JPS59195178A - Earthquake deciding method - Google Patents

Abstract

PURPOSE:To enable decision of the time when an earthquake wave arises with high accuracy by making use of a decision by a high speed Fourier transformation in combination with a decision by a moving average. CONSTITUTION:The observation signals from a seimsograph EQ and a telemeter device TM are collected in a center DTC and is subjected to an A/D conversion by a receiver TRV, from which the signal is supplied to a moving average processing circuit TD and a high speed Fourier transformation processing circuit FFT. An integrated amplitude value A1 and an integrated amplitude value A2 at a noise level are compared when the signal exceeding a threshold level with respect to the frequency level W1-W2 specific to the earthquake wave is inputted are compared and the time t0 when (A2Xbeta)<A1 is attained is decided as the time when the earthquake arises.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to a method for determining the time of seismic wave generation with high precision.

(2) Conventional technology and problems Conventionally, in order to determine the time of earthquake onset, observation signals from multiple seismic wave observation telemeter devices are collected at a data center, and the time of earthquake wave occurrence is determined using the moving average method. Was. In other words, as shown in Figure 1, when converting seismic waves to voltage levels and observing them, ao
-Ar46 average voltage level a1 and a long time of about 40 seconds, +. ~ba is compared with the end of the average value, and the start time of any of the short periods aw ""' ao when bt-xα<aL is determined to be the time of seismic wave generation. However, α is an arbitrary constant larger than l, and is selected in accordance with the magnitude of earthquakes that are likely to occur. In Figure 1, aQ, o+ a,')
・When ao exceeds a predetermined threshold level, the long-term average value bL does not change rapidly, so the short-term a. The average value of is suddenly thicker (changes). In this case, it is difficult to obtain theoretically appropriate values for the length of time and the size of α, and appropriate values are used based on experience. Was.

It is also being considered that it would be better to determine α in response to weather changes. Therefore, there is a drawback that the accuracy of the start time of the short time ao is not high.

(3) Purpose of the Invention The purpose of the present invention is to improve the above-mentioned drawbacks and to provide a method for determining the time of seismic wave generation with high accuracy by also performing subsequent data processing.

4) Structure of the Invention The structure of the present invention to achieve the above-mentioned object is to collect observation signals from a seismic wave observation telemeter device in a data center and determine whether or not an earthquake has occurred. , always perform fast Fourier transform and the judgment results and 1. The method is to use both the determination results based on the moving average and determine the time of seismic wave generation when both detect the occurrence of an earthquake.

(Embodiment 5 of the Invention Figure 2 is a diagram showing the configuration of an embodiment of the invention.
View from Q and its telemeter device TM/l! 11 signals are collected at the data center DTC. Data center DTC
Now, the telemeter receiving device TRV performs A/D conversion, and a determination is made on the obtained digital signal. Moving average processing circuit T using the above-mentioned moving average method
D and is input to the fast Fourier transform processing circuit FFT according to the present invention.

The fast Fourier transform process is to obtain the frequency versus amplitude value for the tagged signal at the given time, as shown in FIGS. 3A and 3B. Ikuji seismic wave patent frequency range W1 ~
Regarding W2, when a signal exceeding the threshold level as shown in FIG. 3A is input, the amplitude integral value A
1 and the amplitude integral value A2 at time t1 at the so-called normal noise level shown in FIG. 3B are compared. Then, the time 10 when A2Xβ<Al (where β is an arbitrary constant greater than 1) is determined to be the time of seismic wave generation. When the central processing unit CPU detects the occurrence of seismic waves using the same moving average method as described above and further detects the occurrence of seismic waves using the FFT method, it determines that a true seismic wave has occurred, and at this time, the time of earthquake occurrence is determined using the moving average method. Either the time or the time determined by the FFT method may be used.

(6) Effects of the Invention As described above, according to the present invention, by using determination by fast Fourier transform together with determination by conventional moving average, when determining seismic waves from different points, geological conditions along the way can be , it is possible to reduce errors based on weather conditions, to obtain highly accurate seismic wave generation times, and therefore to more accurately determine earthquake occurrence points.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram for determining seismic waves using the moving average method. FIG. 2 is an illustration of the configuration of an embodiment of the present invention. FIG. 3 is an explanatory diagram of fast Fourier transform processing. 'T'RV - Moving average processing circuit F F T - Fast Fourier transform processing circuit CP U - Central processing unit Patent applicant Fujitsu Co., Ltd. Agent Patent attorney Eisuke Suzuki A Figure 1

Claims (1)

[Claims] In an earthquake determination method that collects observation signals from seismic wave observation telemeter equipment in a data center and determines the occurrence of an earthquake, the observation signals are constantly subjected to fast Fourier transform and the determination results are combined with the determination results based on a moving average. An earthquake determination method characterized by being used together to determine the time of seismic wave generation when earthquakes are detected by both.