JP2008076321A - Earthquake prediction method and earthquake prediction device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an earthquake prediction method and an earthquake prediction device that observe an electric field for indicating premonitory symptoms of an earthquake, discriminates the electric field for indicating the premonitory symptoms from an electric field, such as artificial noise and atmospherics, and detects the electric field for indicating the premonitory symptoms for predicting an earthquake. <P>SOLUTION: It has been observed that electric field pulses occurs over a wide frequency band in a seismic center region due to flow potential following diastrophism for indicating the premonitory symptoms of an earthquake in the seismic center region, charge separation, or the like following minute cracks before a large earthquake. They are distinguished according to the difference in the spectrum of the electric fields and that of occurrence time, thus predicting a large earthquake. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an earthquake prediction method and an earthquake prediction apparatus for detecting a precursory phenomenon of an earthquake based on electric field observation and predicting a large earthquake.

  It has been well known for more than 50 years that radio noise is observed in the vicinity of the epicenter before a major earthquake. Earthquake prediction was widely performed by observing the electric field (hereinafter, including ground current, surface charge, etc.) of a precursor to an earthquake.

For example, the disaster prevention system and device using the emergency earthquake bulletin described in Japanese Patent Application No. 2006-184190 proposed by the present applicant is set by the epicenter information received by the epicenter information receiving unit and the position information setting unit Based on the location information, the predicted earthquake intensity and main arrival time are calculated. The tomography method for the area of occurrence of longwaves and ground currents of earthquake precursors described in Japanese Patent Publication No. 5-36000 is the simultaneous observation and reception of longwaves and ground currents of earthquake precursors in at least four locations in the ground or on the sea floor.・ From the interrelationship between the detected signals, the point of occurrence of the long wave / geoelectric current fluctuation and the intensity distribution are calculated three-dimensionally to obtain a stereoscopic image and temporal change.
Japanese Patent Application No. 2006-184190 Japanese Patent Publication No. 5-36000

  However, the conventional methods of observing the electric field noise and the electric field of earthquake precursors are difficult to discriminate between the electric field of earthquake precursors and the electric field of natural noise such as artificial noise and static electricity, and the reliability of earthquake prediction due to these is lacking. There was a drawback. The earthquake prediction based on the observation of the electric field is not practically used, and the discrimination between the earthquake precursor electric field and the artificial noise / natural noise is an urgent issue to be solved.

(First invention)
The earthquake prediction method according to the first aspect of the invention predicts an earthquake by observing an electric field at three or four or more observation points separated from each other by 50 to 300 km where no strong noise is observed. In the frequency band including 13 kHz, an electric field pulse other than a lightning strike is simultaneously observed at the observation point to obtain the spectrum of the electric field pulse, and the spectrum of the electric field pulse, the spectral characteristics of the known lightning, and the ionospheric propagation attenuation of the lightning. And comparing the characteristics, removing the electric field pulses caused by lightning from the known lightning spectrum, extracting only the electric field pulses different from the reception spectra of the adjacent lightning and long-distance lightning, and further, At the observation point, artificial noise is removed from the electric field pulse not including the lightning electric field, and the pulse within the propagation time difference between the observation points is removed. The source region is calculated from the time difference between two or more pairs between the pulses observed within the difference in propagation time between the observation points, and within the propagation time difference between the source region and the observation points. The earthquake is predicted by analyzing the pulse observed in (1).

(Second invention)
The earthquake prediction apparatus according to the second aspect of the invention predicts an earthquake by observing an electric field at three or four or more observation points separated from each other by 50 km to 300 km where no strong noise is observed. A spectrum extraction storage means for observing an electric field pulse other than a lightning strike at the observation point and obtaining a spectrum of the electric field pulse, a spectrum obtained by the spectrum extraction storage means, and a known lightning spectrum. Spectrum comparison means for comparing characteristics and lightning ionospheric propagation attenuation characteristics, and electric field pulse extraction that removes electric field pulses caused by lightning by the spectrum comparison means and extracts only electric field pulses that are different from the reception spectrum of near lightning and long-distance lightning Means, and further, the electric field pulse not including a lightning electric field at the observation point In addition, a timer means for giving a time signal, and a noise removing means for extracting only a pulse within a propagation time difference between the observation points from the electric field pulse to which the time signal is given, and removing artificial noise, An epicenter region calculating means for calculating an epicenter region from two or more sets of time differences between the electric field pulses observed within the propagation time difference between the observation points, and an epicenter region calculated by the epicenter source calculating unit; And an electric field pulse analyzing means for analyzing the electric field pulse observed within a difference in propagation time between the observation points, wherein the electric field pulse analyzing means makes a prediction immediately before a large earthquake. To do.

  According to the present invention, since artificial noise and natural noise can be removed, it is possible to easily observe an electric field pulse representing an earthquake precursor. In addition, according to the present invention, it is possible to easily observe the electric field pulse indicating the precursor of the earthquake, so that a large earthquake can be predicted.

The principle of the present invention will be described. Before a major earthquake, it has been observed that electric field pulses are generated over a wide frequency band in the source region due to the flow potential accompanying the crustal movement of the earthquake precursor in the source region and charge separation associated with microcracks. . Further, it is known that most of the natural noise is a pulse burst whose electric field intensity is inversely proportional to the frequency, and the precursor electric field pulse usually satisfies the following relationship.
E (12 kHz) <E (3 kHz) <E (1.5 kHz) (1)
Here, E (fkHz) indicates a received electric field strength having a frequency of fkHz.

  Natural noise has the largest lightning electric field. The frequency of the lightning field strength maximum is usually in the range of 3 kHz to 10 kHz (wavelength 30 km to 100 km). From the frequency characteristics of the lightning electric field, the electric field of the adjacent lightning does not satisfy the right side of the equation (1). On the other hand, when the electric field intensity of lightning is 100 Hz to 1 MHz, attenuation due to ionospheric propagation (about 1000 km or more) is large from 1 kHz to 3 kHz. Due to this frequency characteristic and attenuation characteristic, the intensity of the deep lightning is maximized around 12 kHz. The electric field of the far lightning does not satisfy the left side of equation (1). In other words, the electric field that satisfies Equation (1) is not from lightning.

  In the 1kHz to 13kHz band where there is little continuous strong noise, according to observations over 10 years so far, temporary noise other than lightning is also pulsed, but it is not so strong, at a point about 50km to 300km away. , Not observed at the same time (shorter than the propagation time between observation points). When a temporary pulse is observed at a time difference of 1 ms or more at two points about 50 km to 300 km apart, the difference in distance between the source and the two points is 300 km or more, and the source of the pulse observed at the two points Will not be the same earthquake precursor pulse.

  Based on the above, the pulses observed at three or more locations at the same time (with a shorter time than the propagation time between observation points) satisfying the formula (1) are separated from each other by about 50 km to 300 km and have no continuous strong noise. In this case, it is assumed that the wave source is not a noise source but a precursor electric field generated before an earthquake.

(First invention)
The earthquake prediction method according to the first aspect of the present invention enables prediction immediately before a large earthquake by detecting and discriminating an earthquake precursor electric field pulse. In the earthquake prediction method, electric field pulses are observed at three or four or more observation points separated from each other by 50 to 300 km where no strong noise is observed. The observation point is a frequency band including 1 kHz to 13 kHz, and an electric field pulse other than that during lightning strike is simultaneously observed to obtain a spectrum of the electric field pulse. The spectrum of the electric field pulse is then compared with the known lightning spectral characteristics and lightning ionospheric propagation attenuation characteristics.

  The electric field pulse different from the reception spectrum of the near lightning and the long distance lightning is extracted by removing the electric field pulse caused by the lightning from the known lightning spectrum. Further, at the three or four or more observation points, artificial noise is removed from the electric field pulse not including the electric field of lightning, and only pulses within the propagation time difference between the observation points are extracted. The hypocenter region is calculated from the time difference between two or more sets of the pulses observed within the propagation time difference between the observation points.

(Second invention)
The earthquake prediction apparatus according to the second aspect of the invention predicts immediately before a large earthquake by observing an electric field at three or four or more observation points separated from each other by 50 to 300 km where no strong noise is observed. Spectral extraction storage means, at the observation points separated by the distance, in a frequency band including 1 kHz to 13 kHz, for example, 1 kHz to 2 kHz, 2.5 kHz to 3.5 kHz, 10.5 kHz to 13 kHz, at the observation point, An electric field pulse other than that during a lightning strike is observed to obtain a spectrum of the electric field pulse, and the spectrum is extracted and stored.

  The spectrum comparison means compares the spectrum obtained by the spectrum extraction storage means with the known lightning spectrum characteristics and lightning ionospheric propagation attenuation characteristics previously stored in the known spectrum extraction storage means. The electric field pulse extracting means removes the electric field pulse caused by the lightning by the spectrum comparing means, and extracts only the electric field pulse different from the reception spectrum of the near lightning and the long distance lightning. The timer means gives a time signal to the electric field pulse not including the electric field of lightning at the observation point. The noise removing means removes the artificial noise by extracting only the pulses within the propagation time difference between the observation points from the electric field pulse to which the time signal is given.

  The epicenter calculation means calculates a hypocenter region from the time difference of two or more sets between the electric field pulses observed within the propagation time difference between the observation points. The electric field pulse analyzing means analyzes the electric field pulse observed within the propagation time difference between the epicenter area calculated by the epicenter calculation means and the observation point. The epicenter region analyzed by the electric field pulse analyzing means is displayed on the display as necessary. Since the natural noise such as lightning is removed, the earthquake prediction device of the present invention can observe an electric field pulse caused by a current or a surface charge generated before the earthquake, so that an electric field immediately before a large earthquake can be accurately observed. Can do.

  FIG. 1 is a schematic block diagram for explaining a method for immediately predicting a large earthquake by discrimination / detection of an earthquake precursor electric field pulse according to an embodiment of the present invention. In FIG. 1, System 1 is an example of an electric field observation system installed at an observation point. Since System 2 to System i are configured from the same block configuration diagram as that of System 1, only the configuration of System 1 will be described. The System 1 receives an electric field with an electric field observation antenna 11, amplifies the output with an amplifier 12, converts the output into a digital signal with an A / D converter 13, a low-pass filter 14, a mid-pass filter 15, The high frequency filter 16 separates the output into three types of frequency bands, and inputs each output to the first computer 17.

  The first computer 17 obtains a spectrum of a received electric field from the three types of frequency bands, compares it with a spectrum of noise such as a known lightning, and uses only a field pulse that does not match the spectrum of a known noise as a GPS antenna. The time signal obtained from 18 is added, sent to the modem 110 through the public line via the modem 19, and input to the second computer 113. The second computer 113 receives electric field pulses transmitted from three or more observation points of System 1, System 2,... System i through the modems 111 and 112.

  The second computer 113 records only the electric field pulses transmitted from each System that are received simultaneously (within the propagation time difference between observation points) in the storage means. The second computer 113 draws two or more hyperbolas with the observation point as a focal point and a locus with a constant reception time difference by drawing means (not shown), the intersection point as a wave source, and the display 114 along with the date and time. To display.

  The hypocenter area is the generation area of the wave source drawn on the second computer 113, and the scale is the width of the generation area of the wave source, and the second computer 113 is in accordance with an empirical rule from the accumulated time and intensity of the precursor electric field. Is calculated by The date and time of occurrence of an earthquake tends to be longer in proportion to the magnitude of the earthquake within about 10 days from the start of the occurrence of the precursor electric field.

  FIG. 2 is a block diagram for explaining the first computer. In FIG. 2, the first computer 17 includes a spectrum extraction storage unit 21, a spectrum comparison unit 22, a known spectrum storage unit 23, and an electric field pulse extraction unit 25. The first computer 17 obtains the received electric field spectrums f1, f2, and f3 from the three types of frequency bands, and stores them in the spectrum extraction storage means 21. The known spectrum F1 is similarly stored in the known spectrum storage means 23. The spectrum comparison unit 22 compares the spectrum of the received electric field stored in the spectrum extraction storage unit 21 with a known spectrum of noise such as lightning. The electric field pulse extracting means 25 adds only the electric field pulse that does not match the known noise spectrum to the second computer 113 with the time signal obtained from the timer means (GPS antenna) 24 added thereto.

  FIG. 3 is a block diagram for explaining the second computer. In FIG. 3, the second computer 113 includes noise removal means 31, storage means 32, epicenter calculation means 33, and electric field pulse analysis means 34. The second computer 113 removes noise from the electric field pulse transmitted from three or more observation points of System 1, System 2,. The second computer 113 records in the storage means 32 only the electric field pulses transmitted from each System that are received simultaneously (within the propagation time difference between observation points). The epicenter calculation means 33 in the second computer 113 calculates the epicenter from the distance between observation points, the propagation time, and the like.

  The electric field pulse analyzing means 34 analyzes the electric field pulse, draws two or more hyperbolas with the observation point as the focal point and the locus of the constant reception time difference by the drawing means (not shown), and sets the intersection point. A wave source is displayed on the display 114 together with the date and time.

  4, the upper part is a conventional observation example, the middle part is an observation example in which lightning noise is removed from the upper spectrum, and the lower part is a diagram for explaining an observation example in which artificial noise is removed from the middle spectrum. is there. FIG. 4 is an example of observation at the time of the Kii Peninsula offing earthquake on September 5, 2004. The upper part of FIG. 4 shows an electric field pulse including lightning and artificial noise in a conventional observation example. The middle part of FIG. 4 is a diagram in which the lightning electric field pulse is erased from the electric field pulse of the upper part by the method and apparatus of the present invention. The number of electric field pulses is reduced to about 1%. The lower part of FIG. 4 shows only the electric field pulse in which the artificial noise is further eliminated from the middle part by the earthquake prediction method and the earthquake prediction apparatus of the present invention. In the lower part of FIG. 4, many electric field pulses remain about one day before the earthquake, and the earthquake precursor electric field is discriminated and detected. In addition to the earthquake described above, a similar precursor was observed during the Niigata Chuetsu earthquake on October 23, 2004.

It is a schematic block diagram for demonstrating the prediction method immediately before a big earthquake by discrimination / detection of the earthquake precursor electric field pulse which concerns on one Example of this invention. It is a block block diagram for demonstrating a 1st computer. It is a block block diagram for demonstrating a 2nd computer. The upper part is a conventional observation example, the middle part is an observation example in which lightning noise is removed from the upper spectrum, and the lower part is a diagram for explaining an observation example in which artificial noise is removed from the middle spectrum.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Antenna for electric field observation 12 ... Amplifier 13 ... A / D converter 14 ... Low-pass filter 15 ... Middle-pass filter 16 ... High-pass filter 17 ... First computer 18: GPS antenna 19, 110, 111, 112 ... Modem 113 ... Second computer 114 ... Display 21 ... Spectral extraction storage means 22 ... Spectral comparison means 23. ..Known spectrum storage means 24 ... Timer means (GPS antenna)
25 ... Electric field pulse extraction means 31 ... Noise removal means 32 ... Storage means 33 ... Epicenter calculation means 34 ... Electric field pulse analysis means

Claims (2)

An earthquake prediction method for predicting an earthquake by observing an electric field at three or four or more observation points separated from each other by 50 to 300 km where no strong noise is observed,
In the frequency band including 1 kHz to 13 kHz, an electric field pulse other than that during lightning strike is simultaneously observed at the observation point, and a spectrum of the electric field pulse is obtained.
Compare the spectrum of the electric field pulse with the known lightning spectral characteristics and lightning ionospheric propagation attenuation characteristics,
Removing the electric field pulses caused by lightning from the known lightning spectrum, and extracting only electric field pulses different from the reception spectra of the adjacent lightning and long-distance lightning,
Furthermore, at the three or four or more observation points, the artificial noise is removed from the electric field pulse not including the electric field of lightning, and only the pulses within the propagation time difference between the observation points are extracted.
From the time difference between two or more pairs between the pulses observed within the propagation time difference between the observation points, calculate the epicenter area,
An earthquake prediction method, wherein an earthquake is predicted by analyzing the pulse observed within a difference in propagation time between the source region and the observation point. An earthquake prediction apparatus for predicting an earthquake by observing an electric field at three or four or more observation points separated from each other by 50 to 300 km where no strong noise is observed,
Spectrum extraction storage means for observing an electric field pulse other than a lightning strike at the observation point in a frequency band including 1 kHz to 13 kHz and obtaining a spectrum of the electric field pulse;
Spectrum comparison means for comparing the spectrum obtained by the spectrum extraction storage means with the known lightning spectral characteristics and lightning ionospheric propagation attenuation characteristics;
Electric field pulse extraction means for removing electric field pulses due to lightning by the spectrum comparison means, and extracting only electric field pulses different from the reception spectrum of the near lightning and long distance lightning,
Furthermore, timer means for giving a time signal to the electric field pulse not including the electric field of lightning at the observation point;
From the electric field pulse provided with the time signal, only a pulse within the propagation time difference between the observation points is extracted, and noise removing means for removing artificial noise,
An epicenter location calculating means for calculating an epicenter region from a time difference of two sets or three sets or more between the electric field pulses observed within a propagation time difference between the observation points;
An electric field pulse analyzing means for analyzing the electric field pulse observed within the difference in propagation time between the observation points and the epicenter area calculated by the epicenter calculation means;
An earthquake prediction apparatus characterized in that the electric field pulse analysis means predicts immediately before a large earthquake.

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