy). The origin of the coordinate system will be placed at the center of gravity of the base of the foundation of the structure. The height rigidity of the rod varies according to an arbitrary law. No restrictions are imposed on the nature of the deformation of the rod, except for the requirement of linear deformability.

The position of the system at an arbitrary time t > 0 is determined by linear horizontal displacements (),(i=1.2….n+1) (Fig. 55).

Since there is movement of foundation soils during an earthquake on the free surface of the earth, assuming the absence of a structure, it is accepted here in advance given value. Consequently, if we manage to determine the quantities (i=1,2,...,n+1), we can determine the position of a given system through the values of these quantities at an arbitrary moment in time.

It follows that the system under consideration, having (n+1) number of concentrated masses, has (n + I) degrees of freedom.

Oscillations linear system for a given external kinematic influence, it is completely determined by its inertial and deformative properties and energy dissipation parameters. The inertial properties of the system under consideration are characterized by concentrated masses (i=1,2,...,n+1), and the nature of their distribution over height. The deformative properties of the system can be characterized using unit displacements), which represent the horizontal displacement of points i from the action of a unit horizontal force applied at point k. The displacement within the framework of the adopted design scheme is determined

Where horizontal movements point i from the action of a unit horizontal force applied at point k, caused respectively by: deformations of the structural elements of the building; relative shift between the base of the foundation slab and the base; by rotating the base of the foundation slab relative to the base.

The expression can be written in the following form

Since the foundation slab is considered absolutely rigid, therefore, when i=n+1, or k=n+1 it should be taken Here it is determined by Mohr’s formula; - are the coefficients of quasi-static stiffness of the base under uniform shear and uneven compression or tension and their values can be determined from the following relationships.

Where the following designations are adopted: - speed of propagation of transverse waves in soils; p - density of foundation soils; F-area of the base of the foundation slab; - moment of inertia of the area of the base of the foundation slab relative to the x-axis.

To take into account the dissipation of energy during system oscillations, we will use Voigt’s theory, according to which dissipative Forces are applied to concentrated masses in the state of motion of the system, the magnitude of which is proportional to the speed of movement of the concentrated masses. The proportionality coefficients for the system under consideration are determined by the formula

Magnitude - logarithmic vibration decrement, characterizes energy dissipation according to the corrected Voigt hypothesis due to the internal inelastic resistance of structural materials during their deformation; - characterizes the radiation of energy in the base due to shear deformations occurring on the contact surface between the foundation slab and the base; - energy dissipation coefficient due to uneven linear deformations occurring on the contact surface between the foundation slab and the base.

The acoustic resistance of the base under uniform shear and uneven compression and tension is determined by known relationships.

Where - speed of propagation of longitudinal waves in the soil foundation.

Let's use the force method and write down the amount of displacement yi(t) arbitrary mass with number i=1,2,…n+1, from the action of inertial forces and forces taking into account energy dissipation in the system under consideration:

Here the inertial force acting on kth mass and is determined by D'Alembert's principle:

The resistance force arising in To- th mass, according to Voigt’s hypothesis, is directly proportional to the speed of its movement:

Substituting expressions (79) and (80) into (78) and after some transformations, we obtain the differential equation of motion of a given system in the following form:

To calculate structures for seismic impacts, zero initial conditions are valid, ta. it is assumed that before the earthquake the structure is at rest. During an earthquake, a structure goes into motion and its state is characterized by a system of equations (81).

To calculate the system of differential equations (81), the Laplace transform method is used, i.e. the required functions are found by the formula

(82)

where is the Laplace image of the function y i (t) and is determined by the formula

Substituting (82) into (81) and taking into account the zero initial conditions of the problem, we obtain:

The latter represents a system of algebraic equations regarding displacements in Laplace images.

Solution (84) is written in images as

Where - is the determinant of a system of inhomogeneous algebraic equations (84); D(s) is the determinant of the same system for unknowns.

Applying the inverse Laplace transform operations to expression (85) using the drill theorem, we obtain a solution to the problem in the following form:

In traditional methods of calculating a structure for seismic resistance, as a rule, the following simplifying assumption is used that the base of the structure is absolutely solid body, i.e. c = ¥ and c 1 = ¥. Based on the condition of the existence of complete adhesion between the foundation slab and the base on their contact surface, it is obvious that the mass with number n+1, the foundation slab completely follows the law of motion of the foundation. On the other hand, since the law of motion of the foundation in this case is considered an initial known function, therefore, the law of motion of the foundation slab should also be considered a known quantity. Therefore, the number of degrees of freedom of the system under consideration (see Fig. 55) decreases by one unit and takes a value equal to n

The required quantities in this case are the movements of concentrated masses with numbers i=1,2..n.

Taking this circumstance into account, the equation of motion of the structure from (74) is simplified and takes the form

To solve the system of differential equations (87) with constant coefficients, the method of decomposition of vibrations into modes is used, based on the method of separation of variables, i.e.

First, to determine the natural frequency and natural vector, the natural oscillations of the system are considered without taking into account resistance forces. In this case, from (87) we obtain the equations of motion of the system without taking into account the resistance forces in the free oscillation mode

Substituting solution (88) into (90), taking into account the conditions of orthogonality of natural vibration modes, i.e.

and after a series of transformations we get

The fulfillment of these equalities for an arbitrary value of t is possible only if each of them separately is equal to the same constant for any value of v. Denoting this constant by , we get

The last equations are a system of n linear homogeneous algebraic equations with respect to unknowns for each v= 1,2... n vibration mode.

Seismograph

Seismograph- a special measuring device that is used to detect and record all types of seismic waves. In most cases, the seismograph has a weight with a spring attachment, which during an earthquake remains motionless, while the rest of the device (body, support) begins to move and shifts relative to the load. Some seismographs are sensitive to horizontal movements, others to vertical ones. The waves are recorded by a vibrating pen on a moving paper tape. There are also electronic seismographs (without paper tape).

Until recently, mechanical or electromechanical devices were mainly used as seismograph sensing elements. It is quite natural that the cost of such instruments containing elements of precision mechanics is so high that they are practically inaccessible to the average researcher, and the complexity of the mechanical system and, accordingly, the requirements for the quality of its execution actually mean the impossibility of manufacturing such devices on an industrial scale.

The rapid development of microelectronics and quantum optics has currently led to the emergence of serious competitors to traditional mechanical seismographs in the mid- and high-frequency regions of the spectrum. However, such devices based on micromachine technology, fiber optics or laser physics have very unsatisfactory characteristics in the region of infra-low frequencies (up to several tens of Hz), which is a problem for seismology (in particular, the organization of teleseismic networks).

There is also a fundamentally different approach to constructing the mechanical system of a seismograph - replacing the solid inertial mass with a liquid electrolyte. In such devices, an external seismic signal causes a flow of working fluid, which, in turn, is converted into electricity using a system of electrodes. Sensitive elements of this type are called molecular electronic. The advantages of seismographs with liquid inertial mass are low cost, long service life (about 15 years), and the absence of precision mechanics elements, which greatly simplifies their manufacture and operation.

Computerized seismic measuring systems

With the advent of computers and analog-to-digital converters, the functionality of seismic equipment has increased dramatically. It is now possible to simultaneously record and analyze in real time signals from several seismic sensors and take into account signal spectra. This provided a fundamental leap in the information content of seismic measurements.

Examples of seismographs

Molecular electron seismograph. .
Autonomous bottom seismograph. . Archived from the original on December 3, 2012.

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Synonyms:

See what a “Seismograph” is in other dictionaries:

Seismograph... Spelling dictionary-reference book

- (Greek, from seismos vibration, shaking, and grapho I write). An apparatus for observing earthquakes. Dictionary of foreign words included in the Russian language. Chudinov A.N., 1910. SEISMOGRAPH Greek, from seismos, shock, and grapho, I write. Apparatus for... ... Dictionary of foreign words of the Russian language

Syn. term seismic receiver. Geological Dictionary: in 2 volumes. M.: Nedra. Edited by K. N. Paffengoltz et al. 1978 ... Geological encyclopedia

Geophone, seismic receiver Dictionary of Russian synonyms. seismograph noun, number of synonyms: 2 geophone (1) ... Synonym dictionary

- (from seismo... and...graph) a device for recording vibrations of the earth's surface during earthquakes or explosions. The main parts of a seismograph are the pendulum and the recording device... Big encyclopedic Dictionary

- (seismometer), a device for measuring and recording SEISMIC WAVES caused by movement (EARTHQUAKE or explosion) in the earth's crust. The vibrations are recorded using a recording element on a rotating drum. Some seismographs are capable of detecting... Scientific and technical encyclopedic dictionary

SEISMOGRAPH, seismograph, husband. (from the Greek seismos shaking and grapho I write) (geol.). A device for automatically recording vibrations of the earth's surface. Dictionary Ushakova. D.N. Ushakov. 1935 1940 … Ushakov's Explanatory Dictionary

SEISMOGRAPH, huh, husband. A device for recording vibrations of the earth's surface during earthquakes or explosions. Ozhegov's explanatory dictionary. S.I. Ozhegov, N.Yu. Shvedova. 1949 1992 … Ozhegov's Explanatory Dictionary

Seismograph- - a device designed to record vibrations of the earth's surface caused by seismic waves. It consists of a pendulum, for example, a steel weight, which is suspended on a spring or thin wire from a stand firmly fixed in the ground.... ... Oil and Gas Microencyclopedia

seismograph- Conversion device mechanical vibrations soil in electric and subsequent recording on photosensitive paper. [Dictionary of geological terms and concepts. Tomsk State University] Topics geology, geophysics Generalizing... ... Technical Translator's Guide

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Use: seismology, for monitoring and recording vibration movements earth's crust during various dynamic processes both on the surface and inside soil masses, as well as any technological equipment, including nuclear reactors. The essence of the invention: contains a hermetic housing in which a chassis, a pendulum, a damping device, a pendulum displacement transducer, a gravity moment compensation unit, a rolling unit and elements of communication and information transmission to the control center are located. All elements placed on the pendulum, in addition to their direct functions, create an additional moment of inertia aimed at reducing the resonant frequency due to their peripheral placement symmetrically relative to the center of gravity of the pendulum. The housing of the device, in addition to its protective functions, is involved in creating a decrease in the quality factor of the chassis’s own resonant frequency through the use of a fastening system and due to the easy press fit of the chassis in the housing. The compact placement of the units is due to the choice of the shape of the pendulum: a titanium tube with beveled ends and with technological and mounting holes, as well as the implementation of the rolling unit: a pair of knives, one of which is rigidly fixed to the cylindrical shape of the pendulum, and the other is connected to the chassis, and the knives are placed relative to each other each other with the possibility of setting the center line of their rounded edges in one straight line. 6 ill.

The invention relates to seismology, in particular to the designs of seismic signal receivers, and can be used to monitor and record vibrational movements of the earth’s crust during various dynamic processes both on the surface and inside soil masses, as well as any technological equipment, including nuclear reactors. The VEGIK seismograph is known for studying the seismic effect of explosions, recording earthquakes and microseisms of the first kind. The seismograph contains a pendulum suspended from stands on two pairs of mutually perpendicular thin steel plates (a cross elastic hinge), forming the axis of rotation of the pendulum. To record vertical vibrations, the axis of rotation is given a horizontal position, and the pendulum is in a horizontal position (the center of gravity in the same horizontal plane with the axis of rotation is held using a steel helical spring). The equilibrium position of the pendulum is adjusted by a screw that changes the tension of the spring, and the period of natural oscillation (T 1 = 0.8-2 s) is adjusted by changing the angle of inclination of the spring and changing the hanging steel plates. To record horizontal vibrations, the spring is removed from the pendulum, the device is rotated 90° and placed on three set screws. The pendulum ends in a light duralumin form, at the end of which a light cylindrical frame made of plexiglass with two windings (coils) of thin enameled copper wire wound on it is rigidly fixed. The coil is located in the cylindrical air gap of a permanent magnet. One of the coils is used to record the movement of the pendulum, the other is used to adjust its damping. The pendulum with stands and magnet are mounted on a flat frame, which is rigidly mounted in a metal case. One of the side walls for monitoring the state of the pendulum is made of plexiglass. Vibrations are usually recorded using small-sized galvanometers. The disadvantage of the known seismograph is low reliability due to the presence of a cross-shaped suspension. Sharp vibrations (during explosions, shocks) crush or cut off the plates. The closest in technical essence to the proposed invention is the VBP-3 seismograph, containing a pendulum consisting of two unequal, but similar in magnitude masses, placed symmetrically on both sides of the axis of rotation. The pendulum is made in the form of a flat aluminum frame, on one side of which holes are drilled to reduce weight. For strength, the frame has stiffening ribs. Brass axle shafts, mounted on a frame and mounted in radial ball bearings, form the axis of rotation of the pendulum. A cylindrical frame made of electrolytic copper, mounted on the pendulum, serves to dampen its own vibrations. A flat induction coil is wound around the frame with a thin enameled copper wire, serving as a converter. The pendulum is mounted on bearings in the sockets of a brass bracket, rigidly attached to the pole pieces of a horseshoe-shaped permanent magnet made of Magnico alloy. The soft iron pole pieces are glued to the magnet with BF glue. A cylindrical soft iron core is also mounted on the bracket on two guide rods. A uniform radial magnetic field is formed in the air gap between the pole pieces and the core. When magnetizing, the core is removed, otherwise the main magnetic flux is directed through it, and not through the magnet. Instead of the core, a brass wedge is inserted into the air gap to avoid magnet breakage. In this gap there is a copper damper frame with a transducer induction coil. With such a suspension system, the pendulum oscillates with angular turns of up to 30 o in both directions from the equilibrium position, without hitting the limiters (bracket). A magnet with a pendulum is inserted into a recess in the frame (chassis) and is rigidly attached to it with a crossbar and bolts. The ends of the induction coil are brought out to the block on the frame. A cable is connected to it, passed through a sealed gland in the frame. A protective casing made of non-magnetic material is bolted to the frame through a rubber gasket and ensures the tightness of the device up to a pressure of 2 atm. The frame has a handle for carrying the device. The bracket, magnet, frame and casing, rigidly connected to each other, form the base of the device, which during measurements follows the movement of the object, while the pendulum tends to remain at rest. An EMF is excited in the induction coil, proportional to the speed of movement of the base relative to the pendulum. This EMF is supplied to the galvanometer terminals of a magnetoelectric oscilloscope (recorder). The disadvantage of the known seismograph is low sensitivity, due to the fact that the pendulum is suspended on axes rotating in ball bearings. The purpose of the invention is to increase sensitivity, expand the measurement range towards lower frequencies, anti-load capacity and create the technical possibility of placement in vertical channels and wells (reduction of dimensions). Figure 1 shows the design diagram of the seismograph; figure 2 - rolling unit; figure 3 - section along A-A in figure 2; figure 4 - node I in figure 3; Fig.5 - section along B-B in Fig.2; in Fig.6 - node II in Fig.5. The seismograph consists of a rigid cylindrical body 1 (sealed), which is attached to the research object 4 through a clamping ring 2 with pins 3. Inside the housing 1 there is a chassis 5, which is fastened to the housing 1 by means of a locking threaded ring 6, fixed by an upper sealed cover 7. To eliminate mutual movements of the housing 1 and the chassis caused by differences in the temperature coefficients of expansion of materials, a flat preloaded with a force of 400 N is provided spring 8 located between the bottom of the body 1 and the base of the chassis 5. Structural tongue and groove (without position) in this connection prevent rotation of the chassis 5 relative to the body 1. Inside the body 1 there is a pendulum 9 made of a titanium tube with beveled ends and with technological and fastening holes on its forming surface. The pendulum 9 is connected to the rolling unit 10 by means of a titanium bracket 11. The seismograph has a measuring transducer for the movement of the pendulum, a damping device, a gravity moment compensation unit and elements of communication and transmission of information to the control center. On the supporting structure of the pendulum 9, symmetrically relative to the horizontal plane passing through the center of gravity, the following elements are installed as they move away from this center of gravity: contactor 12 (shunt part) of the displacement transducer, frame 13 made of conductive non-magnetic material with power winding 14 of the compensation unit and a passive element 15 (copper plate) damping device. In addition, the pendulum 9 contains elements that increase the rigidity of the pendulum and elements for balancing the pendulum (not shown). Mounted on the chassis 5 are the following parts: coils 16 - active displacement transducer systems, magnetic systems 17 of the gravity moment compensation unit, magnetic systems 18 of damping devices, swing unit 10 (suspension) of the pendulum 9, magnetic shields 19, terminal blocks (not shown) and supporting elements (not shown) of wire routing (elements of communication and transmission of information to the control center). Active systems - displacement transducer coils 16 consist of a U-shaped magnetic core made of electrolytic steel, a winding made of PNET - KSOT wire, containing 150 turns each, and a holder with magnets with wire fixing elements. The design of the holder includes elements that increase its rigidity (for example, in the form of additional stiffeners). Magnetic systems 17 of the gravity compensation unit are made in the form of a coaxial-cylindrical structure with a ring magnet (from material 10 NDK 35T5A) and magnetic cores (from alloy 49 KF 2), providing a cylindrical working gap with induction magnetic field 1 Tl. The shell (without position) of the magnetic system 17 is made of titanium alloy. The parts of the magnetic system are connected using special glue that can withstand heating up to 400 o C (for example, K-400). In addition, the compensation unit can be made in the form of an eddy current induction drive, the stator part of which is rigidly fixed to the chassis. The magnetic systems of 18 damping devices are made in the form of an O-shaped magnetic circuit with a pair of magnets connected in series. The magnetic system fastening elements allow damping adjustment by shunting part of the working magnetic flux. Magnetic screens 19 are plates made of St10 steel and are designed to weaken the influence of stray fields of magnetic systems on passive elements - contactors 12 of the pendulum displacement transducer. The terminal block is made of ceramic and carries terminals to which the wires are connected using resistance welding. Wire routing support elements are made of ceramic and are located both on the chassis itself and in specially designated channels. The rolling unit has a support blade 20, rigidly connected by means of a bracket 11 to the pendulum 9, and an auxiliary blade 21 connected to the chassis 5 through an elastic element 22 (power spring). The knives 20 and 21 are installed opposite each other and have a system (adjustment) for aligning the center line of their rounded edges (the axes of the knives) vertically - a nut 23, and horizontally by rotating the knife 21 around its longitudinal axis with rods inserted into special holes 24. The support unit for the pendulum suspension is made of P18 steel, hardened to HRC 65 units, and is a structure containing cushions 25 for the support knife 20, plates 26 - limiters of the horizontal movements of the knife, a groove 27 for placing the power spring 22 and screws 28 for setting the required clamping force with auto-fixing. All elements of electromagnetic systems (displacement transducer, damping device and compensation unit) are elements of original design, which are based on well-known design and technological methods. The seismograph works as follows. The operating principle is based on the transformation of vertical disturbing (vibration) movements of the seismograph base into rotational movements of the vertical pendulum 9 Golitsyn. To bring the system into equilibrium, a constant moment M m must act in the axis, independent of the angle, compensating for the effect of gravity. The value of this moment is determined by the expression M m = m g l cos, where m is the mass of the pendulum; g - free fall acceleration, l - lever length; - sagging angle. The center of gravity (CG) of the pendulum 9 is acted upon by a force that creates a moment m g l. The compensating moment is created by a pair of forces of the electromagnetic system 13, 14, 17. Moreover, the fixed element is the magnetic system 17, which excludes the influence of external magnetic fields (due to shielding of the magnetic circuit winding of the system 17). The totality of the masses of elements 12, 13, 14, 15, the masses of the pendulum 9, as well as their mutual arrangement(symmetrically relative to the horizontal plane passing through the central center of the pendulum), the moment of inertia I and the position of the central center of the pendulum are determined at the periphery of the pendulum. Neglecting friction in the support of the rolling unit 10, the expression for the amplitude-frequency characteristic (AFC) can be represented as = where A out is the amplitude of movement of the contactor 12 of the pendulum displacement transducer; Ain is the amplitude of vertical input movements; - 6.28 F - circular frequency of vibration effects; F - vibration frequency; o = - natural frequency of the pendulum;
bc - attenuation decrement (selected during the setup process);
R - distance from the axis of rotation. Rotational movement the vertical pendulum 9 is converted by means of closure 12 and coil 16 into an electrical signal. The inductive half-bridge, on the basis of which the pendulum displacement transducer is made, is powered by an alternating voltage with a frequency of 5 kHz and an amplitude of up to 30 V (mostly 25 V). Electromagnetic systems 13, 14, 17, supporting the pendulum 9 in a suspended state, are powered by a current stabilizer, which is connected by a KUGVEV ng cable (via a power line with an alternating voltage of 5 kHz) and a KVVGE ng cable (via a power line DC). The seismograph has been tested and confirmed its effectiveness. The seismograph is compact (dimensions: body height H = 350 mm 0.5, diameter d = 74 mm 0.5) due to the use of some structural components to perform several functions. Thus, nodes 13, 14, 17, in addition to creating a compensating pair of forces, perform the additional function of a damper. Knives 20, 21, in addition to performing the function of an axis of rotation, have the function of maintaining contact under overloads of more than 1 g due to their opposing arrangement. All elements placed on the pendulum, in addition to their direct functions, create an additional moment of inertia aimed at reducing the resonant frequency due to their peripheral placement symmetrically relative to the central center of the pendulum. Housing 1, in addition to its protective functions, is involved in creating a decrease in the quality factor of the natural resonant frequency of the chassis 5 through the use of a fastening system (nut 6) and due to the easy press fit of the chassis 5 in the housing 1. The use of the invention will improve the reliability of operation of industrial units in areas with seismic activity. High sensitivity in the low frequency range (0.1-2 Hz) makes this device indispensable for monitoring the onset of emergency situations especially at explosive facilities using nuclear energy.

Claim

A SEISMOGRAPH containing a sealed housing in which a chassis, a pendulum, a rolling unit, an electromagnetic transducer of pendulum movement, a gravity moment compensation unit, an electromagnetic damping device and elements of a communication line with the recorder are located, characterized in that the electromagnetic transducer of the pendulum movement, a moment of force compensation unit gravity and the electromagnetic damping device are made of two identical systems, placed symmetrically relative to the plane passing through the center of gravity of the pendulum and perpendicular to its axis of rotation, while the pendulum is made in the form of an extended figured hollow cylindrical shape, and the rolling unit is made in the form of a pair of knives, one of which is rigidly fixed to a cylindrical shape, and the other knife is connected to the chassis through an elastic element, and the knives are placed opposite each other with the possibility of setting the center line of their rounded edges along one straight line, the compensation unit is made in the form of a coaxially mounted magnetic system mounted on the chassis , and a hollow blind coil, the winding of which is placed on a frame made of conductive non-magnetic material, rigidly mounted on the pendulum, on which the passive elements of the damping device and the pendulum displacement transducer are installed, and the magnetic systems of the damping device and the displacement transducer are fixed to the chassis, while the passive elements of the transducer the movements of the pendulum, the gravity moment compensation unit and the damping device are located at opposite ends of the cylindrical pendulum.

| Seismograph

Seismograph(Greek origin and formed from two words: “ seismos" - shaking, shaking, and " grapho" - write, record) is a special measuring device that is used in seismology to detect and record all types of seismic waves.

Ancient times

China is famous for its inventions, but they, alas, become outdated and change. Paper has evolved to digital media, gunpowder has long become “liquid,” and even compasses have come in more than a dozen varieties. Or, for example, a seismograph. A modern device for recording earth vibrations looks solid - like a lie detector or a spy device. It is not at all like the very first seismograph - a little ridiculous in appearance, but quite accurate. It was invented during the Han Dynasty (25-220 AD) by the scientist Zhang Heng.

The creator of the first seismograph was born in Nanyang (Henan Province). Even as a child, Han showed a love for science. Over the years he entered Chinese history and did a lot of useful things for astronomy and mathematics. IN historical notes At that time, it appears that this inventor was calm and balanced and tried to keep a low profile. In addition to his passion for science, Zhang Heng knew how to write poetry.

Inventor of the seismograph

Earthquake – imbalance between Yin and Yang In ancient times, it was believed that earthquakes were a very unkind sign and the wrath of heaven. In ancient Chinese philosophy, a special teaching was even invented that examined the balance between the two forces of Yin and Yang. Naturally, this science could not do without explaining such a phenomenon as an earthquake. According to the Chinese of that time, the earth was shaking for a reason, but because of a global imbalance.

Why do earthquakes sometimes occur, the force of which can lead to disaster? Everything was attributed to the wrong decisions of the Chinese rulers. Have taxes increased? Heaven will punish China with an earthquake! War started? Expect trouble! A large percentage of the earthquakes that occurred then were meticulously described. Historians considered it important to write about everything that happened on such an unfavorable day.

Thanks to Zhang Heng's research, it was found that earthquakes are a natural phenomenon, which can be known in advance. For this purpose he created a seismograph.

The operating principle of the first Chinese seismograph

The scheme according to which the device worked was as follows:

When an earthquake began, the first tremors of the earth caused the detector to shake.

At the same time, the ball, which was placed inside the dragon, began to move.

Then he fell from the mouth of the mythical reptile directly into the mouth of the toad.

The working principle of the Chinese seismograph
As the ball fell, a characteristic clanging sound was heard. Surprisingly, the first seismograph even indicated the direction in which the epicenter of the earthquake was located (for this, additional dragons were attached to the device). For example, if the ball fell out of the dragon from the eastern part of the device, then trouble should be expected in the west.

The first seismograph is not only a scientific, but also an artistic artifact. Why does its design include dragons and toads? They are a philosophical symbol of time. Accordingly, dragons are Yin, and toads are Yang. The interaction between them symbolizes the balance between “up” and “down”. Even taking into account everyone scientific discoveries, Zhang Heng did not forget to weave traditional beliefs into his invention.

Fate is a villain

The fate of many ancient scientists was not the most rosy (some were even burned at the stake for their beliefs). Indeed, it is one thing to invent something that will glorify you for centuries, and another thing to make sure that your contemporaries appreciate you. Even Zhang Heng could not avoid skepticism when demonstrating the seismograph to Emperor Shun Yang Jia. The courtiers reacted to the scientist's invention with great distrust.

Skepticism was a little dispelled in 138 AD, when Zhang Heng's seismograph recorded an earthquake in the Longxi region. But even after proving that the device worked successfully in the field, most were afraid of Zhang Heng. Yes, the ancient Chinese were not without superstitions.

Chinese seismograph

Exact copy of the device

The original seismograph has long since sunk into oblivion. However, Chinese and foreign scientists who researched Zhang Heng's works were able to reconstruct his invention. Latest tests confirm: seismograph ancient Chinese can detect an earthquake with an accuracy that is almost as good as modern equipment.

Chinese seismograph in a museum
Today, the recreated ancient seismograph is kept in the exhibition hall of the Chinese History Museum in Beijing.

19th century

In Europe, earthquakes began to be seriously studied much later.

In 1862, the book “The Great Neapolitan Earthquake of 1857: Basic Principles of Seismological Observations” was published by the Irish engineer Robert Malet. Malet made an expedition to Italy and drew up a map of the affected territory, dividing it into four zones. The zones introduced by Malet represent the first, rather primitive, scale of shaking intensity. But seismology as a science began to develop only with the widespread appearance and introduction into practice of instruments for recording ground vibrations, i.e., with the advent of scientific seismometry.

In 1855, Italian Luigi Palmieri invented a seismograph capable of recording distant earthquakes. It operated on the following principle: during an earthquake, mercury was spilled from a spherical volume into a special container, depending on the direction of vibration. The contact indicator with the container stopped the watch, indicating the exact time, and triggered a recording of ground vibrations on the drum.

In 1875, another Italian scientist, Filippo Sechi, designed a seismograph that turned on a clock at the moment of the first shock and recorded the first vibration. The first seismic record that has come down to us was made using this device in 1887. After this, rapid progress began in the field of creating instruments for recording ground vibrations. In 1892, a group of English scientists working in Japan created the first fairly easy-to-use device, the John Milne seismograph. Already in 1900, a worldwide network of 40 seismic stations equipped with Milne instruments was operating.

XX century

The first seismograph of modern design was invented by the Russian scientist, Prince B. Golitsyn, who used the conversion of mechanical vibration energy into electric current.

B. Golitsyn
The design is quite simple: the weight is suspended on a vertical or horizontal spring, and a recorder pen is attached to the other end of the weight.

A rotating paper tape is used to record the vibrations of the load. The stronger the push, the further the pen deflects and the longer the spring oscillates. A vertical weight allows you to record horizontally directed shocks, and vice versa, a horizontal recorder records shocks in the vertical plane. As a rule, horizontal recording is carried out in two directions: north-south and west-east.

Conclusion

As a rule, large earthquakes do not occur unexpectedly. They are preceded by a series of small, almost imperceptible shocks of a special nature. By learning to predict earthquakes, people will be able to avoid death due to these disasters and minimize the material damage they cause.

WITH ancient times one of the most terrible natural Disasters are earthquakes. We subconsciously perceive the surface of the earth as something unshakably strong and solid, the foundation on which our existence stands.

If this foundation begins to shake, collapsing stone buildings, changing river courses and erecting mountains in place of plains, this is very scary. It is not surprising that people tried to predict in order to have time to escape by escaping from a dangerous area. This is how the seismograph was created.

What is a seismograph?

Word "seismograph" is of Greek origin and is formed from two words: “seismos” - shaking, vibration, and “grapho” - writing, recording. That is, a seismograph is a device designed to record vibrations of the earth's crust.

The first seismograph, the mention of which remains in history, was created in China almost two thousand years ago. The scientist astronomer Zhang Hen made for the Chinese emperor a huge two-meter bronze bowl, the walls of which were supported by eight dragons. In the mouth of each of the dragons lay a heavy ball.

A pendulum was suspended inside the bowl, which, when subjected to an underground shock, struck the wall, causing the mouth of one of the dragons to open and drop a ball, which fell directly into the mouth of one of the large bronze toads sitting around the bowl. According to the description, the device could record earthquakes occurring at a distance of up to 600 km from the place where it was installed.

Strictly speaking, each of us can make a simple seismograph ourselves. To do this, hang a weight with a pointed end exactly above a flat surface. Any vibration in the ground will cause the weight to oscillate. If you powder the area under the load with chalk powder or flour, then the stripes drawn by the sharp end of the weight will indicate the strength and direction of the vibrations.

True, such a seismograph is not suitable for a resident of a big city whose house is located next to a busy street. Passing heavy trucks will continually vibrate the soil, causing micro-oscillations of the pendulum.

Seismographs used by scientists

The first seismograph of modern design was invented by the Russian scientist, Prince B. Golitsyn, who used the conversion of mechanical vibration energy into electric current.

The design is quite simple: the weight is suspended on a vertical or horizontal spring, and a recorder pen is attached to the other end of the weight.

Why are seismographs needed?

Seismograph records are necessary to study the patterns of occurrence of tremors. This is done by a science called seismology. Of greatest interest to seismologists are areas located in so-called seismically active places - in fault zones of the earth's crust. There, movements of huge layers of underground rocks are also common - i.e. something that usually causes earthquakes.

As a rule, large earthquakes do not occur unexpectedly. They are preceded by a series of small, almost imperceptible shocks of a special nature. By learning to predict earthquakes, people will be able to avoid death due to these disasters and minimize the material damage they cause.