RU2431158C1 - Method of removing elastic stress in earth's crust to prevent catastrophic earthquakes - Google Patents

Abstract

FIELD: physics. ^ SUBSTANCE: analysed territory is broken into cells. The speed of seismotectonic deformations in each cell, which characterises the background value, is determined. The average background speed of seismotectonic deformations in all cells is determined. At least one electromagnetic pulse emitter is placed on the analysed territory. The earth's curst is exposed to electromagnetic pulses. The speed of seismotectonic deformations in each cell during exposure is determined, as well as the ratio of that speed to the corresponding background value of that cell. The average value of the ratio of speed values on all cells is determined. Zones with high concentration of elastic stress are determined by the ratio of speed values higher than the average value. The selected zones are further exposed to electromagnetic pulses and the speed of seismotectonic deformations is determined. The average speed of seismotectonic deformations for the entire exposure time and the exposure time are determined. The average value of the removed elastic stress in the earth's crust is determined. ^ EFFECT: high efficiency of removing elastic stress from the earth's crust, and reduced negative impact on the environment. ^ 1 dwg

Description

The invention relates to geophysical research in the field of geoelectricity and seismology, in particular to the removal of elastic stresses in the earth's crust by irradiation with electromagnetic pulses, and can be used to prevent catastrophic earthquakes in areas of high concentration of elastic stresses that occur within areas with a high population density, a large technogenic load on the natural complex, where mining facilities, oil and gas production, and large hydrotechnics are located technical and hydropower facilities, as well as territories where particularly important facilities, nuclear facilities, the chemical industry and other environmentally hazardous facilities are located.

A known method of controlling the displacement mode in fragments of seismically active tectonic faults, including external action on the selected fragment, registration of the initial parameters of the fracture fragment, testing the effect on the fracture fragment to assess the initial level of tectonic stresses in it, the subsequent impact on the selected fragment to initiate smooth displacement of the fault wings in shear creep mode (RU, patent No. 2273035, G01V 9/00, 2006).

The disadvantage of this method is the low efficiency of the impact on vast seismically dangerous areas, since only local fragments of seismically active tectonic faults are exposed.

Closest to the technical nature of the present invention is a method of removing elastic energy in stressed media to prevent earthquakes, isolating the location of stressed media, pumping fluid into stressed media at time intervals corresponding to the expansion of stressed media due to the influence of lunar-solar tides, additional vibration to, during and after injection of fluid within stressed media with an intensity exceeding the intensity of the microseismic background, and Merenii horizontal and vertical displacements of the earth's surface tension among which are the residual strains and judgment in magnitude of the deformations of the magnitude of a previous elastic energy in the strained medium (RU, patent №2289151, G01V 9/00, 2006).

The disadvantage of this method is the low probability of preventing catastrophic earthquakes in vast seismic hazardous areas, since this method only produces a local impact on stressed massifs of rocks, which allows to reduce elastic stresses only in a relatively small area of the earth's crust, as well as low efficiency of the applied effects (vibration and liquid injection) due to the influence of filtration potentials. In addition, the application of this method requires large material costs.

The present invention solves the problem of increasing the efficiency of the removal of elastic stresses in the earth's crust. The technical result is to increase the likelihood of preventing catastrophic earthquakes by removing contact potentials, potentials arising in dry rocks as a result of crack formation and friction during creep, filtration potentials in fluid-containing rocks, leading to a decrease in normal stresses, a decrease in friction on cracks, fractures and in contact areas structural elements of the earth's crust at different levels of the hierarchical structure and to reduce the shear strength of rock masses.

The technical result is achieved in a method of relieving elastic stresses in the earth's crust to prevent catastrophic earthquakes, including dividing the study area into cells, determining in each cell the rate of seismotectonic deformations that characterizes the background value, followed by determining the average background speed of seismotectonic deformations ν _b for all cells, installation in the study area of at least one emitter of electromagnetic pulses, irradiation of the earth's crust is electromagnetic and pulses, determining the rate of seismotectonic deformations in each cell during irradiation and the ratio of this speed to the corresponding background value for this cell, followed by determining the average value of the ratio of velocities for all cells, identifying zones of increased concentration of elastic stresses with respect to the ratio of velocities exceeding the average value, additional irradiation of the selected zones with electromagnetic pulses with determination of the seismotectonic deformation rates ν (t) until the condition: ν (t) ≤ν _b , determination of the average rate of seismotectonic deformations over the entire exposure time ν _e and the exposure time t _e , determination of the magnitude of the removed elastic stresses in the earth's crust from the relation

Δσ = μ (ν _e -ν _b ) t _e ,

where ν _e is the average rate of seismotectonic deformations over the entire exposure time, 1 / year,

ν _b is the average background rate of seismotectonic deformations before irradiation, 1 / year,

t _e is the exposure time, year,

µ is the shear modulus adopted for the corresponding rocks, N / m ² .

Distinctive features of the proposed method for relieving elastic stresses in the earth's crust to prevent catastrophic earthquakes are the breakdown of the study area into cells, determination of the rate of seismotectonic deformations in each cell, which characterizes the background value, the subsequent determination of the average background velocity of seismotectonic deformations ν _b for all cells, and irradiation of the earth's crust by electromagnetic pulses, determination of the rate of seismotectonic deformations in each cell during irradiation I and the ratio of this velocity to the background value corresponding to a given cell with the subsequent determination of the average value of the ratio of velocities for all cells, the identification of zones of increased concentration of elastic stresses with respect to the velocity ratio exceeding the average value, the additional irradiation of the selected zones with electromagnetic pulses with the determination of the seismotectonic strain rates ν ( t) to satisfy the condition: ν (t) ≤ν _b, the definition of average speed of seismotectonic deformations of all time exposure ν _e and time of radiation t _e, determination of the captured elastic stresses in the crust of the above relationship.

The breakdown of the study area into cells is necessary for the localization of zones of increased concentration of elastic stresses. The determination of the rate of seismotectonic deformations in each cell, which characterizes the background value, is necessary to assess the changes in velocities during irradiation. The determination of the average background velocity of seismotectonic deformations ν _b for all cells is necessary for comparison with the current values of the rate of seismotectonic deformations during irradiation. Preliminary irradiation of the earth's crust with electromagnetic pulses is necessary to assess the concentration of elastic stresses within the study area. The determination of the rate of seismotectonic deformations in each cell during irradiation and the ratio of this velocity to the corresponding background value for this cell, followed by the determination of the average value of the ratio of velocities for all cells, is necessary to identify zones of increased concentration of elastic stresses. The identification of zones of increased concentration of elastic stresses by exceeding the velocity ratio in the cells of the average value of the rate of seismotectonic deformations is necessary for the spatial localization of zones of additional exposure to electromagnetic pulses and to control changes in their stress-strain state. Irradiation of the selected zones with electromagnetic pulses with the determination of the seismotectonic deformation rates ν (t) before the condition: ν (t) ≤ν _{b is} necessary to remove contact potentials, potentials arising in dry rocks as a result of crack formation and friction during creep, filtration potentials and strength reduction rocks, thereby initiating the activation of weak seismicity, which allows increasing the rate of seismotectonic deformations and causing intense release of the potential accumulated in the earth’s crust ialnoy elastic strain energy in the form of an intense flow of relatively weak earthquakes and thereby reduce the level of compressive stress. The determination of the average rate of seismotectonic deformations over the entire irradiation time ν _e and the irradiation time t _{e is} necessary to calculate the magnitude of the elastic stresses taken during irradiation. The above ratio is necessary for the numerical determination of the magnitude of the elastic stresses taken during irradiation in the earth's crust.

A method of relieving elastic stresses in the earth's crust to prevent catastrophic earthquakes is illustrated in the drawing, which shows the change in the speed of seismotectonic deformations before, during and after irradiation of the earth's crust by electromagnetic pulses throughout the study area (a), within the central (b) and southern (c) zones of increased concentration of elastic stresses.

A method of relieving elastic stresses in the earth's crust to prevent catastrophic earthquakes is as follows.

Break down the study area into cells. In each cell, the seismotectonic deformation rates are determined, which characterize the background value and the average background seismotectonic deformation rate ν _b for all cells. At least one emitter of electromagnetic pulses is installed in the study area. Irradiate the earth's crust with electromagnetic pulses. The seismotectonic deformation rates in each cell during irradiation and the ratio of this speed to the background value corresponding to the given cell are determined with the subsequent determination of the average value of the ratio of the velocities for all cells. Zones of increased concentration of elastic stresses are revealed in relation to velocities exceeding the average value. Additionally, the selected zones are irradiated with electromagnetic pulses with the determination of the seismotectonic deformation rates ν (t) until the condition: ν (t) ≤ν _b . The average seismotectonic deformation rates for the entire exposure time ν _e and the exposure time t _{e are} determined. The magnitude of the removed elastic stresses in the earth's crust is determined from the relation

Δσ = μ (ν _e -ν _b ) t _e ,

where ν _e is the average rate of seismotectonic deformations over the entire exposure time, 1 / year,

ν _b is the average background rate of seismotectonic deformations before irradiation, 1 / year,

t _e is the exposure time, year,

µ is the shear modulus adopted for the corresponding rocks, N / m ² .

A specific example of the method of removing elastic stresses in the earth's crust to prevent catastrophic earthquakes.

The study area, which was selected as one of the most seismic hazardous areas of Central Asia with an area of 120 × 210 km, having a complex geological structure, a strongly intersected mountainous terrain and a high level of seismic activity A ₁₀ = 2.1, was divided into cells with an area of 50 km ² . In each cell, the seismotectonic deformation rates ν _b (x, y) characterizing the background values and the average background seismotectonic deformation rate ν _b were determined (table). A map of their spatial distribution was constructed. The rate of seismotectonic deformations was determined according to a well-known method (B.V. Kostrov, Mechanics of the source of a tectonic earthquake. M .: Nauka, 1975, 174 pp.): V-seismotectonic deformation of a cell released during Δt = tt ₀ due to earthquakes , was determined from catalog data using the ratio

and the rate of seismotectonic deformation in this time interval was estimated as

ν = ε (t) / Δt,

- скалярный сейсмический момент i-го землетрясения, время возникновения которого t_i лежит в интервале t₀<t_i≤t, N - число таких землетрясений, µ - модуль сдвига, принятый равным 2.65·10¹⁰ Н/м².where t ₀ is the time of the beginning of observations, t is the current time,

is the scalar seismic moment of the i-th earthquake, the time of occurrence of which t _i lies in the interval t ₀ <t _i ≤t, N is the number of such earthquakes, µ is the shear modulus, taken equal to 2.65 · 10 ¹⁰ N / m ² .

по энергетическим классам землетрясений использовалось известное корреляционное соотношение (Раутиан Т.Г., Халтурин В.И., Закиров М.С. и др. Экспериментальные исследования сейсмической коды. М.: Наука, 1981, 142 с.). Эффективный объем каждой из рассматриваемых ячеек оценивался по совокупности землетрясений как V=4·δ_x·δ_y·δ_z, где δ_x, δ_y и δ_z - среднеквадратичное рассеяние координат гипоцентров по осям X, Y и Z. Затем на исследуемой территории установили один излучатель электромагнитных импульсов. В качестве излучателя электромагнитных импульсов был использован электрический диполь с разносом электродов 3 км и сопротивлением 1.5 Ом. Может быть использован в качестве излучателя магнитный диполь. Данный излучатель был установлен в центральной части исследуемой территории. В качестве источника использовался магнитогидродинамический (МГД) генератор. При запуске генератора ток в диполе достигал 1.5 кА, длительность электромагнитных импульсов - 2.0-2.5 с, а их энергия составляла 6.7-8.5 МДж. Затем было проведено облучение земной коры электромагнитными импульсами. По изложенной выше методике были определены скорости сейсмотектонических деформаций ν_e(x,y) в каждой ячейке во время облучения, отношения этой скорости к соответствующему для данной ячейки фоновому значению ν_b(х,y) и определено среднее значение этого отношения по всем ячейкам. По отношению скоростей ν_e(x,y)/ν_b(x,y), превышающих среднее значение, были выявлены зоны повышенной концентрации упругих напряжений. Одна из зон располагалась в центре исследуемой территории, а другая - в ее южной части. После чего было проведено дополнительное облучение выделенных зон электромагнитными импульсами с помощью МГД-генератора, во время которого для каждой из этих зон определялись текущие значения скорости сейсмотектонических деформаций ν(t) и строились их графики. Дополнительное облучение проводилось до выполнения условия: ν(t)≤ν_b, т.е. до того момента, когда скорость сейсмотектонических деформаций ν(t) становится равной или меньшей фонового значения скорости сейсмотектонических деформаций ν_b. После чего дополнительное облучение было прекращено. Время облучения составило 39 месяцев, в течение которого было проведено около 40 сеансов облучения. После завершения этих работ в течение некоторого времени определялись скорости сейсмотектонических деформаций. Зависимость скорости сейсмотектонических деформаций от времени ν(t) для всей исследуемой территории приведена на чертеже (а). Периоды облучения показаны вертикальными линиями. До облучения скорость сейсмотектонической деформации имеет относительно низкое значение. Сразу же после начала облучения скорость резко возрастает. После облучения - скорость снижается. На чертеже (б) и (в) приведены зависимости скорости сейсмотектонических деформаций от времени для выявленных зон повышенной концентрации упругих напряжений. Скорости сейсмотектонических деформаций во время облучения в этих зонах значительно выше.For determining

according to the energy classes of earthquakes, the well-known correlation relation was used (Rautian T.G., Khalturin V.I., Zakirov M.S. et al. Experimental studies of seismic codes. Moscow: Nauka, 1981, 142 pp.). The effective volume of each of the cells under consideration was estimated from the totality of earthquakes as V = 4 · δ _x · δ _y · δ _z , where δ _x , δ _y and δ _z are the mean square dispersion of the coordinates of the hypocenters along the X, Y, and Z axes. Then, in the study area installed one emitter of electromagnetic pulses. An electric dipole with an electrode spacing of 3 km and a resistance of 1.5 Ω was used as an emitter of electromagnetic pulses. A magnetic dipole can be used as a radiator. This emitter was installed in the central part of the study area. A magnetohydrodynamic (MHD) generator was used as a source. When the generator was started, the current in the dipole reached 1.5 kA, the duration of electromagnetic pulses was 2.0–2.5 s, and their energy was 6.7–8.5 MJ. Then, the earth's crust was irradiated with electromagnetic pulses. According to the method described above, the seismotectonic deformation rates ν _e (x, y) in each cell during irradiation, the ratio of this speed to the background value ν _b (x, y) corresponding to the given cell, were determined and the average value of this ratio for all cells was determined. By the ratio of the velocities ν _e (x, y) / ν _b (x, y) exceeding the average value, zones of increased concentration of elastic stresses were identified. One of the zones was located in the center of the study area, and the other in its southern part. After that, additional irradiation of the selected zones with electromagnetic pulses was carried out using an MHD generator, during which the current values of the seismotectonic deformation velocity ν (t) were determined for each of these zones and their graphs were constructed. Additional irradiation was carried out before the condition: ν (t) ≤ν _b , i.e. until the moment when the seismotectonic deformation rate ν (t) becomes equal to or lower than the background value of the seismotectonic deformation rate ν _b . After which the additional exposure was stopped. The irradiation time was 39 months, during which about 40 irradiation sessions were conducted. After the completion of these works, the rates of seismotectonic deformations were determined for some time. The time dependence of the seismotectonic deformation rate ν (t) for the entire study area is shown in drawing (a). The irradiation periods are shown by vertical lines. Prior to irradiation, the rate of seismotectonic deformation is relatively low. Immediately after the start of irradiation, the speed increases sharply. After irradiation, the speed decreases. The drawing (b) and (c) shows the dependence of the speed of seismotectonic deformations on time for the identified zones of increased concentration of elastic stresses. The rates of seismotectonic deformations during irradiation in these zones are much higher.

The table shows the numerical values of the rates of seismotectonic deformations (10 ^-8 / year) before (ν _b ), after (ν _a ) and during (ν _e ) irradiation of the crust, the removed elastic stresses (Δσ) and the released elastic deformations (Δε) in percent of the known values of ultimate strain (4.7 · 10 ^-5 ).

Table Region ν _b ν _a ν _e Δσ, bar * Δε,% whole territory 2.42 2.35 38.81 0.351 2.82 central zone 9.51 1.58 182.77 1.670 13.41 south zone 2.40 1.95 88.78 0.832 6.69 * 1 bar = 10 ⁵ Pa.

The table shows that during irradiation of the earth's crust, the rates of seismotectonic deformations in the study area increase by 16 times, and in the identified zones of increased concentration of elastic stresses - by 19-37 times. The greatest growth is observed within the zone located in the central part of the study area. The table also shows that after irradiation, strain rates in these areas become lower than before it begins, which indicates the release of elastic stresses in the earth's crust due to the intense release of elastic deformations during irradiation.

Then, the average seismotectonic deformation rates for the entire irradiation time ν _e and the irradiation time t _e were determined, and the values of the removed elastic stresses in the earth's crust were determined from the relation

Δσ = μ (ν _e -ν _b ) t _e ,

where ν _e is the average rate of seismotectonic deformations over the entire exposure time, 1 / year,

ν _b is the average background rate of seismotectonic deformations before irradiation, 1 / year,

t _e is the exposure time, year,

µ is the shear modulus adopted for the corresponding rocks, N / m ² .

The above ratio is obtained from Hooke’s law by substituting the strain, which is defined as the difference between the strain released during the total time of irradiation and equal to the product of the average speed and time (ν _e · t _e ) and the strain that should have been released during the same time at a constant speed (ν _b t _e ).

The obtained values of the removed elastic stresses are presented in the table, from which it can be seen that as a result of irradiation in the identified areas, the elastic stresses decreased by 0.8-1.7 bar, which in terms of deformation is 7-13% of the known values of the ultimate strains composing the Earth rock bark. This led to a decrease in elastic stresses in the earth's crust below critical values and prevented the occurrence of a strong (with magnitude M _w = 5.6) earthquake.

The proposed method of relieving elastic stresses in the earth's crust to prevent catastrophic earthquakes allows you to remove excess elastic stresses in the earth's crust by increasing the rate of release of seismotectonic deformations and, accordingly, their potential energy, as a result of the initiation of an intense flow of relatively weak earthquakes by electromagnetic pulses, has a high efficiency of removing excess elastic elastic earthquakes stresses over large areas, and can also be used to support seismic safety of critical facilities. This method is environmentally friendly, can be carried out using relatively compact mobile equipment and requires relatively low costs.

Claims (1)

A method of relieving elastic stresses in the earth's crust to prevent catastrophic earthquakes, including dividing the study area into cells, determining the velocity of seismotectonic deformations in each cell, which characterizes the background value, followed by determining the average background velocity of seismotectonic deformations ν _b for all cells, installing them in the study territory, at least one emitter of electromagnetic pulses, irradiation of the earth's crust with electromagnetic pulses, determining the speed of ismotectonic deformations in each cell during irradiation and the ratio of this velocity to the corresponding background value for this cell, followed by determining the average value of the ratio of velocities for all cells, identifying zones of increased concentration of elastic stresses with respect to velocities exceeding the average value, additional irradiation of the selected zones with electromagnetic pulses the definition seismotectonic deformation velocity ν (t) to satisfy the condition: ν (t) ≤ν _b, determining an average seismic velocity tectonic deformations for the time of irradiation and ν _e t _e irradiation time, determination of the captured elastic stresses in the earth crust from the relation:
Δσ = μ (ν _e -ν _b ) t _e ,
where ν _e is the average rate of seismotectonic deformations over the entire exposure time, 1 / year;
ν _b is the average background rate of seismotectonic deformations before irradiation, 1 / year;
t _e is the exposure time, year;
µ is the shear modulus adopted for the corresponding rocks, N / m ² .