JP2019086480A - Earthquake warning system - Google Patents

Abstract

To provide an earthquake warning system capable of predicting, with high degree of accuracy, a maximum acceleration of a main vibration (S-wave) using a maximum acceleration of a preliminary tremor (P-wave).SOLUTION: The earthquake warning system calculates a maximum acceleration of the S-wave of an earthquake that has occurred by multiplying a maximum acceleration of the P-wave by a coefficient α, and performs a process to cope with the earthquake in accordance with the calculated maximum acceleration of the S-wave, the coefficient α is calculated using the following formulas (1), (2).SELECTED DRAWING: Figure 2

Description

  The present invention relates to an earthquake warning system that predicts the maximum acceleration of a main vibration (S wave) from the maximum acceleration of an initial fine movement (P wave) and executes processing such as an alarm.

  If it is possible to predict the magnitude of the maximum acceleration of the main vibration (S wave) of the earthquake based on the maximum acceleration of the initial tremor (P wave) of the generated earthquake, for example, the movable It is possible to escape from the great damage by stopping the plant inside before the arrival of the main vibration (S wave).

As such an attempt, for example, in the cited reference 1 (Japanese Unexamined Patent Publication No. 2017-122623), using observation data of initial tremors of earthquakes observed at a single observation point In the method of estimating the maximum amplitude, the maximum amplitude of the main movement is determined by the derivation step of deriving the maximum amplitude of the initial fine movement from the observation data, and the linear expression of the maximum amplitude of the initial fine movement derived in the derivation step. And estimating the maximum amplitude of the main movement, wherein the coefficient of the maximum amplitude of the initial tremor in the linear equation is the logarithm of the dominant vibration frequency in the ground around the observation point. A method of estimating the maximum amplitude of the main motion of an earthquake, which has been calculated and set by a function, is disclosed.
JP 2017-122623 A

  In the prior art described in the cited document 1, it is assumed that the maximum amplitude of the initial movement can be derived and the maximum amplitude of the main movement can be determined from the linear expression of the maximum amplitude of the derived initial movement. The coefficient a (amplitude ratio between the maximum amplitude y of the main movement and the maximum amplitude x of the initial tremor) of the next term is calculated by the logarithmic function of the dominant vibration frequency of the ground around the observation point.

  However, there is a problem that the coefficient a thus obtained is low in accuracy, and the maximum acceleration of the main vibration (S wave) can not be predicted with high accuracy from the maximum acceleration of the initial fine movement (P wave). The

  If the prediction accuracy of the maximum acceleration of the main vibration (S wave) is low, for example, even with the maximum acceleration that would not normally stop, the production line such as a semiconductor factory will be stopped based on the prediction. Things can happen. Once the production line is shut down, it generally takes time and cost to restart the operation, and based on the prediction by the low precision coefficient, the economic loss will be great.

  This invention solves the said subject, The earthquake warning system which concerns on this invention calculates and calculates the maximum acceleration of S wave by multiplying the coefficient (alpha) by the maximum acceleration of P wave of the earthquake which generate | occur | produced In the earthquake warning system that executes processing for responding to the earthquake according to the maximum acceleration of the S wave, the coefficient α is calculated based on the following equation (1) and the following equation (2).

However,
γ _rad : Contribution of radiation effect to the coefficient γ that determines the coefficient α γ _diss : Contribution of attenuation effect to the coefficient γ that determines the coefficient α γ _sit : Contribution of site effect to the coefficient γ that determines the coefficient α γ _trs The contribution of the lateral damping effect to the factor γ which determines the factor α.

  In the earthquake warning system according to the present invention, the contribution to the radiation effect coefficient γ, the contribution to the attenuation effect coefficient γ, and the contribution to the site effect coefficient γ based on the equations (1) and (2) According to the earthquake warning system according to the present invention, the factor α is calculated from the factor γ obtained from these factors, taking into consideration the contribution to the factor γ of the lateral attenuation effect in a minute. The maximum acceleration of the main vibration (S wave) can be predicted with high accuracy from the maximum acceleration of the initial fine movement (P wave).

It is a figure which shows the example of installation of the earthquake warning system 1 which concerns on embodiment of this invention. It is a figure showing an outline of earthquake warning system 1 concerning an embodiment of the present invention. It is a figure explaining the concept of alpha coefficient. It is a figure which shows the data structure of the alpha coefficient table used with the earthquake warning system 1 which concerns on this invention. It is a figure showing a flow chart of processing of earthquake warning system 1 concerning an embodiment of the present invention. It is a figure which shows the image of the data measured by the 1st seismograph 101, the 2nd seismograph 102, and the 3rd seismograph 103. FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a view showing an installation example of a main system 100 of an earthquake warning system 1 according to an embodiment of the present invention.

  In the earthquake warning system 1 according to the embodiment of the present invention, at least three seismographs are provided in a building or a site in a business site, and detection and determination of P waves based on measurement data from these three seismographs And so on. In the present embodiment, as shown in FIG. 1, an example in which three seismographs including a first seismograph 101, a second seismograph 102, and a third seismograph 103 are installed is shown.

  However, seismographs need to be installed in the site (including the inside of the building) to which the building belongs with a certain distance apart. If the seismographs are placed close to each other, for example, the vibration of a truck traveling on a nearby road will be measured, and a plurality of seismographs will measure together, which interferes with P wave detection. .

  Here, although the appropriate distance between seismographs is a case-by-case according to a building and a site where the seismographs are installed, for example, about 30 m to 100 m are assumed. Hereinafter, as an example, in the present embodiment, the earthquake warning system 1 will be described based on a case where the building and site around Tokyo Station are installed.

  In the earthquake warning system 1 according to the present embodiment, three or more seismographs are used to make the system fail safe, but at least one seismograph is used if certain conditions are satisfied. The invention can also be realized.

  FIG. 2 is a view showing an outline of the earthquake warning system 1 according to the embodiment of the present invention.

  In the earthquake warning system 1 according to the present invention, as described above, seismographs (first seismograph 101, second seismograph 102, and third earthquake seismograph 101 installed at an appropriate distance apart at one point. A total of 103).

First seismometer 101, second seismometer 102, data measured by the third seismometer 103 (measurement data signals of each seismometer called S _1, S _2, S _3), the data processing unit 110 Will be sent. The data processing unit 110 in the main system 100 is a general-purpose information processing apparatus including a CPU, a ROM that holds programs operating on the CPU, and a RAM that is a work area of the CPU. Data measured by the first seismograph 101, the second seismograph 102, and the third seismograph 103 can be analyzed by the data processing unit 110.

  The data processing unit 110 cooperates with and operates each component connected to the data processing unit 110 shown. Further, various control processes in the earthquake warning system 1 according to the present invention are realized by the CPU executing a program stored and held in storage means such as ROM and RAM in the data processing unit 110.

  In the data processing unit 110, a non-volatile, rewritable storage unit 120 is connected so as to be capable of data communication, and in the storage unit 120, a data table (α coefficient table) and the like described later are particularly stored. The data processing unit 110 can refer to the table.

  The notification unit 130 is, for example, a means for visually transmitting an earthquake warning such as a display device, and a means such as a speaker for transmitting an earthquake warning by hearing. The notification unit 130 is activated by being controlled by the trigger from the data processing unit 110 to execute an earthquake warning.

  In this embodiment, the notification unit 130 activated by the trigger to transmit an earthquake warning to a person is used. For example, when the earthquake warning system 1 according to the present invention is used in a factory or the like, this is used. In addition to the notification unit 130 as described above, it is also possible to add an automatic stop device that automatically stops the production line based on a trigger from the data processing unit 110.

  Further, the communication unit 150 transmits data transferred from the data processing unit 110 to the external network N or receives data transmitted from the external network N, and the received data is transmitted to the data processing unit 110. It can be sent to and from.

  Such a communication unit 150 is configured to be able to receive an emergency earthquake bulletin transmitted from the Japan Meteorological Agency and to obtain data relating to the epicenter of the generated earthquake. In the present invention, as long as data relating to the epicenter can be acquired, it is possible to use information sources other than the earthquake early warning.

  Here, the α coefficient in the α coefficient table stored in the storage unit 120 will be described.

  When an earthquake occurs, shaking from the hypocenter propagates on the ground as seismic waves. There are initial tremor (P wave) and main vibration (S wave) in seismic waves, and P wave propagates faster than S wave. The P wave travels fast and energy is small, whereas the S wave slows down and generates a high energy roll.

  The earthquake that has occurred is mainly due to the S wave that is transmitted after that causes damage due to strong shaking. For this reason, it becomes possible to perform alerting etc. before S wave is transmitted at the stage which detected P wave transmitted previously, using the difference in speed to which seismic waves are transmitted. For example, it is possible to escape large damage by stopping a moving factory before the arrival of the main vibration (S wave).

  Based on such a concept, the coefficient α is used to predict the magnitude of the S-wave to be propagated later based on the magnitude of the P-wave propagated earlier. More specifically, the coefficient α is a coefficient that makes it possible to calculate and predict the maximum acceleration of the S wave by multiplying the maximum acceleration of the P wave of the generated earthquake by the coefficient α.

  The value of this coefficient α changes depending on the place where the earthquake warning system 1 is installed and the area to which the epicenter belongs. Therefore, according to the place where the earthquake warning system 1 is installed, the α coefficient needs to be calculated in advance and stored in a table or the like. FIG. 3 is a diagram for explaining the concept of the α coefficient. Moreover, FIG. 4 is a figure which shows the data structure of the alpha coefficient table used with the earthquake warning system 1 which concerns on this invention.

  Assuming that the earthquake warning system 1 is in the vicinity of Tokyo Station, for example, an area of an epicenter can be set as Tachikawa, Tama, and northern Tokyo Bay. Here, each of these will be referred to as area 1, area 2 and area 3. In addition, about such an area, it is also possible to utilize what was subdivided. In addition, other areas such as area 1, area 2 and area 3 can be set for such an area.

Now, for the area around Tokyo Station where the earthquake warning system 1 is installed, α ₁ used in calculating the maximum acceleration of the S wave of the earthquake having the area 1 as the epicenter in advance and the S wave of the earthquake having the area 2 as the epicenter The α ₂ used when calculating the maximum acceleration of the following, and α ₃ used when calculating the maximum acceleration of the S wave of the earthquake whose area is the area ₃ are prepared, and these are used as an α coefficient table as shown in FIG. It is stored in the storage unit 120.

Taking the alpha ₁ for use in the maximum acceleration of the S-wave seismic for the area 1 and epicenter calculation example, the calculation of the alpha _1, past earthquakes s ₁₁ generated in area 1, s _12, s ₁₃ , S ₁₄ , s ₁₅ , s ₁₆ ,... Earthquake data is used.

  Next, the processing and operation of the earthquake warning system 1 according to the present invention configured as described above will be described. FIG. 5 is a diagram showing a flowchart of processing of the earthquake warning system 1 according to the embodiment of the present invention.

  In FIG. 5, when the process is started in step S100, it is then determined in step S101 whether a P wave is detected. FIG. 6 is a view showing an image of data measured by the first seismograph 101, the second seismograph 102, and the third seismograph 103. As shown in FIG.

As a determination method of P wave detection, for example, measurement data signals of the first seismograph 101, the second seismograph 102, and the third seismograph 103 are any _two measurement data of S ₁ , S ₂ , and S _3. Although whether or not a predetermined threshold value has been exceeded can be used, it is not limited to such a method as long as an accurate determination can be made.

  When the determination result in step S101 is NO, step S101 is looped. On the other hand, when the P wave is detected and the determination result in step S101 is YES, the process proceeds to step S102.

  Then, in step S102, data of the Meteorological Agency's earthquake early warning is acquired via the network N, and data on the area of the epicenter is acquired from the earthquake early warning.

  Next, in step S103, an α coefficient corresponding to the area acquired in step S102 is acquired from the α coefficient table.

In step S104, A _s = α × A _p is calculated based on the α coefficient acquired in step S103. Here, A _p is the largest of the acceleration of the P-wave, which is measured (maximum acceleration), A _s is the maximum acceleration of the S wave is calculated and prediction based on this.

In addition, in the flowchart according to the present embodiment shown in FIG. 5, information that can be acquired by so-called earthquake early warning is not taken into consideration, but using information that can be acquired by emergency earthquake bulletin when the can is be a predicted value a _s is calculated and predicted in S104, the comprehensive judgment from the predicted value by the earthquake early warning, the prediction value based on the comprehensive judgment, executes the determination process of S105 after Is preferred.

In step S105, it is determined whether A _s > A _t based on the calculated A _s . Here, A _t is the maximum acceleration of the S wave as the threshold value.

  If the determination in step S105 is YES, the process proceeds to step S106, and the alarm unit 130 notifies an earthquake warning, or stops the production line in the case where the automatic stop device as described above is added. And take appropriate action and processing in accordance with the predicted earthquake.

  In step S107, the process ends.

  By the way, there is a problem that the conventional α coefficient has low estimation accuracy, and the maximum acceleration of the main vibration (S wave) can not be predicted with high accuracy from the maximum acceleration of the initial fine movement (P wave).

  Then, if the prediction accuracy of the maximum acceleration of the main vibration (S wave) is low, for example, even at the maximum acceleration which would otherwise be unnecessary to stop, a production line such as a semiconductor factory will be stopped based on the prediction. Such a situation may occur. Once the production line is shut down, it generally takes time and cost to restart, and based on predictions with low precision coefficients, economic losses will be significant. There was a problem that.

  Therefore, in the earthquake warning system 1 according to the present invention, the prediction accuracy of the maximum acceleration of the main vibration (S wave) is improved by using the α coefficient calculated by the following method.

  Here, the coefficient γ defined by the following equation (1) is defined.

  The coefficient γ is assumed to be the sum of each term as shown on the left side of the following equation (2).

here,
γ _rad : Contribution of radiation effect to the coefficient γ that determines the coefficient α γ _diss : Contribution of attenuation effect to the coefficient γ that determines the coefficient α γ _sit : Contribution of site effect to the coefficient γ that determines the coefficient α γ _trs The contribution of the lateral damping effect to the factor γ which determines the factor α.

The calculation of each term will be described below. First, the contribution γ _rad to the coefficient γ of the radiation effect of the earthquake will be described. For the radiation effect component of the alpha coefficient of the earthquake warning system 1 according to the present invention, see Aki and Richards, 2002 (K. Aki & PG Richards 1980. Quantitative Seismology, Theory and Methods. Volume I: 557 pp., 169 illustrations. Volume II: Calculate using the theoretical formula of 373 pp., 116 illustrations. San Francisco: Freeman.). Here, the entire content of the article is incorporated herein by reference.

According to this paper, the coefficient γ _rad based on fault movement due to the double coupled hypocenter can be expressed as the following equation (3) by polar coordinates (r, θ, φ) in the fault plane coordinate system.

Here, A _po and A _so are the amplitudes of the P wave and the S wave on the epicenter sphere, respectively. Also, V _p and V _s are seismic wave propagation velocities of P wave and S wave respectively.

Next, the contribution _γdis to the coefficient γ of the damping effect of the earthquake will be described. The contribution _γdis due to the damping effect is the respective dominant frequencies f _p and f _s of the P wave and the S wave, and the attenuation coefficients Q _p and Q _s of the P wave and the S wave, respectively The seismic wave propagation velocity V _p , V _s is used to calculate as the following equation (4).

  (4) For derivation of the equation, Kawase and Matsuo, 2004 (H. Kawase and H. Matsuo (2004), K-NET, KiK-net, and JMA earthquake source, path and site characteristics using strong motion waveform Segregation analysis of the Japan Earthquake Engineering Society, Vol. 4, No. 1, 33-50. Here, the entire contents of these articles are incorporated herein by reference.

Next, the contribution γ _sit to the coefficient γ of the site effect of the earthquake will be described. Regarding the site effect component of the α coefficient of the earthquake warning system 1 according to the present invention, it is seen in Kamogawa, 1992 (Saburo Sugakawa, Masashi Matsuoka, Koichi Sakugawa (1992): Maximum acceleration and maximum velocity of the 1987 Chiba Prefecture Tohooki earthquake) Evaluation of ground characteristics, Proceedings of the Architectural Institute of Japan, No. 442, pp. 71-78), Fujimoto and Kamogawa, 2006 (Kazuo Fujimoto, Saburo Kamogawa (2006) Proceedings of the Japan Society for Earthquake Engineering, Vol. 6, The theoretical formulas of No. 1 and 11-22, relationship between ground amplification factor based on strong motion records of pairs of close observation stations and average S-wave velocity of ground, 2) are used. Here, the entire contents of these articles are incorporated herein by reference.

The contribution γ _dis due to the site effect is calculated using the ground amplification factors β _p and β _s of the P wave and the S wave, respectively, as shown in the following equation (5).

Next, the contribution γ _trs to the coefficient γ of the lateral attenuation effect of the earthquake will be described. In calculating the α coefficient of the earthquake warning system 1 according to the present invention, such a lateral attenuation effect is newly introduced to further improve the accuracy.

When calculating the α coefficient, combining the radiation effect, the attenuation effect, and the site effect and comparing them with the observed values, it can be seen that
The component of the radiation effect is the basic factor of α, which is the experience coefficient.
The theoretical value of the radiation effect diverges from the fact that the P wave becomes zero on the tangent surface, but the observed value does not show so large value. It is inferred that the fault model is not an ideal double-coupled hypocenter, that there are phenomena in wave propagation such as reflection and refraction, and so on.
• By averaging the estimated values around the exit direction, highly correlated results with observed values can be obtained, but a large residual remains.

Based on the above findings, in addition to the attenuation coefficient Q representing the attenuation in the direction of the longitudinal azimuth, the lateral direction (newly) (in the calculation of the α coefficient of the earthquake alarm system 1 according to the present invention). It is solved by the introduction of the attenuation coefficient Q _t of transversal).

The contribution by this lateral attenuation effect γ _trs is calculated using the dominant frequency f _s of S wave, the seismic wave propagation velocity V _{s of} S wave, and the newly introduced attenuation coefficient Q _t as shown in the following equation (6) calculate.

However, it can be assumed that the transversal damping coefficient Q _t is correlated with the S-wave damping coefficient Q _s

Defined as Here, n is a real number.

In the earthquake warning system 1 according to the present invention, the α coefficient is calculated using the equations (1) to (7) as described above. In Equations (1) to (7), the unknowns are P wave and S wave seismic wave propagation velocity V _p and V _s , and P wave and S wave predominant frequencies f _p and f _s and P wave respectively. The attenuation coefficients Q _p and Q _{s of} the waves and S waves, and ground amplification factors β _p and β _{s of} the P waves and S waves, respectively, and n in the equation (7).

In the calculation of the α coefficient in the earthquake warning system 1 according to the present invention, for example, experience in past earthquakes s ₁₁ , s ₁₂ , s ₁₃ , s ₁₄ , s ₁₅ , s ₁₆ ,. Parameter fitting is performed using, for example, the least squares method so that all values of the coefficients α ₁₁ , α ₁₂ , α ₁₃ , α ₁₄ , α ₁₅ , α ₁₆ . Define the unknown number. This makes it possible to calculate the α coefficient with higher accuracy.

1 ... earthquake warning system 101 ... first seismograph 102 ... second seismograph 103 ... third seismograph 110 ... data processing unit 120 ... storage unit 130 ... notification unit 150 ··· Communication unit N ··· Network

Claims (1)

An earthquake warning system that calculates the maximum acceleration of the S wave by multiplying the maximum acceleration of the generated P wave of the earthquake by the coefficient α, and executes processing for coping with the earthquake according to the calculated maximum acceleration of the S wave. In
An earthquake warning system characterized by calculating a coefficient α based on the following equation (1) and the following equation (2).

However,
γ _rad : Contribution of radiation effect to the coefficient γ that determines the coefficient α γ _diss : Contribution of attenuation effect to the coefficient γ that determines the coefficient α γ _sit : Contribution of site effect to the coefficient γ that determines the coefficient α γ _trs The contribution of the lateral damping effect to the factor γ which determines the factor α.

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