JP2010230407A - Earthquake motion predicting system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an earthquake motion predicting system capable of predicting the magnitude, or the like, of an earthquake at site with high accuracy, based on an emergency earthquake alert and an earthquake motion level observed by an on-site seismometer, at an early stage of earthquake generation, even at a spot within several tens of kilometers from the earthquake center. <P>SOLUTION: The system includes an analyzer with which a variance in predicted errors between a prediction value of an earthquake motion level, based on data of the emergency earthquake alert for a plurality of past earthquakes and an actual earthquake motion level observed on site; the variance in predicted errors between a prediction value of an earthquake motion level calculated from data of minor initial tremors observed on site by the seismometer and the actual earthquake motion level are specified; and a first predicted value of the local earthquake motion level based on the data of the emergency earthquake alert and a second predicted value of the local earthquake motion level calculated from the data of the minor initial tremors observed by the seismometer are weighted with the reciprocal ratio of the variance of the predicted error and averaged, to calculate the predicted earthquake motion level. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention predicts the magnitude of local shaking caused by the earthquake based on the earthquake early warning and the level of ground motion observed by the local seismometer before the main motion arrives at the initial stage of the earthquake. This is related to a seismic motion prediction system.

In recent years, the Japan Meteorological Agency's emergency earthquake bulletin has been able to receive information on the magnitude and location of the earthquake that occurred within a few seconds after the earthquake.
And at a point away from the epicenter by several tens of kilometers or more, there is a margin of several seconds to several tens of seconds until the main motion of the ground motion due to the S wave arrives. A technique for preventing occurrence of earthquake damage based on the emergency earthquake information has been proposed.

  However, it is known that such an earthquake early warning is generally inaccurate in the first report and gradually improves as information is updated. For this reason, in the prediction of ground motion using the data of the above earthquake early warnings, although it is possible to take appropriate disaster prevention measures for buildings at points far from the epicenter as described above, There is a problem that high-precision information is not in time for earthquakes that occur at relatively short distances from and from earthquakes that are close to the building, and the desired disaster prevention effect cannot be achieved. .

  That is, in the case of a direct earthquake, it takes about 10 seconds from the occurrence of the earthquake to the arrival of the second emergency earthquake bulletin. For this reason, when the S wave velocity is 3 km / s, the earthquake early warning is not in time at a point 30 km from the epicenter. Therefore, it is possible to use highly accurate emergency earthquake warnings at a point approximately 50 km or more away from the epicenter, but there is a problem that it is difficult to use effectively at a point within about 50 km.

  As a means of solving such problems, a technique has been proposed in which a seismometer is installed on site and the final ground motion level is predicted based on the initial tremor (P wave) of the earthquake observed by the seismometer. .

  And at a point within about 50 km from the above-mentioned epicenter, the predicted value of the ground motion level calculated from the initial tremor observed by the seismometer and the predicted value of the ground motion level from the early earthquake early warning are obtained almost simultaneously. Can do.

  Therefore, in the following Patent Document 2, when an emergency earthquake warning including an S-wave arrival prediction time and a predicted seismic intensity due to the occurrence of an earthquake is sent, whether or not the predicted seismic intensity exceeds a set seismic intensity by receiving the emergency earthquake warning And receiving means for outputting the first determination result and a P-wave seismometer for detecting the P-wave that arrives due to the occurrence of the earthquake, and based on the detection result of the P-wave seismometer, P wave detection means for determining the type of earthquake and predicting and determining the seismic intensity of the S wave scheduled to arrive and outputting a second determination result, and based on the first and second determination results, the S arrival S Confirming whether or not the predicted seismic intensity of the wave exceeds the set value, and determining means for transmitting a trigger signal when the set value exceeds the set value, and starting upon receipt of the trigger signal, before the arrival of the S wave Control the operation or stop of the protection target And an earthquake disaster prevention system characterized by having a control means.

JP 2003-66152 A JP 2007-108012 A

  However, in general, there are prediction errors in the predicted values calculated from the initial tremor observed by the seismometer and the predicted values based on the earthquake early warning, and there are many cases where there is a big gap between the prediction results of the two. On the other hand, in the conventional earthquake disaster prevention system, since both are compared and one is adopted and the other is rejected, for example, many vibration isolating devices such as semiconductor manufacturing factories are used. As with installed structures, it is impossible to respond directly to requests to control the operation of the above equipment by predicting the speed and acceleration of earthquake shaking with high accuracy for disaster prevention. There was a point.

  The present invention has been made in view of the above circumstances, and in particular, even at a point within several tens of kilometers from the epicenter, based on the ground motion level observed by the earthquake early warning and the local seismometer at the initial stage when the earthquake occurred. Thus, an object of the present invention is to provide a seismic motion prediction system capable of predicting the magnitude of local shaking caused by the earthquake with high accuracy.

  In order to solve the above-mentioned problem, the earthquake motion prediction system according to claim 1 is provided with an earthquake early warning receiving means, a seismometer installed in the field, and the local earthquake motion level based on the earthquake early warning data. An analysis device for calculating a predicted earthquake motion level at the local site using the first predicted value of the local motion and the second predicted value of the local ground motion level calculated from the initial tremor data observed by the seismometer. The analysis apparatus comprises a prediction error variance between a predicted value of a ground motion level based on the data of the earthquake early warning at the time of a plurality of past earthquakes and an actual ground motion level observed in the field in advance. The variance of the prediction error between the predicted value of the ground motion level calculated from the initial microtremor data observed by the seismometer and the actual ground motion level is set. Ri, the inverse ratio of the variance of these prediction error by averaging by weighting to the first predicted value and the second predicted values are those characterized by calculating the predicted ground motion levels.

  Here, the level of ground motion is the acceleration, speed, displacement, SI value, measured seismic intensity, or response acceleration of the building.

  The invention according to claim 2 is the invention according to claim 1, wherein the analysis device changes the weighting each time the information of the earthquake early warning is updated to change the predicted ground motion level. Is calculated.

  In the invention described in claim 1 or 2, in the case of a plurality of past earthquakes, the variance of the prediction error between the predicted value of the ground motion level obtained from the earthquake early warning and the actual ground motion level measured in the field And a prediction error between the predicted value of the ground motion level obtained from the initial microtremor data observed by the seismometer and the actual ground motion level, and an urgent The first predicted value of the local ground motion level based on the earthquake early warning and the second predicted value of the local ground motion level calculated from the initial tremor data observed by the seismometer are expressed as the variance of the prediction error. The predicted ground motion level is obtained by weighting with the inverse ratio and averaging.

For this reason, compared with the case where the first predicted value obtained from the earthquake early warning or the second predicted value obtained from the seismometer is used alone, the seismic motion level with high accuracy based on more information is obtained. Predictions can be made.
As a result, it is difficult to use for actual control until now, using information such as the early earthquake early warnings of the first report to the third report, etc., with high accuracy at semiconductor manufacturing plants, etc. It is also possible to respond to a request to control the operation of the devices by predicting the speed and acceleration of shaking.

  Further, according to the invention described in claim 2, since the analysis device calculates the predicted seismic motion level by changing the weighting each time the information of the earthquake early warning is updated, real time The accuracy of the predicted ground motion level due to S waves at the site can be improved.

It is a schematic block diagram which shows one Embodiment of the earthquake motion prediction system which concerns on this invention. It is a block diagram which shows the flow of a process of the data in the analyzer of FIG. It is a time series diagram for demonstrating the prediction method of the prediction ground motion level in the field using the prediction system of FIG. It is a schematic diagram which shows the relationship between the prediction value integrated with the single prediction value. It is a graph which shows the change of the weighting with respect to the predicted value obtained by the earthquake early warning and the local seismometer in this embodiment in time series. It is a figure which shows the distance from a suitable epicenter by applying the earthquake motion prediction system of FIG. It is a graph which shows the Example of this invention.

  FIG. 1 shows a schematic configuration of an embodiment of a ground motion prediction system according to the present invention. Reference numeral 1 in the figure denotes a building (on-site) such as a semiconductor manufacturing factory in which the system is installed. In the building 1, many facility devices (only one of them is shown in the figure) 2 that dislikes vibration are installed.

  And in this building 1, the seismometer 3 for detecting the level P of a ground motion is attached. Here, as the level of seismic motion detected and output by the seismometer 3, it is possible to apply acceleration, velocity, displacement, SI value or measured seismic intensity, or a combination thereof. In the present embodiment, the case where the measured seismic intensity is used as the above-mentioned ground motion level will be described below.

  Further, in this building 1, data from the receiving means 4 for the earthquake early warning for advanced users and data from the seismometer 3 are inputted, and the magnitude of shaking in the building 1 is predicted based on these data. An analysis device 5 is installed.

As shown in FIG. 4, the analysis device 5 includes an earthquake motion level predicted value x _0e based on emergency earthquake early warning data at the time of a plurality of past earthquakes and an actual earthquake motion level x _obs observed in the building 1. The standard deviation (variance) σ ₀ of the mean value Δx ₀ of the prediction error during the period and the actual value x ₁ of the ground motion level calculated from the initial tremor (P wave) data observed at the building 1 by the seismometer 3 and the actual value The standard deviation (variance) σ of the prediction error between the seismic motion level x _obs is set.

Further, in this analysis device 5, data of the magnitude M of the earthquake that occurred, the latitude and longitude of the earthquake occurrence location, and the depth D, which are input as emergency earthquake information for advanced users when a new earthquake occurs, and the building 1 An arithmetic circuit for calculating a predicted value x _0e of the ground motion level of the building 1 using an empirical formula such as a distance attenuation formula from the distance X from the to the epicenter is incorporated.

In addition, when a new earthquake occurs, the second predicted value x ₁ of the ground motion level in the building ₁ is calculated from the initial tremor (P wave) data observed in the building 1 by the seismometer 3 using a prediction formula. Arithmetic circuit is incorporated. In addition, as said prediction formula, the prediction formula statistically obtained from many past earthquakes, or the prediction formula by analysis can be used.

  Incidentally, for example, Wu, Y.-M. and Kanamori, H. (2005): Rapid Assessment of Damage Potential of Earthquakes in Taiwan from the Beginning of The prediction formula disclosed in P Waves, Bulletin of the Seismological Society of America, Volume 95, Number 3, pp. 1181-1185 can be applied.

In the analysis device 5, as shown in FIGS. 2 and 3, when an earthquake occurs, for example, when the second report of the early earthquake early warning is received, the ground motion level of the building 1 calculated from the emergency earthquake information is received. average prediction error first predicted value x ₀ which corrected [Delta] x and _{(x 0e + Δx = x 0} ), preliminary tremor (P wave observed in the building 1 by seismometer 3 to the first predicted value x _0e of from the data to the second predicted value x ₁ of the ground motion level in the building 1 using a prediction equation of), the predicted seismic motion are integrated by averaging by weighting by the inverse ratio of the variance of the prediction error by the following formula 1 An arithmetic circuit for calculating level x ₂ is incorporated.

In this analysis device 5, as shown in FIG. 5, every time the information on the emergency earthquake warning is updated as the first report, the second report, and the third report, the above-described calculation is performed each time, The predicted ground motion level x ₂ is calculated by changing the weighting shown in 1 and averaging.

According to the earthquake motion prediction system configured as described above, the first predicted value x ₀ obtained from the earthquake early warning and the second predicted value x ₁ obtained from the seismometer 3 are compared with the case of using alone. Thus, it is possible to predict the ground motion level with high accuracy based on more information.
That is, there is a prediction error between the predicted value x _0e of the ground motion level based on the data of the emergency earthquake early warning at the time of a plurality of past earthquakes and the actual ground motion level x _obs observed in the building 1. The probability density distribution of the prediction error is assumed to be a normal distribution N (Δx ₀ , σ ₀ ) (x _0e + Δx ₀ = x ₀ ). At this time, the prior probability distribution p ₀ (x _obs ) of the observed value x _obs observed when a new earthquake occurs can be represented by a normal distribution N (x ₀ , σ ₀ ) indicated by a in FIG.

On the other hand, if the ground motion level of the main motion is x _obs from the relationship between the initial tremor and the main motion at the time of a plurality of past earthquakes, the probability distribution p (x ₁₎ of the ground motion level x ₁ of the main motion predicted from the initial tremor. | X _obs ) can be represented by a normal distribution N (x _obs , σ) indicated by b in FIG. Here, the relationship between the initial tremor and the main motion can be obtained from a plurality of past earthquake data in the seismometer 3 of the building 1 and past earthquake data in various parts of Japan.
In the present embodiment, it is assumed that the prediction between the ground motion level x _{obs of the} main motion and the predicted value x ₁ by the seismometer is appropriately made and there is no average deviation.
As described above, when a new earthquake occurs, the ground motion level x _obs of the main motion is predicted with the probability distribution p ₀ (x _obs ) by the emergency earthquake warning, and then the ground motion level x of the main motion from the initial microtremor observed by the seismometer 3. _{When obs} is predicted to be x ₁ , the probability distribution p1 (x _obs | x ₁ ) of the main ground motion level x _obs predicted from the earthquake early warning and the local seismometer is

The probability distribution p ₁ (x _obs | x ₁ ) is a normal distribution N (x ₂ , σ ₂ ) as indicated by c in FIG. Here, x ₂ is as shown in Equation 1 above, and is σ ₂ = σ · σ ₀ / (σ ² + σ ₀ ² ) ^1/2 .
From FIG. 4, it was based on more information compared with the case where the first predicted value x ₀ obtained from the earthquake early warning and the second predicted value x ₁ obtained from the seismometer 3 are used alone. It can be seen that the earthquake motion level can be predicted with high accuracy.

  As a result, as shown in FIG. 6, the first report to the first report in the initial stage at the time of the earthquake, especially at a point within tens of kilometers from the epicenter, which has been difficult to use for actual control until now. Based on the early earthquake early warning of about 3 earthquakes and the ground motion level observed by the local seismometer, it is possible to predict the magnitude of the local shaking caused by the above earthquake with high accuracy. It is possible to respond to a request to control the operation of the devices by predicting the speed and acceleration of shaking with high accuracy in a manufacturing factory or the like.

  FIG. 7 shows the seismic intensity predicted value based on the emergency earthquake bulletin, the local earthquake based on the records observed in Niigata Prefecture during the 2007 Chuetsu-Oki Earthquake in 2007 to confirm the effect of the earthquake motion prediction system according to the present invention. The predicted values of seismic intensity based on the totals and the predicted values of seismic intensity according to the present invention weighted and averaged for these are shown in comparison with the observed actual seismic intensity.

  From the figure, in the predicted values based on the earthquake early warning, the seismic intensity higher than the actual seismic intensity was predicted from the second report onwards, and gradually became closer to the actual seismic intensity as it was updated. It can be seen that it took more than 15 seconds to complete. On the other hand, the predicted value by the local seismometer is a predicted value lower than the actual seismic intensity from the beginning, and similarly it takes 15 seconds or more to reach a predicted value close to the actual seismic intensity.

  On the other hand, with the predicted value according to the present invention, it can be seen that a predicted value almost similar to the actual seismic intensity can be obtained from the beginning when the local seismometer observed the initial tremor of the earthquake.

  Used to predict the magnitude of local shaking caused by the earthquake based on the earthquake early warning and the level of ground motion observed by the local seismometer before the main motion arrives at the initial stage of the earthquake. Is done.

1 building (local)
3 Seismometer 4 Receiving means for earthquake early warning 5 Analyzing device

Claims (2)

From the means for receiving the earthquake early warning, the seismometer installed in the field, the first predicted value of the ground motion level based on the data of the earthquake early warning and the data of the initial tremor observed by the seismometer An analysis device that calculates the predicted earthquake motion level at the site using the calculated second predicted value of the earthquake motion level at the site,
The analysis apparatus includes a variance of a prediction error between a predicted value of a ground motion level based on the data of the earthquake early warning at the time of a plurality of past earthquakes and an actual ground motion level observed in the field, and the seismometer The variance of the prediction error between the predicted value of the ground motion level calculated from the initial microtremor data observed at the site and the actual ground motion level is set. An earthquake prediction system, wherein the predicted earthquake motion level is calculated by weighting and averaging the predicted value of 1 and the second predicted value.   2. The earthquake prediction system according to claim 1, wherein the analysis device calculates the predicted earthquake motion level by changing the weighting each time the information of the earthquake early warning is updated. 3.

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