JP2014215208A - Method and system for predicting intensity of principal motion of earthquake - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and system for predicting intensity of principal motion of an earthquake, capable of predicting the intensity of S-waves at high accuracy even in a case of an earthquake having various P-wave arrival forms by changing prediction expressions according to time course of the P-waves.SOLUTION: The prediction method of the intensity of principal seismic motion includes: preliminarily, calculating a relational expression of a maximum value of observation waveforms of P-waves and a maximum value of observation waveforms of S-waves till an elapsed time on a lapse ratio (an elapsed time from a P-wave arrival detection time to a prediction time/a duration time of P-waves) of a plurality of P-waves at respective earthquake measurement sites in a plurality of pieces of earthquake data occurring in the past; after an on-site seismometer detects an arrival of P-waves, predicting duration of the P-waves and then continuously measuring the P-waves; and predicting the intensity of S-waves to be arrived from the maximum value of the observation waveforms of the observed P-waves sequentially observed till reaching the lapse ratio in the plurality of lapse ratios of the P-waves and the relational expression.

Description

  The present invention relates to a prediction method and a prediction system for estimating the strength of main motion from information on initial microtremors observed by a local seismometer when an earthquake occurs.

  As is well known, as shown in FIG. 9, seismic motion can be roughly classified into initial fine motion (hereinafter abbreviated as P wave) and main motion (hereinafter abbreviated as S wave). And most of the damage caused by earthquakes is caused by earthquake motion caused by S waves.

  On the other hand, since the propagation speed of the S wave is slower than that of the P wave, the arrival of the P wave is first observed when an earthquake occurs, and the S wave arrives after a certain period of time has elapsed. Therefore, in a production facility such as a factory that is required to recover its production capacity early after an earthquake occurs, the magnitude of the intensity of the S wave that arrives later is determined from the P wave information when the earthquake occurs. However, it is desirable that the necessity determination of the emergency stop of the device has already been completed when the S wave arrives.

  Thus, for example, in Patent Document 1 below, a method for predicting the maximum speed value of S waves using the maximum acceleration value of P waves is proposed, and in Patent Document 2 below, information on P waves is used. An alarm system for estimating the intensity of the S wave has been proposed.

JP 2010-164325 A JP 2009-32141 A Shozo Matsumura, Yoshimitsu Okada, Sadayoshi Hori: Processing of earthquake data (high-speed sampling data) in the earthquake precursor analysis system, National Disaster Prevention Science and Technology Center Research Report, No. 41, pp. 44-64, 1988

  However, since these conventional technologies perform prediction based on waveform information of a P wave for a predetermined number of seconds after the occurrence of an earthquake, an earthquake of a P wave, particularly an earthquake with an epicenter far away. For earthquakes in which the waveform grows over several tens of seconds, prediction will be made when the intensity of the P wave does not become sufficiently large, and as a result, the intensity of the S wave that will eventually arrive is determined. There was a tendency to underestimate.

  The present invention has been made in view of the above circumstances, and by changing the prediction formula according to the passage of time of the P wave, the S wave of the S wave can be obtained with high accuracy even for earthquakes of various P wave arrival forms. It is an object of the present invention to provide a prediction method and a prediction system for the main dynamic strength (maximum acceleration and maximum velocity) of an earthquake that can predict the strength (maximum acceleration and maximum velocity).

  In order to solve the above-mentioned problem, the invention according to claim 1 is for predicting the intensity of the S wave reaching the site from the observed waveform of the P wave of the earthquake measured at the site to be predicted. A method for predicting the main dynamic strength of an earthquake, which is based on the data of a plurality of earthquakes that have occurred in the past, and the elapsed rate of a plurality of P waves at each of the earthquake measurement points ( (Elapsed time to prediction time / P wave duration) A relational expression between the maximum value of the observed waveform of the P wave and the maximum value of the observed waveform of the S wave up to the elapsed time of the elapsed rate is obtained, and After the local seismometer detects the arrival of the P wave, it predicts the duration of the P wave, then continuously measures the P wave, and sequentially increases the rate of progress of the P wave. The maximum value of the observed waveform of the P wave observed up to It is characterized in that to predict the strength of the S wave et reach.

  According to a second aspect of the present invention, there is provided a system for predicting the intensity of main motion of an earthquake, which is measured by means of waveform information detecting means for seismic motion installed in the field to be predicted and the waveform information detecting means. Prediction means for predicting the intensity of the S wave that arrives from the observed waveform of the P wave, the prediction means from a plurality of earthquake data that occurred in the past, a plurality of at the measurement point of each of the earthquakes The maximum value of the observed waveform of the P wave up to the elapsed time of the elapsed rate calculated for the elapsed rate of the P wave (elapsed time from the time when the P wave arrival was detected until each prediction time / the duration of the P wave) and the S wave Based on the database storing relational expressions with the maximum value of the observed waveform and the observed waveform sent from the waveform information detecting means, the arrival of the P wave is detected to predict the duration of the P wave, and the waveform information Sent continuously from the detection means From the observed waveform of the P wave, at a plurality of elapsed rates of the P wave, the maximum value of the observed waveform of the P wave that is sequentially observed up to the elapsed rate and the relational expression stored in the database are reached. And a waveform processing unit for predicting the strength of the S wave.

  Further, the invention according to claim 3 is the invention according to claim 2, wherein the waveform processing unit sets a threshold value for the intensity of the S wave in advance and is predicted at the plurality of elapsed rates. When the intensity of the signal exceeds the threshold value, a transmission line for outputting a signal to that effect is provided.

  In the present invention, the initial fine movement is abbreviated as a P wave and the main movement is abbreviated as an S wave. Therefore, the P wave duration is the S wave arrival time from the P wave arrival detection time. Time until.

  In the method for predicting the main dynamic strength of the earthquake according to claim 1 and the prediction system for the main dynamic strength of the earthquake according to claim 2 or 3, each of the data from a plurality of earthquakes that occurred in the past in advance For the elapsed rates of a plurality of P waves at the earthquake measurement point, for example, 0.2, 0.4,... The relational expression with the maximum value of the observed waveform is obtained in advance. And at the time of earthquake occurrence, after the local waveform information detection means to be predicted first detects the arrival of the P wave, the duration of the P wave is predicted, and then the P wave is continuously measured, In the plurality of elapsed rates of the P wave, the intensity of the S wave that arrives from the maximum value of the observed waveform of the P wave that has been observed up to the elapsed rate and the relational expression are predicted.

  In this way, by changing the prediction formula according to the passage of time of the P wave, the earthquake waveform of the P wave takes several tens of seconds, such as earthquakes with various P wave arrival forms, for example, earthquakes with far epicenters. Therefore, it is possible to predict the strength of S waves with high accuracy even for earthquakes that grow.

It is a schematic block diagram which shows one Embodiment of the prediction system of the strength of S wave which concerns on this invention. It is a flowchart which shows the process in the waveform process part of FIG. (A) is a graph which shows the acceleration waveform observed with the seismometer, (b) is a graph which shows the value of STA / LTA calculated from the said acceleration waveform. FIG. 2 is a diagram for explaining a method for predicting the arrival time of an S wave in the waveform processing unit of FIG. 1, wherein (a) is a graph showing an acceleration waveform observed by a seismometer, and (b) is a STA calculated from the acceleration waveform. The graph which estimates the arrival time of S wave from the maximum value of / LTA value, (c) is a graph which shows the state which updated the arrival time prediction of S wave from the maximum value of the newly detected STA / LTA value. . 1A and 1B are diagrams for explaining a method of predicting the intensity of S waves in the waveform processing unit of FIG. 1, in which FIG. 1A is a graph showing predicted S wave arrival times, and FIG. The graph which shows the state which calculates | requires the maximum value of the observation waveform of P wave until the elapsed time of a rate, (c) is a graph which shows the state which estimates the maximum value of S wave from the said maximum value. It is a chart which shows the past earthquake used as the origin of the data stored in the database of FIG. It is a graph which shows the relational expression used for prediction of the duration of the P wave obtained from the past earthquake data of FIG. Calculated from the maximum value of the observed waveform of the P wave and the maximum value of the observed waveform of the S wave up to the elapsed time of each elapsed rate in the elapsed rates of the plurality of P waves obtained from the past earthquake data in FIG. It is a graph which shows the relational expression made. It is a graph which shows the change of the general ground motion which reaches the field.

Hereinafter, based on FIGS. 1-8, one Embodiment of the prediction method and prediction system of the main dynamic strength (maximum acceleration and maximum speed) of the earthquake which concern on this invention is described.
FIG. 1 shows a schematic configuration of the above prediction system. This prediction system includes a seismic motion waveform information detection unit (waveform information detection means) 1 installed on a site to be predicted, and the waveform information detection unit. 1. A personal computer (prediction means, hereinafter abbreviated as PC) 2 for predicting the intensity (maximum acceleration or maximum speed) of the S wave that arrives later from the observed waveform of the P wave measured by 1, and the S wave from this PC And a transmission line 3 that transmits a control signal to related devices and the like when the maximum value of exceeds a threshold value.

Here, in the present embodiment, one or a plurality of seismometers are used as the waveform information detection unit 1, and the time history waveform observed by the seismometer is transmitted to the waveform processing unit 4 of the PC 2. It has become.
The PC 2 has the above-described waveform when a storage device such as a hard disk and an input device such as a keyboard and a mouse, which record an execution program, are connected to a CPU (main control unit) that performs overall control. The processing unit 4 is configured, and the waveform processing unit 4 is connected with a monitor for displaying input / output data and a storage device (output unit) 5 for recording prediction results, a storage device for storing the database 6, and a transmission line 3. It has been done.

  In the database 6, the first relational expression for predicting the arrival time of the S wave obtained from the data of the past large earthquake shown in FIG. The maximum value of the observed waveform of the P wave up to the elapsed time of the elapsed rate with respect to the elapsed rate of the plurality of P waves after the arrival detection (the elapsed time from the time when the P wave was detected until each prediction time / the duration of the P wave) And a second relational expression between the maximum value of the observed waveform of the S wave after the arrival of the S wave. In this embodiment, the P wave arrival detection time is calculated as STA / LTA from the observed waveform of the P wave at each earthquake measurement point, and the time when the threshold value is exceeded for the first time.

  Incidentally, the past major earthquakes shown in FIG. 6 are predicted in the past (for example, a factory where a large number of precision machines that dislike vibrations are installed) from among a plurality of previously generated earthquake data. It was extracted as something that could cause a disaster to be avoided. Specifically, the maximum acceleration value and the measured seismic intensity at the observation point were over a certain value.

  The first relational expression calculates the STA / LTA from the observed waveform of the P wave at each earthquake measurement point from the data of a plurality of large earthquakes shown in FIG. The relationship with the duration of the P wave is obtained.

  Specifically, the premise STA / LTA is the ratio of the short-time moving average STA of the absolute value of the waveform amplitude (acceleration, velocity, displacement, etc.) and the long-time moving average LTA. That is, in the graph of the absolute value of the waveform amplitude with respect to the earthquake shown in FIG. 3A, if the ratio of STA to LTA is calculated and similarly shown on the time axis, it is expressed as shown in FIG. . FIG. 3 shows an example in which the STA moving average interval is 0.1 seconds and the LTA moving average interval is 5.0 seconds with respect to the acceleration amplitude. The technology using STA / LTA is disclosed in Non-Patent Document 1, for example. In the present invention, the maximum value of the STA / LTA is used for prediction of the arrival time of the S wave.

That is, FIG. 7 is a graph showing the STA / LTA for the acceleration waveform of the P wave observed at the occurrence of the large earthquake shown in FIG. 6, and the maximum value and the duration of the P wave at the measurement point. It is a plot.
The maximum value PR _SL of STA / LTA and the P wave duration dT _P (seconds), which is the time from the P wave arrival detection time to the S wave arrival time, are roughly expressed by the following equation. There is a relationship.
dT _P = α ₁ log ₁₀ (PR _SL ) + β ₁
Here, α ₁ and β ₁ are coefficients used for prediction.

Therefore, the coefficients α ₁ and β ₁ are determined from the analysis result of the past earthquake observation record shown in FIG. 7 using the least square method. A curve indicated by a solid line in FIG. 7 indicates the first relational expression thus obtained.

  Further, the second relational expression is an elapsed rate of a plurality of P waves at each large earthquake measurement point shown in FIG. 6 (in this embodiment, as shown in FIG. 8, 0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4 and 1.6), the maximum value of the observed waveform of the P wave and the observed waveform of the S wave up to the elapsed time of the elapsed rate The relationship with the maximum value is shown (see FIG. 5).

More specifically, the strength of the S wave PA _e to be predicted is the time (from the arrival detection time (T _P ) of the P wave to the elapsed rate (P wave elapsed rate L _P ) with respect to the P wave duration ( It is estimated by substituting the maximum value PA of the observed waveform up to T) and the elapsed rate L _P into the following equation.
PA _e = 10 ^ (α ₂ (L _P ) * log ₁₀ (PA) + β ₂ (L _P ))
L _P = (T−T _P ) / (T _Se −T _P )
Here, α ₂ and β ₂ are coefficients used in the prediction formula, and are values determined for each P wave elapsed rate L _P. T _Se is the S wave arrival time predicted using the first relational expression.

FIG. 8 shows the analysis results of the past earthquake observation records shown in FIG. 6, with the horizontal axis PA (maximum acceleration 3 component) and the vertical axis PA _e (acceleration horizontal component of main motion) for each elapsed rate. FIG. 6 shows a relationship diagram up to the time corresponding to each P-wave elapsed rate in the case of the maximum value), and the coefficients α ₂ and β ₂ are determined for each elapsed rate using the least square method. A curve indicated by a solid line in FIG. 8 represents the second relational expression obtained in this way.

Next, an embodiment of a method for predicting the S wave intensity of an earthquake according to the present invention will be described with reference to FIG. 2 together with the function of the waveform processing unit 4 of the PC 2.
First, after the occurrence of an earthquake, when the arrival of the P wave is detected from the waveform information of the vibration sent from the waveform information detection unit 1, the prediction of the strength of the S wave is started. Here, in order to detect the arrival of the P wave, in this embodiment, STA / LTA is calculated from the waveform information, and it is determined that the P wave has arrived when the threshold value is exceeded for the first time.

As the first stage, the arrival time of the S wave is predicted from the waveform information of the P wave. First, the STA / LTA of the observed waveform of the P wave is calculated continuously.
Then, as shown in FIG. 4 (b), the value of STA / LTA of P-wave arrival detection time, and a said first relationship, to calculate the duration dT _P of P-wave arrival S-wave Time T _Se (seconds) is predicted using the following equation.
T _Se = T _P + dT _P
Here, T _P is the P wave arrival detection time (seconds).
Then, as shown in FIG. 4 (c), when the maximum value is obtained from the values of successively obtained STA / LTA, further updates the duration dT _P P wave from the said maximum value and the relationship Thus, a new S wave arrival time T _Se is predicted.

Incidentally, if after detecting a maximum value shown in FIG. 4 (c), if it is greater maximum value is calculated, updates the duration dT _P P wave from again the maximum value and the relationship The process of predicting the arrival time of a new S wave is repeated.
In parallel with this, as the second stage, the P wave elapsed rate L _P (= (T−T _P ) / () from the predicted S wave arrival time T _Se and the arrival detection time of the P wave to the current time T T _Se −T _P )) is calculated.

Next, by using the maximum value PA of the observed waveform up to the time T, the intensity S _e of the S wave to be reached is predicted from the second relational expression at the elapsed rate L _P. Further, information such as the predicted S wave intensity PA _e is displayed on the monitor 5 and output to the recording device 5, and the S wave intensity PA _e exceeds a preset threshold value. At the time, a control command for urgently stopping the production equipment is transmitted from the transmission line 3 to the production equipment or the like to the control signal transmission destination.

  In the above-described embodiment, when the arrival time of the S wave and the strength of the S wave are predicted, only the case where the response acceleration to the earthquake motion is used as an input / output is shown, but the present invention is not limited to this. It is considered that the prediction can be made with the same accuracy even if the response speed to the ground motion or the measured seismic intensity is used. The prediction of the arrival time of the S wave is not limited to that shown in the above embodiment, and can be predicted using, for example, emergency earthquake information.

  As described above, in the method and system for predicting the major dynamic strength of an earthquake having the above-described configuration, the first relational expression is detected after the local seismometer 1 first detects the arrival of the P wave when an earthquake occurs. Is used to predict the arrival time of the S wave, and then continuously measure the P wave, and in the elapsed rate of the P wave from the predicted arrival time of the S wave to the current time, until the elapsed rate is reached. The intensity of the S wave to be reached is predicted from the maximum value of the observed waveform of the P wave observed in the above and the second relational expression.

  For this reason, by using the second relational expression at each elapsed rate stored in the database 6 according to the passage of time of the P wave, various P wave arrival forms such as earthquakes in which the epicenter is far away In addition, it is possible to predict the strength of the S wave with high accuracy even for an earthquake in which the earthquake waveform of the P wave grows over several tens of seconds.

  In addition, when predicting the arrival time of the S wave, as shown in FIG. 6 and FIG. 7 in advance, it was calculated from the observed waveforms of the P wave at each earthquake measurement point from the data of a plurality of past large earthquakes. The relational expression between the maximum value of STA / LTA and the duration of the P wave at the measurement point is obtained, and as shown in FIGS. 4A to 4C, the P wave obtained at the time of the earthquake is observed. Since the STA / LTA is continuously calculated from the waveform and the arrival time of the S wave is predicted from the maximum value and the above relational expression, the arrival time of the S wave is predicted at the initial stage of the earthquake occurrence by simple calculation processing. can do.

  Moreover, the P wave is continuously measured and the STA / LTA is calculated, and the S wave arrival time is updated by updating the duration of the P wave from the maximum value of the STA / LTA obtained in succession and the above relational expression. Predicting the arrival time of S waves with high accuracy not only for short-distance earthquakes but also for long-distance earthquakes where the maximum STA / LTA value is difficult to distinguish. As a result, the prediction accuracy of the intensity of the S wave shown in FIG. 5 can be finally improved.

1 Waveform information detection unit (waveform information detection means)
2 PC (prediction means)
3 Transmission line 4 Waveform processing unit 6 Database

Claims (3)

A method for predicting the main dynamic strength of an earthquake for predicting the intensity of an S wave reaching the site from the observed waveform of the P wave of the earthquake measured at the site to be predicted,
From the data of multiple earthquakes that occurred in the past in advance, the elapsed rate of multiple P waves at each of the earthquake measurement points (elapsed time from the time when the P wave was detected until each predicted time / P wave duration) , A relational expression between the maximum value of the observed waveform of the P wave and the maximum value of the observed waveform of the S wave until the elapsed time of the elapsed rate is obtained,
After the local seismometer detects the arrival of the P wave, the duration of the P wave is predicted, then the P wave is continuously measured, and the progress is sequentially performed at a plurality of elapsed rates of the P wave. A method for predicting the main dynamic strength of an earthquake, which predicts the intensity of the S wave that arrives from the maximum value of the observed waveform of the P wave observed up to the rate and the relational expression. Waveform information detection means for seismic motion installed in the site to be predicted and prediction means for predicting the intensity of the S wave that arrives from the observed waveform of the P wave measured by the waveform information detection means ,
The prediction means is based on the data of a plurality of earthquakes that have occurred in the past, and the elapsed rate of a plurality of P waves at each of the earthquake measurement points (the elapsed time from the time of detection of the arrival of the P wave to the time of each prediction / P wave A database storing a relational expression between the maximum value of the observed waveform of the P wave and the maximum value of the observed waveform of the S wave up to the elapsed time of the elapsed rate calculated for the duration), and the above-mentioned data sent from the waveform information detecting means Based on the observed waveform, the arrival time of the P wave is detected to predict the duration of the P wave, and from the observed waveform of the P wave continuously sent from the waveform information detecting means, at a plurality of elapsed rates of the P wave. And a waveform processing unit for predicting the intensity of the S wave that arrives from the maximum value of the observed waveform of the P wave observed up to the elapsed rate and the relational expression stored in the database. The main of the earthquake characterized by Movement of the strength of the prediction system.   The waveform processing unit sets a threshold for the intensity of the S wave in advance, and outputs a signal to that effect when the intensity of the S wave predicted at the plurality of elapsed rates exceeds the threshold. The system according to claim 2, further comprising a line.

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