JP6370760B2 - Earthquake prediction system - Google Patents

Description

  The present invention relates to an apparatus for detecting a disturbance generated in an ionosphere, and more particularly to an earthquake prediction system that predicts an earthquake using a generated disturbance.

  Conventionally, there have been devices that detect disturbances (disturbances in the ionosphere) that occur in the ionosphere to predict the occurrence of earthquakes. For example, there has been a method and apparatus for detecting disturbances generated in the E layer (altitude 90 to 130 km) of the ionosphere using very long wave (VHF) radio waves emitted from the ground. In a normal case where no disturbance occurs in the E layer, the VHF radio wave passes through the E layer and does not return to the ground. However, when disturbance occurs in the E layer, the VHF radio wave that reaches the E layer is scattered (reflected) by the disturbance of the E layer, and the VHF radio wave propagates out of line of sight (usually far away from the VHF radio wave). Is done. This conventional device emits VHF radio waves from the ground and detects the reflected VHF radio waves on the ground when the VHF radio waves are reflected by disturbance of the E layer (see, for example, Patent Document 1).

  There have also been systems that take advantage of the impact of ionospheric disturbances on existing very long waves (VLF) / long waves (LF). Specifically, this is a system that uses the VLF and LF radio waves transmitted from the ground to detect disturbances that occur in the lower part of the ionosphere (D layer: altitude 60-90 km) that occur before the earthquake at observation points on the ground. . This conventional system utilizes the fact that when a disturbance occurs in the ionosphere on the propagation path of a VLF or LF radio wave, an abnormality occurs in the intensity or phase of the received radio wave (see, for example, Patent Document 2).

Japanese Patent No. 2875398 Japanese Patent No. 4,867,016

  Since the VHF radio wave is easily affected by weather, the above-described apparatus for detecting the disturbance of the E layer may not be able to accurately detect the disturbance. Further, the D layer has an altitude of 60 to 90 km, and is closer to the ground than the E layer (altitude 90 to 130 km). For this reason, the D layer is susceptible to various electromagnetic waves from the ground. Further, the D layer is easily fluctuated due to the influence of solar flare. For this reason, it is necessary to remove noise due to the influence of solar flare, but it is difficult to remove noise, and it takes time and effort to remove noise, and disturbance may not be detected accurately.

  The present invention has been made in view of the above-described points, and an object of the present invention is to provide an earthquake prediction system capable of accurately detecting a disturbance generated in the ionosphere.

An embodiment of the earthquake prediction system according to the present invention is as follows.
First analysis means for performing a first analysis and determining whether a disturbance of the first layer in the ionosphere has occurred;
Second analysis means for performing a second analysis and determining whether or not a disturbance has occurred in the second layer higher than the first layer;
An earthquake occurrence prediction means for predicting the occurrence of an earthquake based on the determination result by the first analysis means and the determination result by the second analysis means,
The earthquake occurrence prediction means predicts that an earthquake will occur if it is determined by the first analysis means that a disturbance has occurred in the first layer ,
When it is determined by the first analysis means that a disturbance has occurred in the first layer, and when the second analysis means determines that a disturbance has occurred in the second layer, the first analysis means causes the first analysis to occur. Predicting that an earthquake with a greater magnitude will occur than when it was determined that there was a disturbance in the layer and the second analysis means did not determine that a disturbance had occurred in the second layer,
Predicting that an earthquake will not occur if the first analysis means does not determine that a disturbance has occurred in the first layer and the second analysis means determines that a disturbance has occurred in the second layer. It is characterized by.

  Disturbances generated in the ionosphere can be accurately detected.

It is a figure which shows the earthquake prediction system by this Embodiment. It is the schematic which shows the outline | summary of the earthquake prediction system by this Embodiment. It is a figure which shows the structure of the antenna used with the earthquake prediction system by this Embodiment. It is a flowchart which shows the measurement and transmission process of F layer of an ionosphere. It is a flowchart which shows the F layer disturbance analysis process of an ionosphere. It is a flowchart which shows the F layer disturbance analysis process of an ionosphere. It is the table | surface (A) which shows the example of a prediction table, and the table | surface (B) which shows the example of an occurrence probability table. It is a flowchart which shows the measurement and transmission process of D layer of an ionosphere. It is a flowchart which shows the process which analyzes the disturbance which arose in D layer and F layer of an ionosphere.

  Embodiments will be described below with reference to the drawings.

As shown in FIG. 1, the ionosphere monitoring device according to the present embodiment is
A passing radio wave receiving means (for example, a receiving system 200 described later) capable of receiving radio waves emitted from extraterrestrial celestial bodies and passing through the ionosphere, including artificial celestial bodies;
Judging means (for example, an analysis server 300 described later) for judging that the plasma density of the ionosphere has changed based on a change from the radio wave reception state to the non-reception state in the passing radio wave reception unit; Prepare.

  That is, the ionosphere monitoring device according to the present embodiment includes a passing radio wave reception unit and a determination unit. The passing radio wave receiving means can receive radio waves emitted from extraterrestrial bodies and passing through the ionosphere. Extraterrestrial celestial bodies include artificial celestial bodies such as artificial satellites that are artificially placed in outer space. The passing radio wave receiving means can receive radio waves when radio waves emitted from extraterrestrial bodies pass through the ionosphere. However, depending on the state of the ionosphere, radio waves may not pass through the ionosphere and may not receive radio waves. For example, when disturbance occurs in the ionosphere, radio waves may be reflected by the ionosphere, and the passing radio wave receiving means cannot receive such radio waves.

  The determining means determines that the plasma density of the ionosphere has changed based on a change from a state in which radio waves can be received (reception state) to a state in which radio waves cannot be received (non-reception state). When fluctuations occur in the plasma density of the ionosphere, disturbance occurs in the ionosphere and reflects radio waves. In such a case, since radio waves cannot be received, it can be determined whether or not the plasma density of the ionosphere has changed by detecting the reception state or non-reception state of radio waves.

The ionosphere monitoring device according to the present embodiment further includes
The passing radio wave receiving means receives radio waves in a frequency band that passes through or is reflected by the ionosphere according to the plasma density of the ionosphere.

  Radio waves emitted from extraterrestrial celestial bodies include radio waves of various frequencies. For example, radio waves having a frequency of 3 to 50 MHz are included. These radio waves include radio waves in a frequency band that passes through the ionosphere or is reflected by the ionosphere according to the plasma density of the ionosphere. The passing radio wave receiving means can determine whether or not the plasma density of the ionosphere has changed by targeting radio waves in such a frequency band.

The ionosphere monitoring device according to the present embodiment further includes
The passing radio wave receiving means is installed on the ground.

  Since the passing radio wave receiving means is installed on the ground, the direction of the extraterrestrial celestial body can be identified stably, and radio waves from extraterrestrial celestial bodies can be accurately received.

As shown in FIG. 1, the ionosphere monitoring device according to the present embodiment is
A passing radio wave receiving means (for example, a receiving system 200 to be described later) capable of receiving radio waves of a plurality of frequencies emitted from an extraterrestrial celestial body and passed through the ionosphere, including artificial celestial bodies;
Frequency classification means (for example, an analysis server 300 described later) for classifying the plurality of frequencies into a first frequency that could not be received by the passing radio wave reception means and a second frequency that could be received;
Critical frequency determining means (for example, an analysis server 300 described later) for determining a critical frequency that becomes a boundary between the first frequency and the second frequency;
Critical frequency storage means for storing the critical frequency (for example, analysis server 300 described later);
Critical frequency change detecting means (for example, analysis server 300 described later) for detecting that the critical frequency has changed with time based on the past critical frequency stored in the critical frequency storage means;
Ionosphere determining means (for example, analysis server 300 described later) for determining that the plasma density of the ionosphere has changed based on the determination that the critical frequency has changed with time by the critical frequency change detecting means; .

  That is, the ionosphere monitoring apparatus according to the present embodiment includes a passing radio wave receiving unit, a frequency classification unit, a critical frequency determination unit, a critical frequency storage unit, a critical frequency change detection unit, and an ionosphere determination unit.

  The passing radio wave receiving means can receive radio waves emitted from extraterrestrial bodies and passing through the ionosphere. Extraterrestrial celestial bodies include artificial celestial bodies such as artificial satellites that are artificially placed in outer space. The passing radio wave receiving means can receive radio waves when radio waves emitted from extraterrestrial bodies pass through the ionosphere. However, depending on the state of the ionosphere, radio waves may not pass through the ionosphere and may not receive radio waves. For example, when disturbance occurs in the ionosphere, radio waves may be reflected by the ionosphere, and the passing radio wave receiving means cannot receive such radio waves.

  For example, it is preferable that the ionosphere particularly targets the F layer. The radio wave is preferably a radio wave having a frequency of 3 to 50 MHz. In the daytime, the F1 layer (150 km to 220 km) and the F2 layer (220 km to 800 km) are separated into two layers, and at night, the F1 layer and the F2 layer are merged into a single F layer. As will be described later, the reception of radio waves is preferable at night to avoid the influence of various noises and the like. For this reason, in this Embodiment, it is preferable to make night F layer into object.

  The frequency classifying means includes a first frequency (including a first frequency band and a range of the first frequency area) that could not be received by the passing radio wave receiving means and a second frequency (second frequency band) that could be received. And the second frequency region). Radio waves emitted from extraterrestrial celestial bodies include radio waves of various frequencies. These radio waves include radio waves in a frequency band that passes through the ionosphere or is reflected by the ionosphere according to the plasma density of the ionosphere. Therefore, there are radio waves having a frequency that cannot be received by the passing radio wave receiving means (first frequency radio waves) and radio waves having a frequency that can be received by the passing radio wave receiving means (second frequency radio waves). The frequency classifying unit classifies the first frequency and the second frequency.

  The critical frequency determining means determines a frequency (critical frequency) that is a boundary between the first frequency and the second frequency. A frequency between the lowest frequency among the second frequencies classified by the frequency classification means and the highest frequency among the first frequencies can be set as a critical frequency. The lowest frequency that can be received by the passing radio wave receiving means may be the critical frequency, and the highest frequency that cannot be received by the passing radio wave receiving means may be the critical frequency.

  The critical frequency storage means stores the critical frequency determined by the critical frequency determination means. By storing the critical frequency, it can be stored as a history of the critical frequency, and the past transition of the critical frequency can be determined statistically.

  The critical frequency change detecting means detects that the critical frequency has changed with time based on the past critical frequency stored in the critical frequency storage means. For example, it is preferable to execute a statistical process using a past critical frequency stored in the critical frequency storage means and determine a past transition of the critical frequency. By comparing the past transition of the critical frequency with the latest critical frequency, it can be determined whether the critical frequency has changed over time. Since statistical processing is performed, it is possible to determine the past transition of the critical frequency by eliminating the influence of the critical frequency due to the season and the influence of noise, and whether or not the latest critical frequency has changed over time. Can be judged accurately.

  The ionosphere determining means determines that a change has occurred in the plasma density of the ionosphere based on the fact that the critical frequency change detecting means has determined that the critical frequency has changed with time. When fluctuations occur in the plasma density of the ionosphere, the ionosphere is disturbed and reflects radio waves. For this reason, the first frequency and the second frequency change with time, and the critical frequency changes with time. Therefore, it can be determined whether or not the plasma density of the ionosphere has changed by detecting that the critical frequency has changed with time.

Furthermore, as shown in FIG. 1, the earthquake prediction system according to the present embodiment
Comprising the ionosphere monitoring device described above,
A duration detecting means for detecting a duration in which the critical frequency continuously changes;
A statistical threshold value calculation means for calculating a statistical threshold value from the critical frequency stored in the critical frequency storage means;
Magnitude reference table storage means for storing a magnitude reference table in which a magnitude associated with the duration and the statistical threshold is defined;
Alert sending means for sending an alert according to the magnitude determined by the magnitude reference table.

  That is, the earthquake prediction system includes a duration detection unit, a statistical threshold calculation unit, a magnitude reference table storage unit, and an alert transmission unit.

  The duration detection means detects a duration in which the critical frequency is continuously changed. The statistical threshold value calculation means calculates a statistical threshold value from the critical frequency stored in the critical frequency storage means. The magnitude reference table storage means stores a magnitude reference table in which a magnitude associated with a duration and a statistical threshold is defined. The magnitude reference table is determined in advance by past measurements. Furthermore, the magnitude reference table is updated based on the occurrence of a new disturbance or earthquake. The alert sending means sends an alert according to the magnitude determined by the magnitude reference table.

Moreover, as shown in FIG. 1, the earthquake prediction system according to the present embodiment further includes
Alert transmission target table storage means for storing an alert transmission target table that defines a target for transmitting an alert based on the magnitude of the magnitude,
The alert transmission means refers to the alert transmission target table based on the magnitude of the magnitude, and determines a target for transmitting the alert.

  The earthquake prediction system further includes alert transmission target table storage means. The alert transmission target table storage unit stores an alert transmission target table that defines a target for transmitting an alert based on the magnitude of the magnitude.

  The alert transmission means refers to the alert transmission target table based on the magnitude of the magnitude and determines a target person who transmits the alert.

<< Overview of Earthquake Prediction System 100 >>
The earthquake prediction system 100 according to the present embodiment receives radio waves that reach the earth from the planet, particularly radio waves that reach the earth from Jupiter, and determines whether or not a disturbance has occurred in the F layer of the ionosphere. When it is determined that a disturbance has occurred in the F layer of the ionosphere, an alert is issued that an earthquake will occur in the near future in an area corresponding to the range in which the disturbance has occurred.

  When an earthquake occurs, charge fluctuations occur due to microcracks that are precursors of the earthquake. When the charge fluctuation reaches the ionosphere, the electron density (plasma density) of the ionosphere is changed, and the ionosphere is disturbed. So far, it is known that the magnitude of the earthquake is determined according to the degree of ionospheric disturbance.

  The earthquake prediction system 100 uses radio waves from celestial bodies, for example, planets, particularly radio waves from Jupiter. Specifically, radio waves of 3 to 50 MHz, preferably 3 to 30 MHz (so-called HF band radio waves) are received. Since a radio wave of 3 to 30 MHz is generally reflected by a disturbance generated in the F layer of the ionosphere, it is suitable for detecting the disturbance generated in the F layer. Note that even a frequency outside this range may be a radio wave that can detect the disturbance generated in the F layer.

  As described above, the earthquake prediction system 100 according to the present embodiment detects whether or not a disturbance has occurred in the F layer using radio waves having a frequency of 3 to 30 MHz. This 3-30 MHz radio wave is divided into two frequency bands. The first frequency band is a frequency band lower than a specific frequency (referred to as a critical frequency). The radio waves in the first frequency band are reflected by the F layer. Therefore, in this first frequency band, radio waves from the planet are reflected by the F layer, and thus cannot be received on the earth.

  On the other hand, the second frequency band is a frequency band higher than the critical frequency. The radio wave in the second frequency band passes through the F layer without being reflected by the F layer. Accordingly, in this second frequency band, radio waves from the planet can reach the earth and can be received on the earth.

  Thus, the critical frequency is a frequency indicating a boundary between the first frequency band in which the radio wave is reflected by the F layer and does not pass the radio wave, and the second frequency band in which the radio wave can pass through the F layer.

  Furthermore, when no disturbance occurs in the F layer of the ionosphere, the critical frequency is low, and when a disturbance occurs in the F layer of the ionosphere, the critical frequency gradually increases depending on the degree of the disturbance. That is, the first frequency band in which radio waves do not pass gradually spreads toward the high frequency side according to the degree of disturbance generated in the F layer of the ionosphere. Therefore, even in a frequency band in which radio waves can be received when no disturbance has occurred in the F layer of the ionosphere, there are frequency bands in which radio waves cannot be received due to disturbance in the F layer of the ionosphere. The earthquake prediction system 100 is a system for radio waves in such a frequency band.

  In the earthquake prediction system 100, first, radio waves of a predetermined frequency that can pass through the F layer of the ionosphere can be received on the ground. When radio waves of this predetermined frequency can be received on the ground, radio waves from the planet pass through the F layer of the ionosphere, so it can be determined that no disturbance has occurred in the F layer of the ionosphere. On the other hand, when radio waves of this predetermined frequency cannot be received on the ground, radio waves from the planet are reflected by the F layer of the ionosphere, and it can be determined that disturbance has occurred in the F layer of the ionosphere.

  More precisely, the occurrence of disturbance in the F layer is determined by obtaining the critical frequency. Specifically, for a plurality of frequencies, it is determined whether radio waves can be received from the planet, and the critical frequency is obtained. When the obtained critical frequency is low, it is determined that there is no disturbance in the F layer of the ionosphere and no earthquake occurs. On the other hand, when the critical frequency is high, it is determined that there is a disturbance in the F layer of the ionosphere and an earthquake occurs. The earthquake prediction system 100 is a system that predicts an earthquake by determining the critical frequency of the ionosphere for the F layer and determining the level of the determined critical frequency.

  FIG. 2 is a schematic diagram showing an outline of the earthquake prediction system 100. The earthquake prediction system includes a plurality of reception systems 200, an analysis server 300, and a distribution system 400. The receiving system 200, the analysis server 300, and the distribution system 400 are communicably connected to a network line 90 such as the Internet.

  The reception system 200 is installed at each of the observation points A to N. Observation points A to N are a plurality of points in a predetermined area, for example, the territory of Japan, and are suitable for receiving radio waves from the planet. By increasing the number of observation points, the occurrence of disturbance can be determined at a plurality of locations, and the prediction of the earthquake can be determined in more detail.

  The reception system 200 includes an antenna system 205, a receiver 250, and a control device 260. In the example shown in FIG. 2, a case where one receiving system 200 is installed at each of the observation points A to N is shown. Two or more receiving systems 200 may be installed at the observation point. For example, the number of reception systems 200 may be determined according to measurement conditions such as the number of radio wave frequencies to be received.

<Antenna system 205>
FIG. 3 is a diagram illustrating a configuration of the antenna system 205. The antenna system 205 includes a plurality of antenna devices 210. In the present embodiment, the antenna system 205 includes a first antenna device 210A and a second antenna device 210B. The first antenna device 210A and the second antenna device 210B have approximately the same configuration, and differences will be described later. Hereinafter, the first antenna device 210 </ b> A and the second antenna device 210 </ b> B are simply referred to as the antenna device 210 when it is not necessary to distinguish between them.

  The antenna device 210 includes a first wideband dipole antenna 212A and a second wideband dipole antenna 212B. These wideband dipole antennas 212A and 212B have the same configuration. By adopting a wideband dipole antenna, a wide range of frequencies can be received and the critical frequency of the ionosphere can be monitored. Hereinafter, when it is not necessary to make a distinction, it is simply referred to as a wideband dipole antenna 212.

  The wideband dipole antenna 212 has two wires 214a and 214b (elements) having conductivity. The two wires 214a and 214b have an elongated shape, for example, a length of about 10 meters.

  The two wires 214a and 214b are held by a plurality of non-conductive separators 216 so as to be spaced apart and parallel to each other. Separator 216 has a length of about 0.5 meters, for example. By holding the two wires 214a and 214b by the separator 216, the two wires 214a and 214b are arranged to be parallel to each other at an interval of about 0.5 meters.

  The first ends 218a of the two wires 214a and 214b are electrically connected. The second ends 218b of the two wires 214a and 214b are also electrically connected. In this way, the entire wideband dipole antenna 212 can function as a folded dipole antenna.

  A insulator 220a is provided at the first end 218a of the wires 214a and 214b. Similarly, insulators 220b are provided at the second ends 218b of the wires 214a and 214b. A support wire 222 is connected to each of the insulators 220a and 220b. By attaching the support wire 222 to two supports (not shown) such as iron pillars, the wideband dipole antenna 212 can be stretched between the two supports.

  A balun 224 is connected to the center of one of the wires 214a of the wideband dipole antenna 212. The balun 224 is provided with a connector to which a coaxial cable 226 (226A and 226B) can be connected. The balun can convert an electric signal in a balanced state (wideband dipole antenna 212) and an unbalanced state (coaxial cable 226).

<Fading cable 230>
A fading cable 230 is connected to the first wideband dipole antenna 212A. By connecting the fading cable 230 to the first wideband dipole antenna 212A, the wavelength shift of the first wideband dipole antenna 212A and the second wideband dipole antenna 212B can be corrected. Gender can be changed.

  In the present embodiment, fading cable 230 includes three fading cables 230a, 230b, and 230c having different lengths. For example, fading cable 230a is the shortest, fading cable 230b is longer than fading cable 230a, and fading cable 230c is the longest.

  Any one of the three fading cables 230a, 230b, and 230c is selected by the first coaxial switches 232a and 232b. The first coaxial switches 232a and 232b are controlled by a control signal output from the control device 260 described later. One of the three fading cables 230a, 230b, and 230c is selected in response to a control signal from the control device 260.

  As described above, in the present embodiment, radio waves are received from planets, particularly Jupiter. Since the earth is also a planet, it is necessary to consider the relative positional relationship between the earth and Jupiter, specifically, the revolution and rotation of Jupiter and the revolution and rotation of the earth. Since the direction of Jupiter varies depending on the season, by appropriately selecting one of the three fading cables 230a, 230b and 230c, the antenna system 205 can be made to have a favorable directivity for that season. Can be efficiently received.

  The first wideband dipole antenna 212A is connected to the mixer 234 via a fading cable 230 (230a, 230b or 230c). The second wideband dipole antenna 212B is directly connected to the mixer 234. By the mixer 234, the radio wave received by the first wideband dipole antenna 212A and the radio wave received by the second wideband dipole antenna 212B are combined and output to the second coaxial switch 236 as a received signal. be able to. By connecting the first wideband dipole antenna 212A and the second wideband dipole antenna 212B to the mixer 234, an array antenna can be configured.

  A second antenna device 210B having the same configuration as that of the first antenna device 210A is switchably connected to the second coaxial switch 236. The second antenna device 210B has at least one fading cable (not shown) having a length different from any of the three fading cables 230a, 230b, and 230c in the first antenna device 210A. The three fading cables 230a to 230c of the first antenna device 210A are switched to the second antenna device 210B by the second coaxial switch 236 when the directivity of the wideband dipole antenna 212 cannot be sufficiently realized. The directivity of the wideband dipole antenna 212 can be made appropriate by the fading cable of the second antenna device 210B.

  The length of the fading cable differs between the first antenna device 210A and the second antenna device 210B, and the other configurations are the same. The second antenna device 210B also includes a first wideband dipole antenna 212A and a second wideband dipole antenna 212B.

  The radio wave received by the first wideband dipole antenna 212A of the second antenna device 210B and the radio wave received by the second wideband dipole antenna 212B are combined into one as a received signal, and the second coaxial switching device. 236.

  As described above, the array antenna is configured by the first wideband dipole antenna 212A and the second wideband dipole antenna 212B. By using the array antenna, the amplitude of the radio wave can be amplified. In order to receive weak radio waves from the planet, the amplitude can be increased by superimposing the two radio waves.

  Furthermore, by using an array antenna, the antenna can have directivity. Since one antenna has no directivity and a wide range of directions in which radio waves can be received, it may be difficult to efficiently receive radio waves from a specific direction. By configuring the array antenna, the antenna can have directivity in the upward direction.

  In addition, since the radio wave source (Jupiter) is not in the upward direction but is in the vicinity of 70 ° to 80 ° above the south, the radio wave is shifted. For this reason, the deviation of radio waves can be corrected by tilting the directivity in an oblique direction. In the present embodiment, by providing the fading cable 230, the directivity of the array antenna can be tilted. The fading cable 230 is connected to the first wideband dipole antenna 212A that receives the radio wave first, out of the two first wideband dipole antennas 212A and the second wideband dipole antenna 212B. By doing so, the directivity can be tilted toward the first wideband dipole antenna 212A to which the fading cable 230 is connected, so that the wavelength shift can be corrected.

<Receiver 250 and control device 260>
As shown in FIG. 3, a receiver 250 is connected to the second coaxial switch 236. The receiver 250 receives the reception signal output from the second coaxial switch 236. In this way, radio waves from Jupiter can be received by the receiver 250. The receiver 250 has frequency characteristics capable of receiving radio waves of 3 to 50 MHz.

  The receiver 250 amplifies the received signal input from the second coaxial switch 236, processes the waveform of the received signal, converts the received signal into a digital signal as received data (amplitude data), The received data can be transmitted to the control device 260.

  The receiver 250 is communicably connected to the control device 260. The control device 260 is, for example, a personal computer. The control device 260 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an HDD (Hard Disk Drive), a communication interface and a display. With the communication interface, the control device 260 can communicate with the receiver 250 and can communicate with the analysis server 300 and the distribution system 400 via the network line 90.

  Control device 260 sends a command to receiver 250 to send the received data. The receiver 250 transmits received data to the control device 260 in response to the command. The control device 260 receives the received data transmitted from the receiver 250 and stores it in the HDD or the like.

  The control device 260 calculates intensity data from the stored received data. For example, intensity data is calculated by squaring received data (amplitude data). The calculated intensity data is displayed on the display. The intensity data displayed on the display is displayed according to each time. By displaying the intensity data on the display, it is possible to visually recognize how the intensity of the received radio wave changes with time.

  The control device 260 outputs a control signal for driving the first coaxial switching devices 232a and 232b. With this control signal, one of the three fading cables 230a, 230b, and 230c can be selected.

  Similarly, the control device 260 outputs a control signal for driving the second coaxial switch 236. One of the first antenna device 210A and the second antenna device 210B can be selected by this control signal.

  As described above, the control device 260 is communicably connected to the analysis server 300 via the network line 90. Analysis server 300 transmits a transmission command for transmitting the received data to control device 260. The control device 260 transmits the received data stored in the HDD or the like to the analysis server 300. In this way, the analysis server 300 can collect received data from the control device 260 of the receiving system 200 installed in various places. The analysis server 300 can analyze the collected reception data and determine whether or not a disturbance has occurred in the F layer of the ionosphere above a specific area.

<< Measurement and transmission processing of F layer of ionosphere >>
FIG. 4 is a flowchart showing measurement and transmission processing of the F layer of the ionosphere. This measurement and transmission processing is executed in the receiver 250 and the control device 260 of the reception system 200 installed at each of the observation points A to N.

  First, the control device 260 determines whether or not to start measurement (step S411). This determination process is a process for determining whether to start receiving radio waves that reach the earth from the planet, in particular, radio waves that reach the earth from Jupiter. The reception of the ionosphere and radio waves may be affected by various kinds of electromagnetic waves from the sun flare and the ground. These effects are less at night than at daytime. For this reason, it is preferable to receive radio waves at night. The determination process of step S411 is a process of determining whether or not a start time preferable for receiving radio waves has been reached.

  Sunset time and sunrise time vary depending on the season and region. Therefore, the start time for receiving radio waves needs to be determined according to the sunset time, the area, and the like. The start time determined in this way can be stored in advance in the HDD of the control device 260 in correspondence with the date and region. The control device 260 can make the determination in step S411 by reading the start time corresponding to the date and area from the HDD. The control device 260 has a calendar function, and the date data is updated as appropriate. In addition, by providing the control device 260 with a GPS (Global Positioning System) function, it is possible to acquire the area where the control device 260 is installed. By doing in this way, the control apparatus 260 can acquire a month day and an area | region automatically, and can determine the start time corresponding to a month day and an area.

  In the above-described example, the case where the control device 260 independently determines whether or not to start measurement is shown. On the other hand, a measurement start command may be transmitted from the analysis server 300 to the control device 260 via the network line 90 to start reception of radio waves. In this case, the determination process of step S411 is a process of determining whether or not a measurement start command is received from the analysis server 300.

  When it is determined in the determination process in step S411 that measurement is started (YES), the frequency to be received is determined (step S413). A plurality of frequencies, for example, eight frequencies that can be simultaneously received by the receiver 250 are determined. What is necessary is just to determine suitably a preferable frequency in order to determine the critical frequency mentioned later as a some frequency. The critical frequency may vary depending on the season, and a plurality of frequencies are determined according to the season and stored in advance in an HDD or the like. The processing in step S413 is processing in which the control device 260 reads data of a plurality of frequencies from the HDD or the like, transmits data of the plurality of frequencies to the receiver 250, and determines the measurement conditions of the receiver 250.

  Next, the receiver 250 performs reception and recording processing (step S415). In this reception and recording process, the receiver 250 receives radio waves of each of the plurality of frequencies from the antenna system 205 according to the data of the plurality of frequencies transmitted from the control device 260. Furthermore, the receiver 250 converts the received signal received into a digital signal as received data, and transmits the received data to the control device 260 at an appropriate timing.

  Next, the control device 260 determines whether or not to end the measurement (step S417). As described above, the sunrise time varies depending on the season and region. Therefore, the end time for receiving the radio wave can also be determined according to the sunset time, the region, or the like, and can be stored in advance in the HDD of the control device 260 or the like. Similarly to the start time, the end time corresponding to the date and region can be determined.

  In the determination process of step S417, when it is determined that the measurement is not finished (NO), the control device 260 returns the process to step S415. In this way, the control device 260 can continuously receive radio waves at night.

  In the determination process in step S417, when the control device 260 determines that the measurement is finished (YES), the process returns to step S411. In this way, the control device 260 can wait until the next measurement is started.

  When it is determined that the measurement is not started in the determination process in step S411 described above (NO), it is determined whether or not to transmit data (step S419). This process is a process of determining whether or not a transmission command for transmitting received data is transmitted from the analysis server 300 to the control device 260 via the network line 90.

  When control device 260 determines in step S419 that data is to be transmitted (YES), that is, when it receives a transmission command, it transmits the received data stored in the HDD of control device 260 to analysis server 300. (Step S421). By doing in this way, the analysis server 300 can collect the reception data which received the radio wave which arrives at the earth from Jupiter at nighttime.

  The analysis server 300 can collect the reception data stored at each of the observation points A to N by transmitting a transmission command to the control device 260 of the reception system 200 at each of the observation points A to N. it can. In this way, reception data in a predetermined area, for example, all over Japan can be collected.

<< F-layer disturbance analysis processing of ionosphere >>
5 and 6 are flowcharts showing the F-layer disturbance analysis process of the ionosphere. The ionospheric F-layer disturbance analysis process is executed in the analysis server 300 and the distribution system 400. This process is mainly performed in the daytime. As described above, the analysis server 300 collects the reception data stored at each of the observation points A to N, and analyzes whether or not a disturbance has occurred in the F layer of the ionosphere using the collected reception data. .

  First, the analysis server 300 selects one frequency at the observation point (step S511). For example, a frequency of 10 MHz at the observation point A among the observation points A to N is selected. By analyzing all the frequencies for all the observation points A to N, it is possible to specify the region where the disturbance has occurred.

  Next, the analysis server 300 reads received data at one time at the selected frequency (step S513). The received data is data indicating the amplitude of the received radio wave, for example.

  Next, the analysis server 300 calculates the intensity from the read received data and determines whether the intensity is less than a predetermined intensity (step S515). For example, the intensity is calculated by calculating the square value of the value of the received data. Also, the predetermined intensity can be zero. In addition, it is preferable to make the value of a noise level into predetermined intensity. By doing in this way, the determination process of step S515 can determine whether or not the intensity of the received radio wave has become zero, or whether or not the intensity of the received radio wave has decreased to a noise level. .

  When the analysis server 300 determines in step S515 that the received radio wave intensity is less than the predetermined intensity (YES), the first time when the received radio wave intensity is less than the predetermined intensity is stored. (Step S517). By storing the time when the intensity is less than the predetermined intensity, it is possible to calculate the duration time during which the intensity is continuously less than the predetermined intensity.

  Next, the analysis server 300 classifies and stores the frequency selected in step S511 as a reflection frequency (step S519).

  If the analysis server 300 determines that the intensity of the received radio wave is equal to or higher than the predetermined intensity in the determination process in step S515 (NO), the frequency selected in step S511 is classified and stored as a transmission frequency (step S521). .

  By the processing in steps S519 and S521 described above, one frequency selected in step S511 can be classified as a reflection frequency or a transmission frequency.

  After executing the process of step S519 or S521, the analysis server 300 determines whether or not the intensity of the received radio wave has returned to a predetermined intensity or higher (step S523).

  When the analysis server 300 determines that the intensity of the received radio wave has returned to the predetermined intensity or higher (YES), the analysis server 300 stores the second time when the radio wave intensity has returned to the predetermined intensity or higher (step S525).

  Next, the analysis server 300 calculates the time when the intensity of the radio wave is less than the predetermined intensity from the difference between the first time stored in the process of step S517 and the second time stored in the process of step S525. Calculate (step S527).

  After executing the process of step S527 or when the analysis server 300 determines that the intensity of the radio wave received in the process of step S523 has not returned to the predetermined intensity or more (NO), the analysis server 300 analyzes all the times when the radio wave is received. It is determined whether or not it has been done (step S529). When the analysis server 300 determines that all the times at which radio waves are received have not been analyzed (NO), the analysis server 300 returns the process to step S513.

  When the analysis server 300 determines that the analysis has been performed for all the times at which the radio waves are received (YES), the analysis server 300 determines whether the analysis has been performed for all the plurality of frequencies (step S531). For example, the analysis server 300 determines whether eight frequencies have been analyzed.

  When the analysis server 300 determines that the eight frequencies are not analyzed (NO), the analysis server 300 returns the process to step S511. When the analysis server 300 determines that eight frequencies have been analyzed (YES), the analysis server 300 determines a critical frequency from the reflection frequency and the transmission frequency classified by the processing of steps S519 and S521 (step S533). For example, an intermediate frequency between the highest reflection frequency among the frequencies classified as the reflection frequency and the lowest transmission frequency among the frequencies classified as the transmission frequency is set as the critical frequency.

  Next, the analysis server 300 calculates the average value m and the standard deviation σ, or the median value M and the quartile deviation Q in the past predetermined period that has already been measured (step S611). For example, the predetermined period in the past can be a period such as the past 15 days from the previous day to 15 days ago.

  Next, the analysis server 300 determines whether or not the critical frequency calculated in the process of step S533 exceeds the index value m + nσ or M + nQ (step S613). Here, n can be a value of 1.5, 2.0, 2.5, 3.0, or the like.

  Next, when the analysis server 300 determines that the critical frequency calculated in the process of step S533 exceeds the index value m + nσ or M + nQ (YES), the analysis server 300 determines the magnitude with reference to the prediction table (step S615). For example, the prediction table is a table that defines the magnitude relationship corresponding to the index value m + nσ or M + nQ and the duration. The duration time is the time calculated in the process of step S527.

  FIG. 7A is a table showing an example of a prediction table. The prediction table shown in FIG. 7A defines the magnitude relationship corresponding to the index value m + nσ and the duration. When the index value is m + 1.5σ or more and less than m + 2.0σ and the duration is 1 hour, the magnitude is determined as Ma. For example, Ma is a value such as magnitude 3. The magnitude can be determined by referring to the prediction table shown in FIG. 7A by using the index value m + nσ or M + nQ and the duration.

  Next, the analysis server 300 determines the scheduled occurrence date when the earthquake occurs (step S617). For example, it is possible to determine the scheduled occurrence date by preliminarily defining an occurrence probability table as shown in FIG. The occurrence probability table shown in FIG. 7B is a table showing the relationship between the period from the detection of disturbance in the F layer to the occurrence of an earthquake, the number of occurrences, and the probability of occurrence of an earthquake. This table is a table in which the number of days from when a disturbance occurred in the F layer in the past to when an earthquake actually occurred is recorded and tabulated. This table shows that the number of earthquakes that occurred 3 days after the disturbance in the F layer was the highest (18 times (56% probability)). These values are updated each time an F-layer disturbance and an actual earthquake occur, so that it is possible to gradually increase the accuracy of prediction of the scheduled occurrence date.

  Next, the analysis server 300 transmits the magnitude and the scheduled date of occurrence to the distribution system 400.

  The distribution system 400 determines a partner who issues an alert (step S619). For the other party who issues the alert, the relationship between the classification and the magnitude of various target persons such as the contract category, the region, and the business type is defined in advance. Specifically, the contract classification can be classified into individuals, companies, and the like. In addition, it is possible to divide contracts into categories such as individual business owners, small and medium enterprises, large enterprises, restaurants, and services. In the present embodiment, these are classified as contract category A and contract category B. For example, when the magnitude value is large, an alert is sent to both the contract category A and the contract category B, and when the magnitude value is small, an alert is sent only to the contract category A. Prepare for earthquakes according to differences in contract categories. Also, it is possible to determine a partner to send an alert according to the region.

  Next, the distribution system 400 issues an alert to the partner determined in step S619 (step S621). For example, an alert mail is sent to the other party.

<< D layer monitoring >>
As described above, the F layer of the ionosphere is farthest from the ground among the ionosphere, and thus is less susceptible to electromagnetic waves from the ground. However, since various electromagnetic waves from the universe go to the earth, there is a possibility of being affected by various celestial bodies. From this point of view, not only the monitoring of the F layer but also the D layer can be monitored to improve the prediction accuracy.

  As described above, radio waves from planets such as Jupiter can be detected to monitor the F layer of the ionosphere. On the other hand, the D layer of the ionosphere can be monitored by receiving a radio wave emitted from the ground and reflected by the D layer.

<< Measurement and transmission processing of D layer of ionosphere >>
FIG. 8 is a flowchart showing measurement and transmission processing of the ionosphere D layer. This measurement and transmission processing can also be executed by the receiver 250 and the control device 260 of the reception system 200 installed at each of the observation points A to N.

  First, the control device 260 determines whether or not to start measurement (step S811). This determination process is the same process as step S411 described above, and is a process for determining whether or not a preferred start time for receiving radio waves has been reached.

  If it is determined in step S411 that measurement is to be started (YES), the frequency at which the VLF / LF radio wave to be received is received is determined (step S813). This is the same processing as step S413 described above.

  Next, the receiver 250 performs reception and recording processing (step S815). This is the same processing as step S413 described above.

  Next, the control device 260 determines whether or not to end the measurement (step S817). This is the same processing as step S417 described above.

  In the determination process of step S417, when it is determined that the measurement is not finished (NO), the control device 260 returns the process to step S815. In this way, the control device 260 can continuously receive radio waves at night.

  In the determination process of step S817, when the control device 260 determines that the measurement is finished (YES), the process returns to step S811. In this way, the control device 260 can wait until the next measurement is started.

  If it is determined in the determination process in step S811 that measurement is not started (NO), it is determined whether data is transmitted (step S819). This process is a process of determining whether or not a transmission command for transmitting received data is transmitted from the analysis server 300 to the control device 260 via the network line 90. This is the same processing as step S419 described above.

  When control device 260 determines in step S819 that data is to be transmitted (YES), that is, when it receives a transmission command, it transmits the received data stored in the HDD of control device 260 to analysis server 300. (Step S821). By doing in this way, the analysis server 300 can collect the reception data received at night in the daytime. This is the same processing as step S421 described above. The collected received data is stored in the HDD of the analysis server 300 or the like.

  The analysis server 300 can collect the reception data stored at each of the observation points A to N by transmitting a transmission command to the control device 260 of the reception system 200 at each of the observation points A to N. it can. In this way, reception data in a predetermined area, for example, all over Japan can be collected.

<< Disturbance analysis processing >>
FIG. 9 is a flowchart showing a process of analyzing the disturbance generated in the D layer and F layer of the ionosphere and the radio waves radiated from the microcracks.

  First, the analysis server 300 calculates the average value m and the standard deviation σ of the VLF / LF radio wave amplitude in the past predetermined period that has already been measured (step S911). For example, the predetermined period in the past can be a period such as the past 15 days from the previous day to 15 days ago.

  Next, the analysis server 300 reads the amplitude A at one time from the HDD (step S913). The analysis server 300 can acquire the amplitude A by reading the reception data stored in the HDD.

  Next, the analysis server 300 determines whether or not the amplitude A read in the process of step S913 is less than the index value mnσ calculated in the process of step S911 (step S915).

  Next, when the analysis server 300 determines in step S915 that the amplitude A is less than the index value m−nσ (YES), whether or not there is an abnormality in the supplementary observation (ULF / GPS satellite observation or the like). Is determined (step S917). Specifically, this supplementary observation is performed by observing the state of the microcrack using radio waves (for example, radio waves of 10 Hz or less) radiated from the microcrack before the earthquake, or by radio waves transmitted from GPS satellites. This is a method of observing the amount of change in electron density in the entire ionosphere using (for example, radio waves of two frequencies such as 1.57542 GHz and 1.2276 GHz).

  The processes in steps S911 to S915 described above are processes for analyzing whether or not a disturbance has occurred in the D layer of the ionosphere. The fact that it has been determined in step S915 that the amplitude A has fallen below the index value means that a disturbance has occurred in the D layer of the ionosphere. On the other hand, when it is determined in step S917 that the supplementary observation (ULF / GPS satellite observation, etc.) is abnormal, it is determined that a microcrack has occurred or that the entire ionosphere has been disturbed. It is.

  Next, when the analysis server 300 determines that the supplementary observation (ULF / GPS satellite observation or the like) is abnormal in the determination process of step S917 (YES), the analysis server 300 indicates the F-layer disturbance analysis process of the ionosphere shown in FIG. Call and execute a subroutine. That is, when it is determined that a disturbance has occurred in the D layer of the ionosphere, it is further determined whether a disturbance has also occurred in the F layer of the ionosphere.

  In this way, it is possible to determine whether or not disturbance has occurred not only in the ionosphere F layer but also in the ionosphere D layer, thereby improving the accuracy of earthquake prediction. Further details will be described below.

<< Monitoring of D layer and F layer >>
The D layer of the ionosphere is 60 km to 90 km from the ground and is closest to the ground. On the other hand, the F layer of the ionosphere is furthest from 150 km to 800 km from the ground. Charge fluctuations due to microcracks, which are the precursors of an earthquake, reach the ionosphere, causing changes in the electron density (plasma density) of the ionosphere and causing disturbance in the ionosphere. When the magnitude of the earthquake is small, the charge fluctuation due to microcracks is also small. On the other hand, when the magnitude of the earthquake is large, the charge fluctuation due to microcracks is also large. Therefore, the magnitude of the magnitude can be determined by the charge fluctuation caused by the microcrack.

  Since charge fluctuations due to microcracks mainly occur in the ground, the charge fluctuations propagate gradually from the ground toward the sky. When the magnitude of the earthquake is extremely small, the charge fluctuation is also very small and the D layer closest to the ground is not reached. Furthermore, when the magnitude of the earthquake is a certain magnitude, the charge fluctuation is also a certain magnitude, and the D layer close to the ground is affected by the charge fluctuation due to the microcrack and is disturbed. In this case, the charge fluctuation does not reach the F layer far from the ground, the disturbance does not occur in the F layer, and the disturbance occurs only in the D layer.

  Furthermore, when the charge fluctuation due to the microcracks is further large, the charge fluctuation reaches the F layer after a predetermined time, for example, about 3 hours after reaching the D layer. Therefore, in this case, not only the D layer but also the F layer is disturbed.

  Thus, when the magnitude of the earthquake is small to some extent, only the D layer is disturbed. When the magnitude of the earthquake is large, disturbance occurs in both the D layer and the F layer. In this case, first, disturbance occurs in the D layer, and then disturbance occurs in the F layer after a predetermined time has elapsed.

  From the above, when disturbance occurs in the D layer, it can be predicted that at least some earthquake will occur. Further, if no disturbance occurs in the F layer after a predetermined time, it can be predicted that an earthquake with a small magnitude will occur. On the other hand, if a disturbance occurs in the F layer after a lapse of a predetermined time after the disturbance occurs in the D layer, it can be predicted that an earthquake having a large magnitude will occur. In addition, when disturbance occurs only in the F layer, it can be determined that the earthquake is not caused by the effect of noise from radio waves from the universe and is not caused by microcracks, thus preventing false alarms. be able to. By monitoring both the D layer and the F layer in this way, the accuracy of magnitude can be increased, and the possibility of erroneously determining the occurrence of an earthquake can be reduced.

  Furthermore, the duration during which radio waves that pass through the F layer cannot be continuously received is the time during which disturbances have continuously occurred in the F layer. When the duration is long, the magnitude tends to increase. Therefore, by comprehensively judging the monitoring of both the D layer and the F layer and the measurement of the duration during which the disturbance has occurred, the accuracy of the magnitude of the earthquake that occurs can be further increased.

  Furthermore, it is also possible to classify the target person who sends the alert. For example, those who issue an alert when disturbance occurs even in D layer alone, those who issue an alert when disturbance occurs in both D layer and F layer, and alert when the duration exceeds a predetermined time It can be classified as a person who emits.

200 Receiving System 205 Antenna System 210A, 210B Antenna Device 250 Receiver 260 Control Device 300 Analysis Server 400 Distribution System

Claims (5)

First analysis means for performing a first analysis and determining whether a disturbance of the first layer in the ionosphere has occurred;
Second analysis means for performing a second analysis and determining whether or not a disturbance has occurred in the second layer higher than the first layer;
An earthquake occurrence prediction means for predicting the occurrence of an earthquake based on the determination result by the first analysis means and the determination result by the second analysis means,
The earthquake occurrence prediction means predicts that an earthquake will occur if it is determined by the first analysis means that a disturbance has occurred in the first layer ,
When it is determined by the first analysis means that a disturbance has occurred in the first layer, and when the second analysis means determines that a disturbance has occurred in the second layer, the first analysis means causes the first analysis to occur. Predicting that an earthquake with a greater magnitude will occur than when it was determined that there was a disturbance in the layer and the second analysis means did not determine that a disturbance had occurred in the second layer,
Predicting that an earthquake will not occur if the first analysis means does not determine that a disturbance has occurred in the first layer and the second analysis means determines that a disturbance has occurred in the second layer. Earthquake prediction system characterized by   The first analyzing means determines whether or not the amplitude of the VLF / LF radio wave is below a predetermined index value, and determines that the disturbance has occurred in the first layer when it is determined that the amplitude is below the predetermined index value. The earthquake prediction system according to claim 1.   3. The earthquake prediction system according to claim 1, wherein the second analysis unit determines that a disturbance has occurred in the second layer based on an amount of change in electron density calculated from GPS radio waves. Said second analyzing means, if the critical frequency determined on the basis of the radio wave emitted from extraterrestrial celestial bodies to determine Taka not exceed a predetermined index value, is determined to have exceeded, said second layer The earthquake prediction system according to claim 1, wherein it is determined that a disturbance has occurred. The earthquake occurrence predicting means is configured such that, when the time when the disturbance is generated in the second layer is the first time, the time when the disturbance is generated in the second layer is shorter than the first time. than when a second time, earthquake prediction system according to any one of claims 1 to 4, characterized in that predicting the large magnitude earthquake occurs.