JP2018091637A - Liquid seismograph - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid seismograph suitable for predicting occurrence of a natural disaster.SOLUTION: The liquid seismograph 100 comprises a liquid-filled balloon 12, a difference synthesizer 16 which detects a signal as a function of deformation of the balloon 12, a surface acoustic wave convolver 20 for obtaining the correlation between a difference synthesis signal and a reference signal corresponding to a deformation mode of the balloon 12 deformed on previous occurrence of an earthquake, and a tsunami occurrence prediction unit 22 for predicting a tsunami occurrence based on a correlation signal from the surface acoustic wave convolver 20.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a liquid seismometer, and more particularly, to a liquid seismometer suitable for predicting the occurrence of a natural disaster.

  Conventionally, as a seismometer using a liquid, for example, a seismometer described in Patent Document 1 is known.

  The seismometer described in Patent Document 1 receives light reflected from the liquid level contained in a container by a light receiving means and converts it into an electrical signal, and determines whether an earthquake shake has occurred from the output of the light receiving means. To do.

JP 2009-216493 A

  However, since the seismometer described in Patent Document 1 detects whether or not light is received by the light receiving means because the liquid level is disturbed by the vibration of the earthquake, it only detects the occurrence of the earthquake. It is not possible to predict until the occurrence of

  Therefore, the present invention has been made paying attention to such an unsolved problem of the conventional technology, and aims to provide a liquid seismometer suitable for predicting the occurrence of natural disasters. .

  The present inventors paid attention to the pulling wave as a precursor to the Great East Japan Earthquake and the tsunami caused by it. Why do pulling waves occur? One of the factors is the attraction (hereinafter referred to as “tsunami attraction”) caused by the mass of the tsunami that is approaching and the crustal deformation, and this attraction attracts seawater in the bay and the coast. It is believed that there is. The tsunami's attractive force should have also acted on the seawater collected at the bottom of the fishing boat. In addition, it has been reported that gravity changes occur due to crustal movements caused by earthquakes. It is also possible that gravity changes will occur due to crustal movements before the earthquake occurs. Accordingly, the present inventors have focused on the fact that a balloon filled with a liquid is deformed by a tsunami attractive force or the like, and have arrived at the present invention for predicting a disaster (earthquake or tsunami) by taking this phenomenon.

  [Invention 1] In order to achieve the above object, a liquid seismometer of Invention 1 includes a balloon filled with liquid, a signal detection means for detecting a signal corresponding to deformation of the balloon, and a signal from the signal detection means. A correlator that correlates with a reference signal corresponding to a deformation mode of the balloon that has been deformed when an earthquake occurred in the past, and a natural disaster occurrence prediction unit that predicts the occurrence of a natural disaster based on the correlation signal from the correlator. Prepare.

  With such a configuration, when the balloon is deformed due to a tsunami attractive force or the like when an earthquake occurs, a signal corresponding to the deformation of the balloon is detected by the signal detection means and input to one input of the correlator. The other input of the correlator is supplied with a reference signal corresponding to the deformation mode of the balloon that has been deformed when a past earthquake occurred. For this reason, the correlator correlates the signal from the signal detection means with the reference signal corresponding to the deformation mode of the balloon deformed when the past earthquake occurred. Then, the occurrence of natural disaster is predicted by the natural disaster occurrence prediction means based on the correlation signal from the correlator.

  The deformation of the balloon is caused not only by the tsunami attraction, but also by vibrations such as seismic waves and noise, temperature, humidity and other environmental conditions, aging of the balloon and other various factors. For this reason, it is difficult to accurately predict the occurrence of a natural disaster even if only the deformation of the balloon is detected. Therefore, the present invention generates a reference signal based on the deformation mode of the balloon that has been deformed at the time of the occurrence of a past earthquake, and correlates the signal corresponding to the deformation of the balloon with the reference signal by a correlator. It predicts the occurrence of natural disasters.

  [Invention 2] The liquid seismometer according to Invention 2 is the liquid seismometer according to Invention 1, further comprising imaging means for taking an image of the surface of the balloon, wherein the signal detection means is obtained at a predetermined time difference from the imaging means. The difference signal of the obtained image signal is output.

  If it is such a structure, the image of the surface of a balloon will be image | photographed by an imaging | photography means, and the difference signal of the image signal obtained by predetermined time difference from the imaging | photography means will be output by a signal detection means.

  [Invention 3] The liquid seismometer according to Invention 3 is the liquid seismometer according to Invention 2, further comprising a plurality of imaging means for imaging images of different surfaces of the balloon, and the signal detection means is provided for each imaging means. Then, a difference signal of the image signal obtained by the predetermined time difference is generated from the photographing means, and a signal obtained by synthesizing the generated difference signals is output.

  With such a configuration, images of different surfaces of the balloon are photographed by a plurality of photographing means, and a signal detection means generates a differential signal of image signals obtained with a predetermined time difference from the photographing means for each photographing means. Then, a signal obtained by synthesizing the generated difference signals is output.

  [Invention 4] The liquid seismometer according to Invention 4 is the liquid seismometer according to any one of Inventions 2 and 3, wherein the linear pattern extending in a direction perpendicular to the direction in which the balloon is deformed when an earthquake occurs is described above. Attached to the surface of the balloon.

  In such a configuration, since the surface of the balloon is provided with a linear pattern extending in a direction orthogonal to the direction in which the balloon is deformed when an earthquake occurs, the image content changes when the balloon is deformed. Becomes larger.

  [Invention 5] The liquid seismometer according to Invention 5 is the liquid seismometer according to any one of Inventions 1 to 4, further comprising filtering means for filtering a signal input from the signal detection means to the correlator. The means passes the signal component in the frequency band in which the balloon is deformed in accordance with the gravity change at the time of the earthquake occurrence, and removes the signal component in the higher frequency band.

  With such a configuration, the signal component in the frequency band in which the balloon is deformed according to the gravity change at the time of the occurrence of the earthquake passes through the filtering means, and the signal component in the higher frequency band is removed.

  The present invention detects a change in gravity. The change in gravity has the following characteristics.

(1) Since the change is extremely weak as compared with fluctuation due to seismic waves or aging deterioration, the S / N ratio of the signal from the signal detection means is extremely small.

(2) Since the change of gravity at the time of earthquake occurrence is gradual, the fluctuation cycle (frequency) is lower than that of seismic waves.

(3) Although the change in gravity at the time of the earthquake is moderate, the fluctuation cycle (frequency) is higher than the fluctuation due to temperature, humidity, aging, etc.

  The present invention focuses on the above characteristic (2), and increases the S / N ratio by removing a signal component having a frequency higher than the change in gravity at the time of occurrence of the earthquake by the filtering means.

  [Invention 6] Further, the liquid seismometer of Invention 6 is the liquid seismometer of Invention 5, wherein the filtering means is a signal in a frequency band lower than a frequency band in which the balloon is deformed in accordance with a gravity change at the time of occurrence of the earthquake. Remove ingredients.

  With such a configuration, the filtering means removes signal components in a frequency band lower than the frequency band in which the balloon is deformed in accordance with the gravity change at the time of the occurrence of the earthquake.

  The present invention pays attention to the characteristic (3) above, and enhances the S / N ratio by removing signal components having a frequency lower than the change in gravity at the time of the occurrence of the earthquake by the filtering means.

  As described above, according to the liquid seismometer of aspect 1, the occurrence of a natural disaster is predicted from the correlation between the signal corresponding to the deformation of the balloon and the reference signal corresponding to the deformation mode of the balloon deformed at the time of the past earthquake occurrence. Therefore, it is possible to predict the occurrence of natural disasters more accurately than in the past.

  Furthermore, according to the liquid seismometer of the invention 2, since it is only necessary to take an image of the surface of the balloon with an imaging means and output a difference signal, a signal corresponding to the deformation of the balloon is detected with a relatively simple configuration. be able to.

  Furthermore, according to the liquid seismometer of aspect 3, since a difference signal is generated for each imaging means and a signal obtained by synthesizing these is output, a signal corresponding to the deformation of the balloon can be detected with high accuracy.

  Furthermore, according to the liquid seismometer of the invention 4, since the change of the image content becomes large when the balloon is deformed, the deformation of the balloon can be detected with high sensitivity.

  Furthermore, according to the liquid seismometer of the invention 5, noise having a high frequency such as a seismic wave can be removed, so that the S / N ratio of the signal from the signal detecting means can be improved.

  Furthermore, according to the liquid seismometer of the invention 6, noise having a low frequency such as fluctuation due to aging or the like can be removed, so that the S / N ratio of the signal from the signal detecting means can be further improved. .

1 is a perspective view of a liquid seismometer 100. FIG. 1 is a plan view of a liquid seismometer 100. FIG. 2 is a functional block diagram of a liquid seismometer 100. FIG.

  Embodiments of the present invention will be described below. 1 to 3 are diagrams showing this embodiment.

First, the configuration of the present embodiment will be described.
FIG. 1 is a perspective view of a liquid seismometer 100. FIG. 2 is a plan view of the liquid seismometer 100.

  As shown in FIGS. 1 and 2, the liquid seismometer 100 includes a quadrangular prism-shaped hollow housing 10, a balloon 12 suspended from the ceiling of the housing 10, and 4 mounted in the housing 10. And a single CCD camera 14.

  The balloon 12 is made of a silicon rubber balloon or the like. The balloon 12 is filled with a liquid such as water. The surface of the balloon 12 is provided with a linear pattern (not shown) extending in a direction orthogonal to the direction in which the balloon 12 is deformed when an earthquake occurs. It is preferable that the shape, dimensions, material and other specifications of the balloon 12, the liquid filling rate, and the pattern mode are set to optimum values so that the deformation of the balloon 12 can be detected with high sensitivity by the CCD camera 14.

  Each of the CCD cameras 14 is disposed on the same horizontal plane and is disposed at an interval of 90 degrees from the center of the balloon 12. The four CCD cameras 14 can take images of the surface of the balloon 12 at intervals of 90 degrees.

FIG. 3 is a functional block diagram of the liquid seismometer 100.
As shown in FIG. 3, the liquid seismometer 100 includes a difference synthesizer 16 that processes an image signal from the CCD camera 14 and a band that filters a signal from the difference synthesizer 16 (hereinafter referred to as “difference synthesized signal”). The pass filter 18, the surface acoustic wave convolver 20 that correlates the signal from the band pass filter 18 and the reference signal, and the tsunami generation prediction unit 22 that predicts the occurrence of a tsunami based on the correlation signal from the surface acoustic wave convolver 20. And is configured.

  The difference synthesizer 16 generates a difference signal of image signals obtained from the CCD camera 14 with a predetermined time difference for each CCD camera 14, and outputs a signal obtained by synthesizing the generated difference signals. As the difference signal, for example, an image signal from the CCD camera 14 is held in a buffer for a predetermined time, an image signal currently obtained from the CCD camera 14, and an image signal obtained from the CCD camera 14 a predetermined time ago. It is generated by calculating the difference of.

  The bandpass filter 18 allows a signal component in a frequency band in which the balloon 12 is deformed according to a change in gravity when an earthquake occurs to remove a signal component in a frequency band other than this. The frequency band of the bandpass filter 18 may be set so that, for example, a signal obtained from the differential synthesizer 16 when a past earthquake has occurred is recorded, and the correlation signal from the surface acoustic wave convolver 20 is maximized. it can.

  The other input of the surface acoustic wave convolver 20 is input with a reference signal corresponding to the deformation mode of the balloon 12 deformed when a past earthquake occurred. For example, a signal obtained from the difference synthesizer 16 when a past earthquake has occurred can be recorded and used as a reference signal.

  When the level of the correlation signal from the surface acoustic wave convolver 20 exceeds a predetermined level, the tsunami occurrence prediction unit 22 outputs a notification that warns of the occurrence of a tsunami. This notification may be output as sound, or may be transmitted to other terminals via a network such as the Internet.

Next, the operation of the present embodiment will be described.
When the balloon 12 is deformed due to the tsunami attraction in the event of an earthquake, the differential synthesizer 16 detects a signal corresponding to the deformation of the balloon 12 and removes signal components in the low frequency band and the high frequency band via the bandpass filter 18. And input to one input of the surface acoustic wave convolver 20. The other input of the surface acoustic wave convolver 20 receives a reference signal corresponding to the deformation mode of the balloon 12 that has been deformed when a past earthquake occurred. For this reason, the surface acoustic wave convolver 20 correlates the signal from the bandpass filter 18 with the reference signal corresponding to the deformation mode of the balloon 12 that has been deformed when a past earthquake occurred. Then, the tsunami occurrence prediction unit 22 outputs a notification warning the occurrence of the tsunami based on the correlation signal from the surface acoustic wave convolver 20.

Next, the effect of this embodiment will be described.
In the present embodiment, the liquid seismometer 100 includes a balloon 12 filled with liquid, a difference synthesizer 16 that detects a signal corresponding to the deformation of the balloon 12, a difference synthesized signal, and a balloon that has been deformed when an earthquake occurred in the past. A surface acoustic wave convolver 20 that correlates with a reference signal corresponding to the twelve deformation modes; and a tsunami generation prediction unit 22 that predicts the generation of a tsunami based on the correlation signal from the surface acoustic wave convolver 20.

  As a result, the occurrence of the tsunami is predicted from the correlation between the signal corresponding to the deformation of the balloon 12 and the reference signal corresponding to the deformation mode of the balloon 12 deformed at the time of the past earthquake occurrence. Occurrence can be accurately predicted.

  Further, in the present embodiment, the difference synthesizer 16 generates a difference signal of the image signal obtained with a predetermined time difference from the CCD camera 14 for each CCD camera 14, and outputs a signal obtained by combining the generated difference signals. To do.

  As a result, the CCD camera 14 only needs to capture an image of the surface of the balloon 12 and generate a difference signal, so that a signal corresponding to the deformation of the balloon 12 can be detected with a relatively simple configuration. Further, since a differential signal is generated for each CCD camera 14 and a signal obtained by synthesizing these signals is output, a signal corresponding to the deformation of the balloon 12 can be detected with high accuracy.

  Further, in the present embodiment, a linear pattern extending in a direction orthogonal to the direction in which the balloon 12 is deformed when an earthquake occurs is applied to the surface of the balloon 12.

  Thereby, since the change of the image content becomes large when the balloon 12 is deformed, the deformation of the balloon 12 can be detected with high sensitivity.

  Further, in the present embodiment, the liquid seismometer 100 includes a bandpass filter 18 that filters a signal input from the differential synthesizer 16 to the surface acoustic wave convolver 20, and the bandpass filter 18 includes a change in gravity when an earthquake occurs. Accordingly, the signal component in the frequency band in which the balloon 12 is deformed is passed, and the signal component in the other frequency band is removed.

  Thereby, noise having a high frequency such as seismic waves and noise having a low frequency such as fluctuation due to aging deterioration can be removed, so that the S / N ratio of the differential composite signal can be improved.

  In the present embodiment, the CCD camera 14 corresponds to the imaging means of the invention 2 or 3, the difference synthesizer 16 corresponds to the signal detection means of the invention 1 to 3 or 5, and the bandpass filter 18 corresponds to the invention 5. The surface acoustic wave convolver 20 corresponds to the correlator according to the first or fifth aspect. Further, the tsunami occurrence prediction unit 22 corresponds to the natural disaster occurrence prediction means of the first aspect.

[Modification]
In the above embodiment, four CCD cameras 14 are provided. However, the number is not limited to this, and the number of CCD cameras 14 is arbitrary. When the number of the CCD cameras 14 is one, the difference synthesizer 16 may be replaced with a differencer that outputs a difference signal of the image signal obtained from the CCD camera 14 with a predetermined time difference.

  Further, in the above embodiment and its modifications, the plurality of CCD cameras 14 are arranged on the same horizontal plane, but may be arranged directly above and below the balloon 12. When the CCD camera 14 is arranged directly above the balloon 12, the liquid filling rate is adjusted to about 80% so that the liquid level is formed in the balloon 12, and an image of the liquid level is taken by the CCD camera 14. Thereby, when the balloon 12 is deformed, the change in the liquid surface shape becomes large, so that the deformation of the balloon 12 can be detected with high sensitivity.

  Further, in the above-described embodiment and the modification thereof, the bound pass filter 18 is provided, but not limited thereto, the signal component in the frequency band in which the balloon 12 is deformed according to the gravity change at the time of the occurrence of the earthquake, A low-pass filter that removes signal components in a higher frequency band may be provided. In addition, a high-pass filter may be provided that allows a signal component in a frequency band in which the balloon 12 is deformed according to a gravity change at the time of an earthquake to pass, and removes a signal component in a frequency band lower than this.

  Moreover, in the said embodiment and its modification, it was set as the structure which uses one reference signal, However, Not only this but a some reference signal can also be used. In this case, the surface acoustic wave convolver 20 may be provided by the number of reference signals, or the reference signals may be switched to time series and input to the surface acoustic wave convolver 20.

  Moreover, in the said embodiment and its modification, it was set as the structure which uses the one liquid seismometer 100, However, Not only this but many liquid seismometers 100 are installed in various areas, The liquid seismometer 100 Can be employed to improve the S / N ratio of the differential composite signal. Specifically, for example, the following configuration can be employed.

  A temperature sensor or the like is attached to the liquid seismometer 100, and sensor information obtained from the sensor is transmitted to the server. In addition, the difference composite signal is also transmitted to the server.

  Based on the received sensor information, the server registers noise factor information related to temperature, humidity, and other environmental conditions in the database in association with identification information (ID) of the liquid seismometer 100. The noise factor information includes the date of manufacture of the balloon 12, the date of start of use, and other specifications. The server specifies two liquid seismometers A and B having the same noise factor information by searching. At this time, the noise for each factor such as temperature, humidity, and aging is N1 to Nn, the signal corresponding to the gravity change of the balloon 12 in the liquid seismometer A is S1 (t), and the gravity change of the balloon 12 in the liquid seismometer A is S2 (t) is a signal corresponding to the difference between the liquid seismometer A difference composite signal x1 (t) and the liquid seismometer B difference composite signal x2 (t) is expressed by the following equations (1) and (2). Can do. The difference signal can be expressed by the following equation (3).

x1 (t) = N1 + N2 + ... + Nn + S1 (t) (1)
x2 (t) = N1 + N2 ++ ... + Nn + S2 (t) (2)
x1 (t) -x2 (t) = S1 (t) -S2 (t) (3)
If the noise components are the same, the difference signal of the above equation (3) ideally does not include a noise component. Further, S1 (t) and S2 (t) are almost zero during normal operation. Therefore, the server generates a difference signal of the above equation (3) for the identified liquid seismometers A and B based on the received difference composite signal, and the difference signal and the first reference signal (of the liquid seismometer A The reference signal corresponding to the deformation mode of the balloon 12 deformed at the time of occurrence of the past earthquake in the installation area) is input to the surface acoustic wave convolver 20. Thereby, generation | occurrence | production of a tsunami can be accurately estimated about the installation area of the liquid seismometer A. Similarly, the server inputs the differential signal and the second reference signal (the reference signal corresponding to the deformation mode of the balloon 12 deformed at the time of occurrence of the past earthquake in the area where the liquid seismometer B is installed) to the surface acoustic wave convolver 20. To do. Thereby, generation | occurrence | production of a tsunami can be accurately estimated about the installation area of the liquid seismometer B. FIG.

  If the liquid seismometers A and B are installed at a sufficiently large distance, there is no possibility of being affected by the earthquake at the same time, or the level of interference (S1 (t), S2 (t)) At the same time) can be reduced. Therefore, in specifying the liquid seismometers A and B, it is preferable to specify in consideration of the installation distance. That is, position information indicating the installation position of the liquid seismometer 100 is registered in the database in association with the identification information (ID) of the liquid seismometer 100, and the two noise sensors have the same noise factor information and the largest installation distance. Liquid seismometers A and B are specified by searching.

  In the above-described embodiment and its modification, the CCD camera 14 is provided, and a signal corresponding to the deformation of the balloon 12 is detected based on the image signal from the CCD camera 14. A distance measuring sensor for measuring the distance to the surface may be provided, and a signal corresponding to the deformation of the balloon 12 may be detected based on the distance measuring signal from the distance measuring sensor. In addition, as a method for detecting a signal corresponding to the deformation of the balloon 12, any method can be adopted.

  In the above embodiment and its modification, the length of the reference signal has not been described. However, when the reference signal becomes long, the reference signal is compressed on the time axis and input to the surface acoustic wave convolver 20. On the other hand, a modulator that compresses the signal from the bandpass filter 18 on the time axis and inputs the compressed signal to the surface acoustic wave convolver 20 can be provided.

  Moreover, in the said embodiment and its modification, although it aimed at the liquid seismometer which is a system which detects the signal according to the deformation | transformation of the balloon 12, it is not limited to this but targets other types of seismometers. The sensor signal obtained therefrom can be input to the surface acoustic wave convolver 20 to predict the occurrence of an earthquake, tsunami or other natural disaster. That is, the configuration subsequent to the difference synthesizer 16 can be applied to other types of seismometers.

  Moreover, in the said embodiment and its modification, although the surface acoustic wave convolver 20 was employ | adopted, not only this but another kind of correlator can also be employ | adopted.

  In the above embodiment and its modifications, the present invention is applied to the case of predicting the occurrence of a tsunami. However, the present invention is not limited to this, and can be applied to other cases without departing from the gist of the present invention. is there. For example, when a gravity change occurs due to crustal movement or the like before an earthquake occurs, the occurrence of the earthquake can also be predicted. In addition, since it has been reported that gravity changes occur due to crustal deformations caused by earthquakes, not only the prediction scene, but also when notifying the occurrence of earthquakes, tsunamis and other natural disasters, and at the time of earthquakes, tsunamis and other natural disasters It can also be applied to observing what kind of gravity change has occurred.

DESCRIPTION OF SYMBOLS 100 ... Liquid seismometer, 10 ... Housing, 12 ... Balloon, 14 ... CCD camera, 16 ... Differential synthesizer, 18 ... Band pass filter, 20 ... Surface acoustic wave convolver, 22 ... Tsunami generation prediction part

Claims (6)

A balloon filled with liquid;
Signal detection means for detecting a signal corresponding to the deformation of the balloon;
A correlator that correlates a signal from the signal detection means with a reference signal corresponding to a deformation mode of the balloon that has been deformed when a past earthquake occurred;
A liquid seismometer, comprising: natural disaster occurrence prediction means for predicting the occurrence of a natural disaster based on a correlation signal from the correlator. In claim 1,
A photographing means for photographing an image of the surface of the balloon;
The liquid seismometer, wherein the signal detection means outputs a difference signal of image signals obtained with a predetermined time difference from the imaging means. In claim 2,
A plurality of the photographing means for photographing images of different surfaces of the balloon;
The signal detection means generates a difference signal of the image signals obtained by the predetermined time difference from the imaging means for each imaging means, and outputs a signal obtained by synthesizing the generated difference signals. Total. In any one of Claim 2 and 3,
A liquid seismometer, wherein a linear pattern extending in a direction orthogonal to a direction in which the balloon is deformed when an earthquake occurs is attached to the surface of the balloon. In any one of Claims 1 thru | or 4,
Filtering means for filtering a signal input from the signal detection means to the correlator;
The liquid seismometer, wherein the filtering means passes a signal component in a frequency band in which the balloon is deformed in accordance with a gravity change at the time of an earthquake, and removes a signal component in a higher frequency band. In claim 5,
The liquid seismometer, wherein the filtering means removes a signal component in a frequency band lower than a frequency band in which the balloon is deformed according to a gravity change at the time of occurrence of an earthquake.

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