JP2006275696A - Early earthquake specification estimation method and its system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an early earthquake specification estimation method and its system surely and earlier estimating earthquake specifications by using one second data after arrival of P wave. <P>SOLUTION: According to: one second data of coefficient B obtained by the function fitting method which represents the rate of time variation of the initial amplitude; the maximum amplitude of early minute vibration (one sec. A<SB>max</SB>) of one second after arrival of P wave; and the equation of the epicentral distance logΔ=(one sec. B)+β, the magnitude M is estimated as follows: M=αlog(one sec. A<SB>max</SB>)+βlog(one sec. B)+γ+k, (where α, β, and γ are determined statistically, and k is a constant number). Thereby, the specification of the earthquake is surely estimated earlier by using the one second data after arrival of P wave. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an early earthquake specification estimation method, and more particularly to an early earthquake specification estimation method and system for estimating an earthquake specification (an epicenter distance and magnitude) using data for 1 second from arrival of a P wave. is there.

In order to estimate the epicenter distance and magnitude, the inventors of the present application have already fitted the waveform shape of the initial motion part of the seismic wave with a few simple functions to quantify the waveform shape, and from the obtained parameters An epicenter distance and magnitude estimation method that can estimate the epicenter distance and magnitude has been proposed (see Patent Documents 1 and 2 below).
JP 2002-277557 A JP 2005-010041 A

  Using the function fitting method, which is the above-mentioned earthquake specification estimation method, the inventors of this application have proposed to estimate the earthquake specification using data for 2 seconds from the arrival of the P wave. In earthquakes and the like, an early method for estimating earthquake specifications has been demanded.

  In view of the above situation, the present invention provides an early earthquake specification estimation method and system capable of accurately estimating an earthquake specification more quickly using data for 1 second after arrival of a P wave. Objective.

In order to achieve the above object, the present invention provides
[1] In the early earthquake specifications estimation method, the 1-second data (1 second B) of the coefficient B representing the degree of temporal change of the P-wave initial motion amplitude obtained by using the function fitting method, and the 1-second data from the arrival of the P-wave From the maximum amplitude of the initial tremor (1 second A _max ), the epicenter distance is based on log Δ = α log (1 second B) + β, and the magnitude is M = α log (1 second A _max ) + β log (1 second B) + γ + k ( α, β, and γ are coefficients determined statistically, and k is a constant).

  [2] In the early earthquake specification estimating method according to [1], the k is a constant and is set to 0.3 to 0.7.

  [3] In the early earthquake specification estimating method according to [2], the k is set to 0.5.

[4] In the early earthquake data estimation system, the coefficient B for 1 second is used to calculate the coefficient B representing the degree of time change of the P wave initial motion amplitude for 1 second by the function fitting method based on the information from the seismometer and the seismometer. A calculation unit, an epicenter distance estimation unit that estimates the epicenter distance based on the one-second coefficient B, a maximum amplitude calculation unit that obtains a maximum amplitude (1 second A _max ) from the arrival of the P wave, and the maximum And a magnitude estimating unit for estimating a magnitude based on the amplitude, the coefficient B for one second, and the constant k.

  According to the present invention, it is possible to quickly and accurately estimate the specifications of a direct type earthquake using data for one second from the arrival of the P wave, and to minimize the damage caused by the accident.

The early earthquake specification estimation method and system according to the present invention include 1 second data (1 second B) of coefficient B representing the degree of temporal change in P wave initial motion amplitude obtained using the function fitting method, and the arrival of the P wave. From the maximum amplitude (1 second A _max ) of the initial tremor for 1 second, the epicenter distance is based on log Δ = α log (1 second B) + β, and the magnitude is M = α log (1 second A _max ) + β log (1 second B) ) + Γ + k (α, β, γ are coefficients determined statistically, and k is a constant). Therefore, it will quickly and accurately estimate the specifications of the direct type earthquake and minimize the damage caused by the accident.

  Hereinafter, embodiments of the present invention will be described in detail.

  FIG. 1 is a diagram showing an early earthquake specification estimating system showing an embodiment of the present invention.

In this figure, 1 is a seismometer, 2 is an input unit for a constant k, 3 is an information processing device, 4 is a 1-second coefficient B (1 second) indicating the degree of temporal change in P-wave initial motion amplitude for 1 second by the function fitting method. B) a calculation unit, 5 is an epicenter distance estimation unit based on the 1-second coefficient B (1 second B), 6 is a detection unit of the maximum amplitude A _max (1 second A _max ) for 1 second from the arrival of the P wave, 7 is a magnitude estimation unit based on the maximum amplitude A _max (1 second A _max ), 1 second coefficient B (1 second B) and a constant k from the arrival of the P wave, and 8 is an epicenter distance and magnitude estimation. A value transmission unit 9 is a communication line through which the epicenter distance and the estimated value of the magnitude are transmitted.

In this early earthquake specification estimation system, first, the function fitting method (see Patent Document 1 above) is used based on the earthquake information obtained from the seismometer 1 in the calculation unit 4 of the coefficient B (1 second B) for 1 second. Then, a 1-second coefficient B (1 second B) indicating the degree of time change of the P wave initial motion amplitude for 1 second is calculated. Next, the epicenter distance is estimated by the epicenter distance estimation unit 5 based on the obtained one-second coefficient B (1 second B). On the other hand, by the detection unit 6 of the maximum amplitude A _max 1 second (1 sec A _max), determine the maximum amplitude A _max of one second from the P-wave arrival (second A _max), said one second coefficient B (1 sec B ) And the constant k input from the constant k input unit 2, the magnitude estimation unit 7 estimates the magnitude. The estimated epicenter distance and magnitude estimated value thus obtained are transmitted from the transmitter 8 to the earthquake information center (not shown) via the communication line 9 in real time.

  A specific epicenter distance and magnitude estimation method will be described.

(1) Estimation of epicenter distance Based on the function fitting method, the data for one second from the arrival of the P wave is applied to the following formula (1) to estimate the epicenter distance.

log Δ = α log (1 second B) + β (1)
Here, α and β are coefficients determined statistically.

(2) Magnitude estimation Based on the function fitting method, the magnitude is calculated from the coefficient B (1 second B) obtained using the data for 1 second from the arrival of the P wave and the maximum amplitude of ground motion (1 second A _max ) for 1 second. presume.

M = α log (1 second A _max ) + β log (1 second B) + γ (2)
α, β, and γ are statistically determined coefficients.

  In the following, the epicenter distance and magnitude estimation will be described by applying actual data.

(1) Estimation of epicenter distance In the conventional early earthquake specifications estimation method (the above-mentioned patent documents 1 and 2), as shown in FIG. 2, the P wave initial motion is applied to the following equation (3), and coefficients A and B And the epicenter distance is estimated from the relationship between the coefficient B corresponding to the increase rate of the amplitude of the P wave initial motion and the epicenter distance.

y (t) = Bt × exp (−At) (3)
However, t is a time when the arrival time of the P wave is 0, and coefficients A and B are parameters obtained by fitting a function.

  Here, the relationship between the actual epicenter distance is compared with the coefficient B (referred to as 1 second B and 2 seconds B, respectively) obtained using the data for 1 second and 2 seconds from the arrival of the P wave. Verify the accuracy of the estimation.

  The data to be analyzed is a total of 588 observation points of strong motion records obtained with the Japan Meteorological Agency Type 95 seismometer. The magnitude range of the earthquake is M2.8 to M7.3.

  FIG. 3 shows the relationship between the epicenter distance of 1 second B and 2 seconds B. Although there is a difference between 1 second B (indicated by Δ) and 2 seconds B (indicated by □) for individual data, the overall trend has a negative correlation with the epicenter distance. In FIG. 3, the broken line indicates the following formula (4).

  Next, the estimation accuracy at 1 second B is verified from the difference between the epicenter distance estimated by applying the estimation formula created to estimate the epicenter distance from 2 seconds B to 1 second B and the actual epicenter distance.

  The epicenter distance estimation formula using 2 seconds B can be expressed as follows.

log Δ = −0.498 · log (2 seconds B) +1.965 (4)
However, (DELTA) is an estimated epicenter distance (km) and the unit of 2 second B is gal / s.

  Therefore, FIG. 4 shows the estimated accuracy of the estimated epicenter distance obtained by substituting the value of 1 second B into the 2 second B term of the above equation (4). About 75% of the target 588 data is within the range of half the actual epicenter distance (range of -0.3 to 0.3 on the horizontal axis in Fig. 4), and the epicenter distance at 2 seconds B It can be seen that the estimation accuracy is almost the same.

(2) Magnitude estimation Magnitude is estimated using the following statistical formula using the maximum displacement amplitude (referred to as 1 second A _max ) and 1 second B of vertical movement for 1 second from P-wave measurement.

M = α log (1 second A _max ) + β log (1 second B) + γ (5)
Where M is the estimated magnitude, 1 second A _max is the maximum vertical displacement (cm) for 1 second from the P-wave detection, and α, β, and γ are statistically obtained coefficients.

FIG. 5 shows the relationship between the epicenter distance and 1 second A _max for each magnitude. Here, ■ is M (magnitude) 7, ▲ is M6, ◇ is M5, ▽ is M4, and □ is M3.

Looking at each magnitude, as the epicenter distance increases (that is, as 1 second B decreases), 1 second A _max tends to decrease with some variation. In addition, the relationship between the epicenter distance and A _max (the following equation (6)) using the statistical formula for magnitude estimation after 2 seconds is shown by a broken line in FIG.

M = 0.7387 · log (A _max ) −1.02 · log (B) +7.07 (6)
However, in FIG. 5, the relationship between the coefficient 1 second B and the epicenter distance is converted using the above equation (4).

  Here, the earthquake that is the target of earthquake specification estimation is “Earthquake distance 30 km that can be covered by setting M ≧ 5.5, which is the lower limit of magnitude that may cause damage, and 1 second B ≧ 1 gal / s” FIG. 6 shows the magnitude estimation accuracy using the above equation (6) in the case of “inside earthquake”. The above data is 22 of 588 data, and the magnitude is underestimated in all the data.

  This is because the estimation formula shown in the above formula (6) was originally created from the relationship between the maximum vertical displacement for 3 seconds and the magnitude from the P-wave detection, and the number of data was further increased. However, the trend of underestimation is not changed.

However, as shown in FIG. 5, since the slope of the distance attenuation at 1 second A _max is the same as that in the above equation (6), the magnitude estimation equation for 1 second A _max with higher accuracy is as follows. Can be created by adding a constant to the estimation formula of the above formula (6).

M = 0.7387 · log (A _max ) −1.02 · log (B) + 7.07 + k (constant) (7)
Here, k is a constant. In addition, this constant increases the accuracy of estimating the magnitude from the data for 1 second by setting k in the range of 0.3 to 0.7 (provisional value is 0.5) from the error frequency distribution of FIG. .

  In addition, this invention is not limited to the said Example, A various deformation | transformation is possible based on the meaning of this invention, and these are not excluded from the scope of the present invention.

  The early earthquake specification estimation method and system of the present invention can be used as an early earthquake specification estimation method that can cope with a direct type earthquake.

It is a figure which shows the early earthquake item estimation system which shows the Example of this invention. It is an outline explanatory view of a function fitting method. It is a figure which shows the relationship between the coefficient B (1 second B, 2 second B) and epicenter distance in a function fitting method. It is a figure which shows the estimation accuracy of the epicenter distance by 1 second B. FIG. It is a figure which shows the relationship between epicenter distance and 1 second _Amax . It is a figure which shows the magnitude | size estimation precision by an estimation formula (6).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Seismometer 2 Input part of constant k 3 Information processing device 4 Calculation part of coefficient B for 1 second 5 Estimation part of epicenter distance based on coefficient B for 1 second 6 Detection part of maximum amplitude A _max for 1 second from arrival of P wave 7 Magnitude estimation unit based on maximum amplitude A _max , 1-second coefficient B, and constant k 8 Epicenter distance and magnitude estimation value transmission unit 9 Communication line

Claims (4)

1 second data (1 second B) of coefficient B representing the degree of time change of the P wave initial motion amplitude obtained using the function fitting method, and the maximum amplitude (1 second A _max ) of initial fine motion for 1 second from the arrival of the P wave. From the epicenter distance, log Δ = α log (1 second B) + β, and the magnitude M = α log (1 second A _max ) + β log (1 second B) + γ + k (α, β, γ are coefficients that are statistically determined. , K is a constant).   2. The early earthquake specification estimating method according to claim 1, wherein k is a constant and is set to 0.3 to 0.7.   3. The early earthquake specification estimation method according to claim 2, wherein k is set to 0.5. (A) a seismometer;
(B) a calculation unit for a coefficient B for 1 second for calculating a coefficient B representing the degree of temporal change of the P wave initial motion amplitude for 1 second by the function fitting method based on information from the seismometer;
(C) an epicenter distance estimation unit for estimating an epicenter distance based on the one-second coefficient B;
(D) a maximum amplitude calculation unit for _obtaining a maximum amplitude (1 second A _max ) for 1 second from the arrival of the P wave;
(E) An early earthquake specification estimating system comprising: a magnitude estimating unit that estimates a magnitude based on the maximum amplitude, the 1 second coefficient 1 second B, and a constant k.

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