RU2738589C1 - Method for determining tsunami hazard - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: invention relates to methods of seismic microzoning and can be used to detect the possibility of catastrophic events. According to the disclosed method, the analysed and reference observation points are placed on sections with different engineering-geological conditions. Seismic vibrations from earthquakes from potentially dangerous and other focal zones are recorded at said observation points. Dynamic parameters of seismic vibrations and their variations on each of the investigated observation points relative references in a given frequency range are determined. Further, three-component detection of seismic vibrations is carried out on profile network which is orthogonal and directed on the potentially dangerous focal zones. Ocean-bottom seismographs with broadband 0.003–20 Hz seismic channels are also placed on the continental slope and shelf along foot of the continental slope. Said seismographs are used to record tsunami wave pressure at the bottom at frequencies of 0.003–0.01 Hz. Recorded signals are transmitted over a hydroacoustic communication channel to reference points. At places where the ocean-bottom seismographs are installed, time variations of the geomagnetic field are also determined by measuring parameters of the gravitational and magnetic fields. Additionally, tidal oscillations of the sea surface are recorded by measuring wave height and direction with subsequent calculation of phase velocities of waves moving from the epicentre of the underwater earthquake towards the coast for different types of wave motions, wherein external forces of tidal potential, variable atmospheric pressure of wind intensity field and hydrostatic pressure are taken into account along the wave propagation path. According to linear scales sea bottom motions recorded by means of quartz sensors at deep seismic stations determine sizes of generating wave changes by initial parameters and/or interpolation-difference method. Measurements of wave height and direction with subsequent calculation of phase velocities of waves in open ocean are performed by standard radio altimeters installed on flight aircrafts. Tsunami wave forecast is made based on two isolated solitary waves in the form of hills following one after another with a period of oscillations from 15 to 60 minutes, and inclination values for selected waves, wherein if values of inclinations for 2–3 cycles exceed 4–5 ang. sec, then said wave is defined as tsunami wave. On the reference points, the Love and Rayleigh waves are selected, from which free gravity waves are determined by increasing the spectral density when approaching the shore in the low-frequency region, which serve as a signal on the approach of tsunamis. At the reference points, the ocean level variations are also simulated, caused by atmospheric disturbances with the tsunami signal on the shelf taking into account the inhomogeneous shoreline and in open ocean against background of natural long-wave noise with separation of long waves, for which there is a resonance reflection effect, including solitary waves in the form of hills with period of oscillations from 15 to 60 minutes.

EFFECT: technical result is broader functional capabilities.

5 cl

Description

The invention relates to the organization of security measures for coastal-based facilities located in seismically active regions, and can be used to alert about tsunami waves.

Known methods and systems for warning about tsunami waves in the ocean (patents RU No. 2276388 C1, 10.05.2006 [1], RU No. 2238574 C1, 20.10.2004 [2], JP No. 5072346 A, 26.03.1993 [3], RU No. 2270464 C1, 20.02.2006 [4], RU No. 2339977 C2, 27.11.2008 [5]), intended for early warning of tsunami and organized on a permanent basis registration of tsunami waves by bottom stations in the open deep ocean and similar to the DART system in the USA with Sides of the Pacific Ocean The main element of this system is bottom stations, which are complex structures consisting of a bottom unit with a pressure fluctuation recorder and a surface radio beacon for data transmission via satellite, interconnected by a multi-kilometer cable, as well as monitoring and control units. The stations constantly record the underwater situation and transmit data over a radio channel to the satellite.

The disadvantage of these seabed stations and the system as a whole is their complexity in manufacturing, laboriousness in setting up seabed stations in the ocean, keeping them in operation, and the high cost of manufacturing seabed stations and operating the system. In addition, the multi-element nature of the system, long-term operation in conditions of interference in the form of waves, wind, precipitation, cable twitching lead to unreliability of the system, which for the chosen scheme can only be compensated for by increasing the number of bottom stations in the observation area.

In the well-known technical solution [5], a significant simplification of the method for registering tsunami waves and notification of them, simplifying the design of bottom stations, reducing the cost of their manufacture and operation of the system as a whole is proposed. In contrast to the known methods using bottom stations, which are difficult to manufacture and operate and unreliable due to the multi-element structure, in the proposed technical solution [5], to provide early warning of a tsunami, one-time bottom stations are used, equipped with a recorder of pressure fluctuations at frequencies, typical for tsunami waves, and a unit with a radio transmitter that detaches from the bottom unit of the station when a signal exceeds a certain level and floats to the water surface to transmit data via satellite.

The specificity of the method is the autonomous operation of bottom stations in standby mode far from the coast at depths of the ocean floor 4-5 km with the registration of pressure waves at frequencies in the range of 0.001-0.002 Hz. Based on the mechanism of formation of tsunami waves (Ch. Drake et al. The ocean itself and for us. M .: "Progress", pp. 143-145), their height on the water surface for dangerous destructive tsunami waves is several meters at wavelengths of more than 100 m, which leads to a pressure at the bottom significantly exceeding, up to 1000 times, the natural ambient noise of the ocean in the specified frequency band (EE Gossard. Spectra of atmospheric scalas. J. Geoph. Res., 1960, v. 65, No. 10, 3339-3351).

Based on the considered conditions, the bottom station should be insensitive and work on the ocean floor in a standby mode for a significant time - up to 10 years or more, typical for the intervals of wave occurrence. The station should consist of two units, mechanically connected to each other and autonomous on power supply: a radio transmitter unit and a unit that registers pressure fluctuations in the specified frequency band, characteristic of a tsunami, and serves as the station's bottom anchor. When registering fluctuations exceeding a certain level, characteristic of a destructive tsunami, the station block with a radio transmitter should automatically disconnect from the bottom station and float to the water surface, after which it transmit the tsunami warning radio signal and the station coordinates via the satellite. Both blocks then cease to exist, which is economically feasible, given the long period of continuous operation of the station.

To ensure a quick ascent of the unit with a radio transmitter, which is important for timely warning of a tsunami, it must have a sufficiently large lifting force, and the material of its body must be transparent to radio waves. Considering that the block must withstand water pressure at depths of 4-5 km, the best known design solution for the block is a glass sphere consisting of two hemispheres. Such deep-sea spheres with a diameter of 30 cm have long been used in oceanographic studies, mainly as an element of buoyancy for deep-sea equipment. Their industrial production has been established. The expected estimated ascent time of such a sphere equipped with a radio transmitter is no more than an hour.

There are also known methods of seismic microzoning, which can be used to detect the potential onset of catastrophic phenomena mainly at sea (patents RU No. 1251694 C1, 30.07.1994 [6], RU No. 2346300 C1, 10.02.2009 [7], Bashilov I.P. and other Bottom geophysical observatories: design methods and applications - Scientific Instrumentation, 2008, vol. 18, No. 2, pp. 91-95 [8], application US No. 2006195263 A1, 31.08.2006 [9], patent RU No. 2436125 C1, 10.12.2011 [10]), and can also be used in solving the following fundamental problems: studying the structure of the earth's crust in the waters of the world ocean, studying the totality of the manifestation of geophysical fields in the zones of tectonic faults directly on the ocean floor, studying the state of the marine environment in the bottom zone and its interaction with tectonic processes, geophysical monitoring of complex hydraulic structures, operational assessment of the seismic and hydrodynamic state of areas and forecast potential seismic and environmental impacts; and early warning of earthquakes and tsunamis. It is known that due to the tectonic features of the Earth, over 80% of all earthquakes occur under the bottom of the seas and oceans. At the same time, the seismological network is located almost entirely on the continents and some islands. Registration of remote strong sea earthquakes by ground seismographs leads to large errors in determining the magnitude and coordinates of hypocenters, weak sea earthquakes are practically not recorded. The strongest earthquakes with a magnitude of 8 or more, causing mainly catastrophic tsunami waves, are concentrated under the ocean floor near seismically active continental margins. In Russia, such areas are the coast of Kamchatka, the Kuril Islands and Sakhalin Island. At present, by means of a long-term seismological forecast, the places of expected strongest earthquakes in this region have been identified. These are the Avachinsky Bay of Kamchatka and the Bussol Strait between the Urup and Simushir islands of the South Kuriles. However, on the basis of long-term forecasts, the time of onset of such earthquakes is determined with an error of tens to hundreds of years. Known methods based on the use of deep-sea tsunami wave recorders installed along the protected coast measure the pressure or thickness of the water layer and must have a very high sensitivity. The height of a tsunami wave in the open ocean of 10 cm can increase many times in shallow water and pose a significant danger. Therefore, when set to a depth of, for example, 3 km, the recorders must have a sensitivity of at least 3 × 10 ^-5 .

This sensitivity is provided by quartz pressure meters. Bottom echo sounders are used to measure the thickness of the water layer. The most advanced tsunami observation and warning systems, containing hundreds of ground seismographs and deep-sea recorders, are available in the USA (DART, NOAA) and Japan (JAMSTEC). These systems have a high cost and complex software and mathematical apparatus for processing recorded signals. There is also a fundamental possibility of detecting tsunami waves using satellite observations. However, to ensure the required resolution in height and the time of sequential scanning of the earth or water surface, no worse than 10-15 minutes, it is necessary to launch several dozen satellites into orbits. In addition, to distinguish tsunami waves, which in the open ocean have a height of several centimeters, complex mathematical processing is required to eliminate interference in the form of wind and tidal waves, wind surges. The known methods and devices in the open sea for predicting the possibility of a tsunami can hardly be applied, since at significant distances (large source sizes) it is impossible to determine the nature of the bottom deformation, and a significant tsunami wave occurs only with vertical or inclined movements. False alarms lead to large material losses. In addition, the base of measurements and the orientation of the measuring instruments relative to the source play a significant role in increasing the accuracy of measuring the signals, by which the precursors of catastrophic phenomena are established. So, for example, the spacing of meters at high and equatorial latitudes by more than 10 kilometers when measuring electrical and magnetic components leads to large (up to 50%) errors in impedance measurements.

It is known that high mobility of the earth's crust is observed within the most dynamic structures of the bottom of the World Ocean, which are transition zones and mid-ocean ridges.

On mainland platforms (with some exceptions) and in the ocean floor, earthquakes are extremely rare and do not acquire destructive forces. At the same time, the seismicity of transition zones and mid-oceanic ridges is different. It is known that according to the depth of location, earthquake foci are divided into surface (hypocenter depth up to 60 km), medium focus (60-300 km) and deep focus (more than 300 km). All types of earthquakes are represented in the transition zones. In the mid-oceanic zones, only surface earthquakes were recorded. The strongest earthquakes are mainly confined to the transition zones, in the region of the middle ridges only single strong earthquakes were noted.

Disadvantages similar to the above methods and devices are also inherent in methods and devices designed for recording signals of seismic origin in marine conditions. In the known methods, the significant value of the error is due to the fact that the average field of signal propagation is used when processing the registered signals. At the same time, the maximum deviations of the real field from the mean differ precisely at the horizons of the maximum gradients. In this case, the real field differs sharply from the ideal model. Under the influence of external factors with the use of acoustic means of signal registration, a shadow zone is formed, located in a strip of 5-16 kilometers from the source. Moreover, its length in different directions is not the same and may differ by 5 times or more, and with an increase in the distance between the receiver and the signal source, the errors increase. For sea conditions up to 15 kilometers, they are within 2 dB, further, in the range from 15 to 30 kilometers, their sharp increase is observed up to 6 dB. Subsequently, in the interval from 30 to 60 kilometers, the error value monotonically increases to 7.5 dB.

The main method of preventing human casualties and reducing material damage is the evacuation of the population of coastal areas to high land areas, the withdrawal of ships from the coastal zone to the open sea and the adoption of a number of other operational measures. This can be done only with timely warning of the tsunami by the coastal services.

In the Pacific Ocean, the average depth of which is about 4 km, the tsunami speed is about 700 km / h. It is practically impossible to notice a tsunami in the open ocean using known methods and devices, since at a height of 1-2 m, the waves have a length of several tens to hundreds of kilometers.

In most studies, in the field of studying the processes of tsunami waves, it is assumed that the initial elevation of the free surface in the zone of the tsunami source does not exceed several meters, and the wave periods lie in the range from 2 to 200 minutes. (VL Chubarov. Numerical modeling of tsunami waves: dissertation for the title of Doctor of Physics and Mathematics: Novosibirsk, 2000 [11]).

Known methods and devices for detecting ocean long waves of the tsunami type, based on bottom hydrostatic pressure sensors and hydrophones for detecting underwater earthquakes (patents RU No. 2473930 C2, 09/29/2010 [12], RU No. 2435178 C1, 09/14/2010 [13], RU No. 2555498 C2, 14.10.2013 [14], RU No. 2339977 C2, 13.11.2006 [15], RU No. 2362190 C2, 04.05.2007 [16], RU No. 2455664 C1, 09.03.2011 [17], RU No. 2363963 C1, 15.04.2008 [18], RU No. 2349939 C1, 14.08.2007 [19], US No. 10422908, 24.09.2019 [20], Vinokurov LV Forecast and prevention of a tsunami strike / Mining information and analytical bulletin (scientific -technical journal), 2007, No. 7, pp. 242-248 [21] do not allow to unambiguously fix the parameters of ocean long waves, for example, measurements of the height and slopes of the water surface in hundreds and thousands of kilometers from the coast.

In addition, the known seismic methods are burdened with numerous and time consuming calculations.

Known methods and devices for detecting ocean long waves of the tsunami type based on the observation of reflected radio signals by radar stations (US patent No. 10042051, 04/27/2016 [22]) are mainly applicable in coastal areas and are unacceptable in the open ocean.

Known methods and devices for detecting ocean long waves of the tsunami type based on the observation of reflected GNSS radio signals by artificial earth satellites (Tsunami-Wave Parameter Estimation Using GNSS-Based Sea Surface Height Measurement, Kegen Yu, IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING, VOL. 53, NO. 5, MAY [23]) are far from practical implementation. Analysis of the state of affairs in the field of detection of ocean long waves of the tsunami type shows that to solve the problem, tsunami warning systems are traditionally built:

- mainly on the processing of seismic information;

- to detect tsunami waves in the open ocean, bottom hydrostatic pressure sensors are used - the DART system;

- radar stations are used to detect tsunami waves in the open ocean;

- to detect tsunami waves in the open ocean, the reflected GNSS signals received by spacecraft are used.

These methods are difficult and expensive to implement over large areas of ocean water areas.

In world practice, various types of domestic and foreign models of navigation equipment of consumers (NAP) of global navigation satellite systems (GNSS) such as GLONASS and GPS, as well as radio-Doppler meters for speed, drift angle and flight altitude of aircraft are successfully used. The preliminary studies carried out to ensure the use of modern radio doppler meters showed the fundamental possibility of their use for detecting ocean long waves of the tsunami type. For this purpose, it is proposed to carry out phase measurements and comparison of parameters of direct and reflected from the sea surface GNSS signals in the aircraft NAP. An analysis of the performance of flights on cross-polar routes (official Internet resource of the Federal Air Transport Agency: rusavia @ scaa.ru) showed that in January-December 2018, 18,672 flights were performed, and in January-February 2019, 3,088 flights were performed.

The task of the proposed technical solution is to expand the functionality of the known methods while increasing the reliability of the forecast.

The problem is solved due to the fact that in the method of determining the tsunami hazard, including the placement of the studied and reference points of observation in areas with different engineering and geological conditions, the registration of seismic vibrations from earthquakes from potentially dangerous and other source zones, the determination of the dynamic parameters of seismic vibrations and their variations in each studied observation point relative to the reference ones in a given frequency range of studies, in which three-component registration of seismic vibrations is additionally carried out along an orthogonal network of profiles oriented to potentially dangerous source zones, the pressure of tsunami waves on the bottom is additionally recorded at frequencies 0.003-0.01 Hz by means of bottom seismographs with broadband seismic channels 0.003-20 Hz, the recorded signals are transmitted via the hydroacoustic communication channel to the control points located in the studied areas, while the bottom seismographs are placed on on the continental slope and shelf along the foot line of the continental slope, when processing seismic vibrations, the temporal variations of the geomagnetic field are determined by measuring the parameters of the gravitational and magnetic fields at the installation sites of bottom seismographs, in contrast to the known technical solution [10], selected as a prototype, in the process registration of seismic vibrations with the determination of the epicenter of an underwater earthquake, in addition, tidal fluctuations of the sea surface are recorded by measuring the height and direction of waves with the subsequent calculation of the phase velocities of waves moving from the epicenter of an underwater earthquake towards the coast for different types of wave motions, while taking into account the external forces of tidal potential, variable atmospheric pressure of the wind strength field and hydrostatic pressure along the wave propagation path. At the same time, according to the measured linear scales of the movement of the seabed, recorded by means of quartz sensors at deep-sea seismic stations, the sizes of the wave changes that form in this case are determined by the method of initial parameters and / or interpolation-difference method, measuring the height and direction of waves with the subsequent calculation of the phase velocities of waves in the open ocean performed by means of standard radio altimeters installed on scheduled airplanes, the forecast of the occurrence of a tsunami wave is performed using two isolated solitary waves in the form of hills, following each other with an oscillation period of 15 to 60 minutes and the slope values for the selected waves, while if the slope values during 2-3 cycles will exceed 4-5 ang. sec, then this wave is defined as a tsunami wave, Levy and Rayleigh waves are distinguished at the control points, according to which free gravitational waves are determined by increasing spectral density when approaching the coast in the low-frequency region, which serve as a signal about the approach of a tsunami; additionally, modeling is performed at the control points ocean level fluctuations caused by atmospheric disturbances with the release of a tsunami signal on the shelf, taking into account an inhomogeneous coastline and in the open ocean against the background of natural long-wave noise with the release of long waves, for which the effect of resonant reflection occurs, including solitary waves in the form of hills with an oscillation period of 15 up to 60 minutes. New distinctive features are that they additionally register tidal fluctuations of the sea surface by measuring the height and direction of waves with the subsequent calculation of the phase velocities of waves moving from the epicenter of an underwater earthquake towards the coast for different types of wave motions, while taking into account the external forces of the tidal potential , variable atmospheric pressure of the wind strength and hydrostatic pressure along the wave propagation path and, at the same time, according to the measured linear scales of the seabed displacement, recorded by means of quartz sensors at deep-sea seismic stations, the sizes of the wave changes that form in this case are determined by the method of initial parameters and / or interpolation - difference method, measuring the height and direction of waves with the subsequent calculation of the phase velocities of waves in the open ocean is performed by means of standard radio altimeters installed on scheduled aircraft, the forecast of the occurrence of a wave c unami is performed on two isolated solitary waves in the form of hills, following each other with an oscillation period of 15 to 60 minutes and the slope values for the selected waves, while if the slope values exceed 4-5 angles during 2-3 cycles. sec, then this wave is defined as a tsunami wave, Levy and Rayleigh waves are distinguished at the control points, according to which free gravitational waves are determined by increasing spectral density when approaching the coast in the low-frequency region, which serve as a signal about the approach of a tsunami; additionally, modeling is performed at the control points ocean level fluctuations caused by atmospheric disturbances with the release of a tsunami signal on the shelf, taking into account an inhomogeneous coastline and in the open ocean against the background of natural long-wave noise with the release of long waves, for which the effect of resonant reflection occurs, including solitary waves in the form of hills with an oscillation period of 15 up to 60 minutes allow you to get an operational assessment of the seismic state of the areas under study with a reliable forecast of possible seismic events, as well as provide early warning of impending earthquakes and tsunamis.

In addition, it becomes possible to identify gravitational and magnetic anomalies in the study areas. This circumstance, when performing seismic studies on the continental shelf, makes it possible to use the proposed technical solution for identifying oil and gas bearing regions. Since many shelves are a continuation of the lowlands confined to large platform troughs or syneclises, the strata filling these troughs are inclined towards the shelf and reach their maximum thickness precisely within its limits. The large thickness of terrigenous sediments in oil and gas regions is a favorable condition for oil and gas content.

The known methods make it possible to achieve the technical result, which consists in increasing the reliability, only in an isotropic field, since the nature of the decrease in the intensity of the sound signal with distance from the source in a horizontally inhomogeneous field (especially in the ocean) differs sharply from the same dependence in an isotropic field. Mesoscale inhomogeneities of the ocean (fronts, rings) dramatically rearrange the sound field, causing fluctuations in signal intensity up to 5 dB when predicting their range (D) up to 10 km. Therefore, for effective forecasting of meteorological, hydrological and acoustic conditions in anomalous regions, it is necessary to clearly establish centers and boundaries, as well as to determine the parameters of disturbing formations. Uncertainty in the calculation of the sound field based on climatic data or the reference field is expressed in standard deviations of the real level from the reference level of 4-9 dB at D = 90 km, which corresponds to the error in predicting the expected range of hydroacoustic systems by 60-90%. The use of a single curve of the vertical distribution of the speed of sound for acoustic calculations is permissible only at short distances (up to 10 km), which is extremely rare in real conditions. The magnitude and direction (sign) of the horizontal gradient along the signal propagation path can be used to judge the degree of variability of the sound field intensity at the receiving horizon relative to a fixed source. For acoustic field calculations, the parameter is the sound velocity profile that exactly matches the actual profile at the source location. However, when using mode information, the root mean square profile, as a rule, does not coincide with the actual profile, which leads to additional random errors in the final result. The set of new features from the prior art has not been identified, which allows us to conclude that the proposed technical solution meets the criterion of patentability "inventive step". The proposed method is implemented by means of a device that includes both sensors and prototype devices [10], namely: a bottom seismograph consisting of sensors for weak seismic signals and sensors for strong bottom movements, a digital multichannel data storage device, a buffer memory, a recording and control unit, a hydroacoustic communication channel , a power source, a magnetic field sensor, a bottom gravimeter, a hydrophysical module, an optical measurement unit, an information storage facility, a hydrochemical measurement unit, a spectrum analyzer, a seismic acoustic unit, a hydroacoustic telecontrol unit, a cable communication line modem, a radioactive element control unit, a methane detection sensor, etc. and additional devices with industrial applicability.

These devices can be placed both in the case of autonomous bottom stations, and in the case of underwater deep-water observatories, for example, of the DONET type (see, for example, G.V. Smirnov, V.I. Eremeev, M.D. Ageev, etc. Means and methods of oceanological research. - M .: Nauka, 2005, Kovchin I.S.Autonomous oceanographic measuring instruments. - L .: Gidrometeoizdat, 1991, Modern bottom stations for seismic prospecting and seismological monitoring / Zubko Yu.N., Levchenko D. G., Ledenev V.V., Paramonov A.A. // Scientific instrument-making, 2003, volume 13, No. 4, pp. 70-82 [24-26]).

Acoustic seismic sensors can be used as measuring sensors for recording acoustic signals, proton or quantum variometers and magnetometers for measuring the electric and magnetic components of the natural electromagnetic field of the earth with the release of the magnetotelluric component against the background of interference with the separation of electric and magnetic sensors by Δr≤ (0.013 … 0.025) r, (where r is the distance between the receiver and the source). In this case, the selection of the magnetotelluric component against the background of interference is greatly simplified, since the interference in the electric and magnetic channels is caused by different sources (they are uncorrelated) due to the distance of the sensors by the value of Δr. At the same time, the magnetic components of the natural magnetic field are less than the electrical ones and depend on the nature of the geoelectric section far from horizontal inhomogeneities. As a magnetic field sensor, designed to measure the absolute value of the magnetic induction of the earth's field in sea areas up to depths of 6000 meters, a sensor with a range of the measured value of magnetic induction of 20,000-100,000 nT is used. The analogue is the SFSM type sea bottom magnetometer. To perform gravimetric measurements, a gravimeter can be used, which is a design of a forced-balanced accelerometer, in which the operating frequency is maintained in the zero position using a feedback mechanism, or a string gravimeter of the BGM-3 type. As sensors of the seismoacoustic unit, a three-component seismoacoustic sensor is used, which is designed to convert the third derivative of ground motion into an electrical signal in a frequency range of 20-1000 Hz, the dynamic range of which in a 1/3 octave band and with a central frequency of 30 Hz is at least 60 dB, as well as a seismic receiver of the CM-5 type (velocimeter), which includes three seismic sensors with a seismic signal recording frequency range of 0.003-20 Hz, a full dynamic range of at least 120 dB. A sensor with a range of up to 600 atm with a measurement error of 0.03% is used as a bottom pressure sensor.

The hydroacoustic communication channel provides a range of up to 8000 m with a frequency range of signals from command carriers of 7-10 kHz.

The spectrum analyzer is designed to measure the Raman spectra of optical radiation as part of an underwater observatory. Raman spectra provide information on the composition of seawater.

The main technical characteristics of the spectrum analyzer are spectral range 0.52-0.78 µm, bandwidth 0.54 nm at 0.783 µm, positioning accuracy over the spectrum of 0.2 nm, number of spectral channels 4096.

The power supply is designed to provide autonomous power supply.

The radioactive elements control unit is designed to determine the content of gamma-emitting radionuclides (both technogenic and natural) in sea water.

The main technical characteristics of the unit are the range of registered energies 0.2-3.0 meV, the energy resolution along the cesium line is 13713%, the number of spectrum quantization levels is 256, the maximum number of counts in the channel is 65000, the maximum registration speed is not less than 1000 m / s.

The modem of the cable communication line is designed to transmit the registered parameters to the dispatch station.

The unit for registration and control of the underwater complex is designed to collect information from the sensors of the underwater observatory, link it to the exact time system, compress and transmit it over a cable communication line through a cable communication line modem or for recording information on a hard magnetic disk in an autonomous mode. The equipment of the hydroacoustic telecontrol unit is designed to control the operating modes and testing of the underwater observatory, as well as to send a signal for the ascent of beacons.

The hydroacoustic telecontrol unit equipment consists of two parts. The equipment, which is part of the control station and transmits control commands at a distance of up to 8 kilometers, is designed to control operation modes by transmitting hydroacoustic control commands, receiving receipts from the underwater observatory confirming the execution of commands, measuring the distance to the underwater observatory.

The underwater part of the hydroacoustic telecontrol equipment, located in the underwater observatory, provides reception and decoding of hydroacoustic commands for controlling the operating modes of the underwater observatory and the transmission of receipts confirming the execution of commands, as well as the issuance of commands for the emergence of radio beacons reporting the excess of certain parameters measured by the underwater observatory during work in standalone and cable mode. The hydrophysical module is designed to measure the following quantities:

- temperature,

- pressure, electrical conductivity,

- current velocity vectors (triaxial acoustic current meter),

- orientation of the observatory platform (roll-trim values).

The bottom seismograph is designed to provide continuous seismic monitoring of the seabed in a wide frequency and dynamic range. It includes sensors for weak seismic signals and sensors for strong bottom movements, a spatial orientation unit. The spatial orientation unit is designed to determine the exact position in space of all seismic sensors.

In this case, three-component seismic sensors (two horizontal and one vertical components) are used, designed to convert the ground motion velocity into an electrical signal in the appropriate dynamic and frequency ranges. The seismoacoustic unit is a three-component seismoacoustic sensor and is designed to convert the third derivative of ground motion into an electrical signal in the appropriate dynamic and frequency ranges. The main technical characteristics of the seismoacoustic unit: the number of seismoacoustic channels is 3, the frequency range is 20-1000 Hz, the dynamic range is in the 1/3 octave band and with a central frequency of 30 Hz not less than 60 dB, the amplitude of the output signal is not more than ± 10 V, the amplitude of the control signal at load current of 4 mA, no more than ± 5 V. As a magnetic field sensor, a TCM-2 electric compass module of the "Precision Navigation" company is used, which is a three-axis fluxgate magnetometer and an electronics unit made on a single board, which makes it possible to measure the values of the magnetic induction of the field land in sea areas to depths of 6000 m, in the range of the measured value of magnetic induction 20000 ... 100000 nT, with a reading error of ± 10 nT.

The block of hydrochemical measurements is a device that is designed to classify seawater pollution by spectral characteristics and molecular composition (Basic processes and devices of chemical technology: Design manual edited by Yu.I. Dytnersky. - M .: Chemistry, 1983, Chemist analytical complexes of Agilent Technologies (US), http://www.chem.agilent.com., Chemical-analytical complexes of SRI Instruments (US), http://www.perichrom.com., Chemical-analytical complexes of ZAO " Chromatek "(RU), http://www.chronomatec.ru).

The strongholds are made in the form of coastal structures or floating crafts (floating, stationary and moored platforms, ships). Strongpoint funds include:

- personal computer compatible with IBM PC,

- GPS satellite navigation system receiver,

- block of an autonomous hydroacoustic breaker,

- hydroacoustic telecontrol equipment.

The minimum configuration for a personal computer includes:

- processor - Pentium 166 MHz,

- RAM - 32 MB,

- SVGA card with 1 MB memory,

- additional board with two serial ports with FIFO memory (UART16550 - compatible).

They are used to process information received from an underwater observatory.

The software and mathematical support of the means for processing the registered information of the reference point is intended for checking all measuring channels of the underwater observatory and the registration and control unit via the RS-485 serial port, binding to the universal time system of the internal clock of the registration and control unit by means of the equipment of the hydroacoustic telecontrol unit and the GPS receiver, binding to geographic coordinates using the equipment of the hydroacoustic telecontrol unit, obtaining information on the results of test checks after the underwater observatory is installed on the bottom.

The algorithm of the main operating mode of the reference point is to provide communication between the underwater complex and the dispatch station, which is carried out through a deep-sea fiber-optic cable using the access method with time division of subscribers. Each underwater observatory has its own address. In this case, the network of dispatch stations operates in simplex mode. Up to 16 underwater observatories operating in an autonomous unattended mode can be simultaneously connected to one dispatch station via a deep-sea cable.

The number of measuring channels in each underwater observatory depends on the problem being solved at a specific location of the underwater observatory. In principle, the maximum number of digital measuring channels can be up to 30, and analog ones - up to 6.

The control computer of the reference point and the real-time software and mathematical support are designed to control the equipment of the underwater observatory, diagnose its malfunctions, receive data received from the underwater observatory, and place the received data on information storage devices. The functioning of the entire hardware and software complex is determined by a configuration file that is created by a special program and specifies the presence of underwater observatories, the type of geophysical channels used, channel parameters, as well as the presence or absence of time synchronization equipment (GPS receiver). When the registration program is launched, the configuration of the entire network of the underwater observatory is read, the time is referenced to Greenwich with an accuracy of several tens of microseconds, and corrections to the quartz frequency of the computer are calculated to maintain the functioning of the complex in the event of a short-term failure of the GPS receiver. Time synchronization is performed every second from the GPS receiver.

Synchronization is followed by interrogation, programming, synchronization and startup of equipment of individual underwater observatories. The status of the equipment of each underwater observatory is requested (its serviceability, availability of channels, serviceability of channels, etc.). In case of any problems, a corresponding message is displayed on the screen (it is also recorded in the operating protocol file). The registration and control unit 6 of the underwater observatory receives the program of operation for each measuring channel, the sampling frequency and the gain.

Before starting, each control and registration unit is synchronized with the time of the reference point computer (hereinafter, synchronization is carried out every 10 seconds). Synchronization takes into account the time it takes for the signal to travel from the dispatching station computer to the synchronized registration and control unit. After that, the registration and control unit starts up and starts collecting data from the measuring channels. The registration and control unit in each underwater observatory works independently and compresses and adds all information to the buffer memory. The control computer of the reference point cyclically requests the data on the signals registered by the sensors from the corresponding registration and control unit and, if available, receives them and writes them into its buffers in the random access memory. After accumulating a sufficient amount of data for the channel, they are rewritten to a file corresponding to the channel type. Typically, these files are located on another computer and are accessible over the local network, although for short-term experiments the system can be configured to use a local disk. In case of short-term interruptions in communication (up to 10 minutes), data is not lost, due to the presence of a sufficiently large buffer of its own for each registration and control unit. In the process of data exchange, the operator can calibrate any measuring channel that is part of the reference point network. In the event of abnormal situations (disconnection of communication with the underwater observatory, its breakdown, failure of individual channels, or restoration of the above), as well as some standard situations (occurrence of an event or start of calibration of the corresponding measuring channel), a message is displayed on the screen, including the GMT time of the occurrence of the situation, the names of the underwater observatories and the channel, as well as the message itself. Messages are also written to a 100-line buffer and a log file. The buffer can be viewed by the operator at any time. The measuring sensors of the underwater observatory, after its placement on the bottom, function for their intended purpose. The signals recorded by the sensors are recorded on the information storage means and during communication sessions are transmitted to the reference point, where a complete analysis of the assessment of the seismic and hydrodynamic state of the studied areas is performed, according to the results of which a forecast is made about possible seismic and environmental catastrophic events of a natural and man-made nature. Methane detection sensor, for example METS ("CAPSUM") type, which allows measuring methane concentration in the water column, is also included in the measuring instruments. The sensor is a semiconductor device, the principle of which is that the diffusion of hydrocarbon molecules from water through a special silicone membrane is transmitted to the sensor chamber. The adsorption of carbohydrate molecules on the active layer of the sensor leads to electronic exchange with oxygen molecules, thus changing the resistance of the active layer, which is converted into an output (measured) voltage. Main characteristics of the sensor:

- 10 μM silicone membrane,

- working depth 0-3500 m,

- working temperature 2-20 degrees C,

- measurement time 1-3 s,

- diffusion stabilization time up to 5 min depending on turbulence,

- input voltage 9-36 V,

- energy consumption 160 mA / h,

- output signal - analog 0-5 V and digital RS-485,

- methane 50 nmol / l - 10 μmol / l.

Additional sensors and devices include standard radio altimeters (RV) and radio Doppler speed and drift meters (RDISS) installed on airplanes flying along routes in tsunamigenic regions, as well as atmospheric and hydrostatic pressure sensors, wind parameters and sea level meters installed in coastal areas. By means of RV and RDISS, the flight altitude of the aircraft, the height of the sea wave (average wave height from the bottom to the top), the length of the sea wave in the direction of flight and in the place over which the aircraft is flying are determined. In this case, the height of the sea wave is judged by the difference between the maximum and minimum values of the amplitudes of the electromagnetic signal (the average height of the wave from the bottom to the top), the length of the sea wave in the direction of flight and in the place over which the plane flies is judged depending on the ratio of the wave height to the steepness of the wave, the period of excitement is determined depending on the ratio of the amplitude of the wave and the amplitude of acceleration in accordance with known algorithms (patent RU No. 2557999 C1, 27.07.2015). The block diagram of such a device, as in the prototype, includes an antenna, a transceiver, a height measurement unit, a Doppler frequency meter, a movement speed measurement unit, a computer for determining the wave height and phase velocity of waves, a unit for determining the direction of arrival of waves, a unit for determining the fluctuation component of the velocity, the unit for determining the angle of encounter with the wave, the unit for measuring the vertical displacements of the aircraft, the unit for evaluating the measurement errors.

Knowing the profiles of the agitated sea surface at the points of intersection of the radio beams with it and determining from them the time interval t of the sequential passage of the sea wave by the points of intersection of two radio beams with the sea surface, it is possible to calculate the angle of encounter with the wave.

It is known from the theory of sea gravitational waves that between the value of the phase velocity of the wave and its length λ _in there is a dependence V _f = √gλ _in / 2π (where g is the acceleration of gravity). Moreover, the value of λ _in is associated with the height of the wave h _{in a} relationship that depends on the type of approximation. According to the Register λ _in = 2.44 (h _in +1) ² . In turn, the wave height can be determined from the fluctuation component of the altitude meter readings, which, due to the normalness of the sea surface elevations, is also normal. In this case, the wave height h 3% probability _c3% = 5,3σ _in which _a σ - standard deviation of the measured elevations of the sea surface.

The essence of the method is as follows.

In areas with different engineering and geological conditions, the investigated and observation points are placed. At these observation points, seismic vibrations from earthquakes from potentially dangerous and other focal zones are recorded.

Determine the dynamic parameters of seismic vibrations and their variations in each investigated observation point relative to the reference in a given frequency range. Additionally, three-component registration of seismic vibrations is carried out along an orthogonal network of profiles oriented to potentially dangerous focal zones.

In addition, autonomous seabed stations or underwater observatories with measuring instruments are placed on the continental slope and shelf along the foot line of the continental slope.

By means of sensors of weak seismic signals measuring three components (horizontal, vertical and oblique components) in the range of 0.003-0.1 Hz, and sensors of strong bottom movements in the range of 0.01-20 Hz, which also measure three components, signals are recorded at the interface sea water - sea soil. When processing signals, the sum of the squares of the amplitudes, which has the maximum value for the signal of the expected structure, is used as the decisive statistics. Calculations are performed for each point in time to obtain the time dependence for each field. The presence of a maximum in it means the presence in the source of the expected structure of excitation of one or another field. The global maximum corresponds to the time of arrival of the aggregate received signal. When the value of the global maximum, equal to the average value between the amplitudes characterizing the levels of the state of the natural geophysical and hydrophysical fields, is reached, the possibility of a catastrophic phenomenon is judged. When processing seismic vibrations, the temporal variations of the geomagnetic field are determined by measuring the parameters of the gravitational and magnetic fields in the places where the bottom seismographs are installed. The recorded signals are used to establish the epicenter of an underwater earthquake. According to the characteristic linear scales of the bottom movement, the dimensions of the wave changes forming in this case are determined.

Then, the wave parameters are measured along the wave path from the epicenter towards the coast by means of a standard radio altimeter and a radio Doppler speed meter. When flying over the water surface, electromagnetic waves emitted by the radio altimeter are reflected from the water surface from the crest and base of the wave, which makes it possible to measure the wave height as well as the difference between the height of the crest and base. In addition, when the aircraft flight altitude changes according to the radio altimeter readings, in particular, the indicated altitude decreases by 0.5-1 m or more, taking into account the change in the slope of the average oceanic reflecting surface, it can be argued that a tsunami-type wave has been detected. By means of a standard radio-Doppler speed meter, the direction of wave movement is determined, tidal fluctuations of the sea surface are recorded by measuring the height and direction of waves with the subsequent calculation of the phase velocities of waves moving from the epicenter of an underwater earthquake towards the coast for different types of wave movements, while taking into account external forces tidal potential, variable atmospheric pressure of the wind strength field and hydrostatic pressure along the wave propagation path and, at the same time, according to the measured linear scales of the seabed displacement recorded by means of quartz sensors at deep-sea seismic stations, the sizes of the wave changes that form in this case are determined by the method of initial parameters and / or interpolation - by the difference method, measurements of the height and direction of waves with the subsequent calculation of the phase velocities of waves in the open ocean are performed using standard radio altimeters installed on scheduled aircraft x, the prediction of the occurrence of a tsunami wave is performed based on two isolated solitary waves in the form of hills, following each other with an oscillation period of 15 to 60 minutes and the slope values for the selected waves, while if the slope values exceed 4-5 during 2-3 cycles ang. sec, then this wave is defined as a tsunami wave, Levi and Rayleigh waves are distinguished at the reference points, according to which free gravitational waves are determined. As the spectral density increases when approaching the coast in the low-frequency region, which serve as a signal of an approaching tsunami, in addition, at the control points, the modeling of ocean level fluctuations caused by atmospheric disturbances is performed with the allocation of a tsunami signal on the shelf, taking into account the heterogeneous coastline and in the open ocean against the background of natural long-wavelength noise with separation of long waves, for which the effect of resonant reflection occurs, including solitary waves in the form of hills with an oscillation period of 15 to 60 minutes, allow you to quickly assess the seismic state of the studied areas with a reliable forecast of possible seismic events, as well as carry out early warning of impending earthquakes and tsunamis.

At ground stations for receiving and processing signals from the tsunami warning service, based on information received from the corresponding measuring sensors, the epicenter of an underwater earthquake is installed, which is notified by the corresponding technical centers, including crews of scheduled aircraft located in the region of the underwater earthquake.

After receiving information from the instruments for measuring the parameters of the ocean surface installed on scheduled airplanes, the measured signals are used to simulate ocean level fluctuations caused by atmospheric disturbances with the isolation of the tsunami signal on the shelf, taking into account the heterogeneous coastline and in the open ocean against the background of natural long-wave noise with the isolation of long waves for which the effect of resonant reflection occurs, including solitary waves in the form of hills with an oscillation period of 15 to 60 minutes, the forecast of the occurrence of a tsunami wave is performed using two selected solitary waves in the form of hills with an oscillation period of 15 to 60 minutes and the slope values for the selected waves, while if the values of the slopes for 2-3 cycles exceed 4-5 ang. sec, then this wave is classified as a tsunami wave.

When analyzing the identified tsunami wave, the following factors are taken from the recorded long waves: a magnitude of more than 7 on the Richter scale and the center of the earthquake is located under water, recorded solitary waves in the form of hills with a length of 10 to 100 km or more, while each such wave inevitably follows another is the same wave with an oscillation period of 15 to 60 minutes (VV Shuleikin. A short course in the physics of the sea. Hydrometeorological publishing house. L., 1959, pp. 105-108 [27]), the wave velocity in the open ocean is 500- 700 km, they register a Rayleigh wave - a harbinger of a tsunami, which propagates at a speed of about 20 times more than a tsunami wave, the distance between two solitary waves in the form of a hill is 100 km, the wave height is less than 1 m (Rabinovich A.B. Observations of a tsunami in the open Izvestiya RAN, series Physics of the atmosphere and ocean, 2014, vol. 50, No. 5, pp. 508-523 [28] Rabinovich AB Long gravitational waves in the ocean. St. Petersburg, Gidrometeoizdat, 1993, 326 p. . [29]).

In this case, if the measured parameters exceed the parameters for a calm sea by more than 75% for the first level and 50% for the second level, and the wave parameters tend to further increase synchronously, then the danger of a tsunami wave is more than 85%.

At the coastal stations, all registered signals are analyzed, with interference detection and classification by means of the useful signal correlator. The processing of the registered signals is carried out by means of the computing module of logical operations. First of all, waves of the Levy and Rayleigh type are distinguished, since when certain waves (Levy and Rayleigh) pass along the ocean floor, free gravitational waves appear in the water layer, which are more than an hour ahead of the arrival of tsunami waves. In this case, an increase in spectral density occurs when approaching the coast in the low-frequency region.

Rayleigh waves are observed far from the epicenter of the earthquake and are recorded by coastal bottom stations of the OBS-3 type. Further, long waves are distinguished in the range of 4-28 Hz, the phase velocities of which vary in the range of 350-700 m / s. Then free gravitational waves excited in the ocean by seismic surface waves are isolated. The velocities of surface gravity waves and internal gravity waves are different due to the density of the water environment. Waves with short-period fluctuations (0.1-8 hours) are associated with atmospheric disturbances or tsunamis. The difference in phase velocities for different types of wave motions leads to the physical separation of each of the types. Taking into account the external forces of the tidal potential, variable atmospheric pressure of the wind intensity field, and others. The group velocity of the waves is always less than the phase velocity in absolute value (Waves in the boundary regions of the ocean. Ed. By VV Efimov. L., Gidrometeoizdat, 1985, p. 280, p. 10 [30]). Insignificant fluctuations in sea level near the coast, due to these gravitational waves, can serve as a kind of natural signal about the approaching tsunami (Newspaper "St. Petersburg Vedomosti", February 25, 2020, p. 4, No. 33 (6631) [31]).

When processing all registered signals at coastal stations, the method of initial parameters and / or interpolation - difference method is used. Implementation of the proposed method of seismic microzoning will allow identifying long waves, assessing their parameters and using the data obtained in a shorter time frame and significantly increasing the reliability of the tsunami forecast.

The implementation of the device does not represent technical complexity, since the device is implemented on commercially available sensors and microelectronic elements, which allows us to conclude that the proposed technical solution meets the patentability condition "industrial applicability".

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Claims (5)

1. A method for determining the danger of a tsunami, including the placement of the investigated and reference points of observation in areas with different engineering and geological conditions, the registration of seismic vibrations from earthquakes from potentially dangerous and other focal zones, determination of the dynamic parameters of seismic vibrations and their variations in each investigated point observations relative to the reference ones in a given frequency range of studies, in which three-component registration of seismic vibrations is additionally carried out along an orthogonal network of profiles oriented towards potentially dangerous source zones, the pressure of tsunami waves on the bottom at frequencies of 0.003-0.01 Hz is additionally recorded by means of bottom seismographs with broadband seismic channels 0.003-20 Hz, transmit the registered signals via the hydroacoustic communication channel to the control points located in the studied areas, while bottom seismographs are placed on the continental slope and shelf along the bottom line of the continental slope, when processing seismic vibrations, the temporal variations of the geomagnetic field are determined by measuring the parameters of the gravitational and magnetic fields at the installation sites of bottom seismographs, characterized in that in the process of recording seismic vibrations with determining the epicenter of an underwater earthquake, tidal vibrations of the sea surface are additionally recorded by measuring the height directions of waves with the subsequent calculation of the phase velocities of waves moving from the epicenter of an underwater earthquake towards the coast, for different types of wave motions, while taking into account the external forces of the tidal potential, variable atmospheric pressure of the wind strength field and hydrostatic pressure along the wave propagation path, forecasting the occurrence of a wave tsunami is performed on two isolated solitary waves in the form of hills, following each other with an oscillation period of 15 to 60 minutes, and the slope values for the selected waves, while if the the inclinations for 2-3 cycles will exceed 4-5 ang. sec., then this wave is defined as a tsunami wave. 2. The method for determining the tsunami hazard according to claim 1, characterized in that, according to the linear scales of the seabed movement, recorded by means of quartz sensors at deep-sea seismic stations, the dimensions of the wave changes forming in this case are determined by the method of initial parameters and / or by the interpolation-difference method. 3. A method for determining a tsunami hazard according to claim 1, characterized in that measurements of the height and direction of waves with subsequent calculation of the phase velocities of waves in the open ocean are performed by means of standard radio altimeters installed on scheduled aircraft. 4. A method for determining a tsunami hazard according to claim 1, characterized in that Levy and Rayleigh waves are distinguished at the control points, according to which free gravitational waves are determined by increasing spectral density when approaching the coast in the low-frequency region, which serve as a signal about the approach of a tsunami. 5. The method for determining the tsunami hazard according to claim 1, characterized in that, in addition, at the control points, the simulation of ocean level fluctuations caused by atmospheric disturbances is performed with the separation of the tsunami signal on the shelf, taking into account the heterogeneous coastline and in the open ocean against the background of natural long-wave noise with the long wavelengths, for which the effect of resonant reflection occurs, including solitary waves in the form of hills with an oscillation period of 15 to 60 minutes.