JPH02309284A - Seismic intensity meter - Google Patents

Abstract

PURPOSE:To display a seismic intensity definitely by a method wherein an acceleration is detected by a plurality of acceleration sensors, only a frequency component being in accord with the period of an earthquake is passed by band- pass filters, each acceleration signal is averaged, each acceleration signal is synthesized, and the seismic intensity is determined from the magnitude of a resultant acceleration on the basis of a seismic intensity table. CONSTITUTION:Band-pass filters 24x, 24y and 24z pass only seismic waves. Integrating elements 30x, 30y and 30z integrate signals rectified by absolute value elements 28x, 28y and 28z, at a prescribed period. Digital signals stored in memories 34x, 34y and 34z are averaged for a prescribed term by averaging elements 36x, 36y and 36z and average signals X, Y and Z are outputted therefrom. An arithmetic element 38 computes the magnitude of a resultant acceleration. By means of a comparator element 40 and a seismic intensity table 42, a seismic intensity is determined from the magnitude of the resultant acceleration.

Description

[Detailed Description of the Invention] [Summary] Regarding a seismic intensity meter that detects the seismic intensity of an earthquake, the purpose is to provide an inexpensive and small seismic intensity meter that can easily measure seismic intensity. an acceleration sensor, a plurality of bandpass filters that pass only frequency components that match the earthquake period in each acceleration signal of the plurality of acceleration sensors, and a plurality of bandpass filters that average the acceleration signals that have passed through the plurality of bandpass filters. an acceleration calculation unit that calculates the magnitude of a composite acceleration obtained by combining each acceleration signal averaged by the plurality of averaging units, and a seismic intensity table that stores the relationship between seismic intensity and acceleration of an earthquake. and a seismic intensity determination unit that determines seismic intensity from the magnitude of the composite acceleration calculated by the calculation unit based on the seismic intensity table, and a display unit that displays the seismic intensity determined by the seismic intensity determination unit. Configure.

[Industrial application field] The present invention relates to a seismic intensity meter that detects the seismic intensity of an earthquake.

The strength of an earthquake is expressed in seven levels, from intensity 1 (minor earthquake) to intensity 7 (severe earthquake), and is determined by the sensation felt by the human body and the degree of impact on buildings. originally,
People's interest in earthquakes is extremely strong, and there is a strong demand for a seismic intensity meter that can easily measure seismic intensity at low cost from the perspective of earthquake disaster prevention.

[Prior Art] The seismic intensity of an earthquake is not determined solely by quantitative measurements, but is ultimately determined based on the sensations experienced by the human body and the degree of impact on buildings.

However, there is a general correspondence between seismic intensity and maximum acceleration, and the Japan Meteorological Agency also determines seismic intensity based on the values of seismic intensity meters.

On the other hand, in households and schools, it is necessary to immediately judge the magnitude of an earthquake and take disaster prevention measures before the official announcement of the seismic intensity from the Japan Meteorological Agency, and there is a strong desire for a seismic intensity meter that can make quantitative judgments. be.

However, while conventional seismic intensity meters can accurately measure the magnitude of earthquakes, they are large and extremely expensive, making it impossible for ordinary households, schools, etc. to purchase them and measure the seismic intensity at f@Jit.

[Problem to be solved by the invention] As described above, conventional seismic intensity meters have only been expensive and large-sized ones that are reserved for specialized organizations such as the Japan Meteorological Agency, and are not suitable for taking prompt earthquake countermeasures in ordinary homes, schools, etc. It was a problem.

The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide an inexpensive and small-sized seismic intensity meter that can easily measure seismic intensity.

[Means for Solving the Problem] The above object is to provide a plurality of acceleration sensors that detect acceleration in directions orthogonal to each other, and to pass only frequency components that match the earthquake period in each acceleration signal of the plurality of acceleration sensors. a plurality of bandpass filters, a plurality of averaging sections that average the respective acceleration signals that have passed through the plurality of bandpass filters, and a composite acceleration obtained by combining the respective acceleration signals averaged by the plurality of averaging sections. an acceleration calculation unit that calculates the magnitude of the earthquake, a seismic intensity table that stores the relationship between seismic intensity and acceleration, and a seismic intensity that is determined from the magnitude of the composite acceleration calculated by the calculation unit based on the seismic intensity table. This is achieved by a seismic intensity meter characterized by comprising: a seismic intensity determination section that performs the seismic intensity determination section; and a display section that displays the seismic intensity determined by the seismic intensity determination section.

[Operation] According to the present invention, acceleration is detected by a plurality of acceleration sensors, only frequency components matching the earthquake period in each acceleration signal are passed through a bandpass filter, and each acceleration signal is averaged by an averaging section. , an acceleration calculation unit combines each acceleration signal and calculates the magnitude of the combined acceleration. The seismic intensity is determined from the magnitude of the composite acceleration based on the seismic intensity table in which the relationship between the seismic intensity and acceleration of an earthquake is stored, and the determined seismic intensity is displayed on the display unit.

[Example] A seismic intensity meter according to a first example of the present invention will be described with reference to FIGS. 1 to 4.

As shown in FIG. 1, the seismic intensity meter of this embodiment is provided with a power switch 12 on the side surface of a housing 10 for turning the power on and off. Further, a display section 14 of, for example, a liquid crystal is provided at the upper front of the housing 10, and at the bottom of the display section 14 there is a clear switch 16 for clearing the seismic intensity information, and a clear switch 16 for clearing seismic intensity information, and a maximum ffi (HAXIHU14) instantaneous 1i [ff (
A changeover switch 18 is provided to change over the TEHPOR.

The acceleration sensor 20, which is the heart of the seismic intensity meter, uses a so-called barber pole type magnetoresistive element described in Japanese Patent Application No. 110882/1982 by the same applicant. The external appearance of the acceleration sensor 20 is shown in FIG. 2, and the functional blocks are shown in FIG.

A magnet 20b is attached to the movable end of the cantilever beam 20a, and magnetic resistance elements 20c and 20d are provided on both sides of the magnet 20b. The signals from the magnetoresistive elements 20c and 20d are added with opposite polarities by an adding section 20e, as shown in FIG. When the magnet 20b is displaced by application of acceleration, it approaches one of the magnetoresistive elements 20c and 20d and moves away from the other.

By adding these signals in the adder 20e, it is possible to cancel the influence of disturbances and obtain a necessary acceleration signal.

Therefore, the vibration direction of the magnet 20b becomes the acceleration detection direction. As shown in FIG. 2, the main body of the acceleration sensor 20 is formed on a base 2Of, and the entire body is covered with a cap 20g.

In the seismic intensity meter of this embodiment, acceleration sensors 20x, 20y, and 2oz in the X, y, and z directions are housed in a housing 10. The acceleration detection directions of each of the acceleration sensors 20x, 20y, and 20z are orthogonal to each other in the X-axis direction, y-axis direction, and Z-axis direction, respectively, as shown by broken line arrows in FIG.

FIG. 4 shows the functional blocks of the seismic intensity meter of this embodiment.

Acceleration sensor 20K in X-axis direction, Y-axis direction, Z-axis direction
, 20y, and 20z are each provided with a circuit for processing an output signal. That is, acceleration sensor 2
Amplifiers 22x and 22 for 0x, 20y, and 20z, respectively.
y, 22Z, bandpass filter 24x, 24y, 2
4z1 amplifiers 26x, 26y, and 26z are provided. The bandpass filters 24x, 24y, and 24z are designed to pass only seismic waves at intervals of 0, 1 to ICH, which is the period of the earthquake.
This is a bandpass filter that passes only the frequency components that match Iz. First stage Anne 122x, 22y,
For example, if the amplification factor of 22z is 54 dB, the second stage amplifier 2
For example, if the amplification factors of 6x, 26y, and 26z are 26dB,
The total amplification factor is 80 dB.

In addition, as shown in FIG. 4, the amplifiers 26x, 26y, 2
Since the output signal of 6z is a raw seismic wave signal, it can be monitored externally if necessary.

The amplifiers 26x, 26y, and 26z are provided with absolute value sections 28x, 28y, and 28z, respectively.
For example, amplifiers 26x, 26y, 26
Cut the negative part of the output signal of z or invert the sign of the negative part.

Integrating parts 30x, 30y, 30z are absolute value parts 28x, 2
The signals rectified by 8y and 28z are integrated at a predetermined period, for example, at a 1/60 second period.

The A/D conversion sections 32x, 32y, and 32z are the integration section 30
Analog signals output from x, 30y, and 30z are converted into digital signals and stored in memories 34x, 34y, and 34z. In this embodiment, 60 digital signals are generated per second and stored in the memories 34X, 34y, and 34z.

Since the digital signals stored in the memories 34x, 34y, and 34z vary over time, the averaging units 36x, 36
y, 36z over a predetermined period to obtain an averaged signal
, Y, and Z. For example, in this practical example, digital signals for 10 seconds are averaged.

The calculation unit 38 calculates the magnitude R of the composite acceleration based on the averaged signals X, Y, and Z from the averaging units 36x, 36y, and 362.
is calculated using the following formula.

The comparison unit 40 and the seismic intensity table 42 constitute a seismic intensity determination unit that determines the seismic intensity from the magnitude of the composite acceleration. That is, the comparison unit 40 determines the seismic intensity by ratioing the magnitude R of the resultant acceleration and the seismic intensity table 42. Seismic intensity table 42
is a memorization of the relationship between the seismic intensity and acceleration of an earthquake, and is as follows (see Physical and Chemistry Dictionary).

Seismic intensity 0: O~2.5ci/s2 Penetration 2=
2°5~8 cn/s2 seismic intensity 3:8
~25 ctg/s2 seismic intensity 4: 25 ~
80 cn/s2 Seismic intensity 5 = 80 ~ 250
cn/s2 seismic intensity 6: 250 to 400 c
n/s2 seismic intensity 7=400 to cl/s2 It is determined to which seismic intensity in the seismic intensity table 42 the magnitude R of the composite acceleration corresponds and is output.

The maximum seismic intensity value of the seismic intensity signal outputted from the comparison section 40 is held by the peak hold section 44 . The maximum seismic intensity value held in this peak hold section 44 is determined by the clear switch 16
Cleared by pressing .

Maximum [(HAXIHklM) instantaneous value (TEMPOR
ARY) The changeover switch 18 for all switching is the comparison section 40.
The seismic intensity signal output from the peak hold section 44 and the maximum seismic intensity value output from the peak hold section 44 are switched. The seismic intensity signal from the comparison section 40 is switched as an instantaneous value (TEHPORARY), and the maximum seismic intensity value from the peak hold section 44 is changed to the maximum value (TEHPORARY).
HAXI14UH).

The signal switched by the changeover switch 18 is displayed on the display section 14.
Displayed by

Next, a method of using the seismic intensity meter according to this embodiment will be explained.

First, place the seismic intensity meter at the observation location. In addition, conventional large seismic intensity meters use a spirit level to accurately determine the horizontal position and are fixed in a position that is exactly parallel to the horizon, but the seismic intensity meter according to this example is placed in a strictly horizontal position. do not have to,
This is a bandpass filter 24x, 24y, 24z
This is because components other than the earthquake frequency are cut.

In other words, the seismic intensity meter is tilted and the magnet 2 of the acceleration sensor 20
Even if 0"b is displaced, if it remains stationary, the component due to displacement is a DC component.
, 24y, and 24z. Therefore, the seismic intensity meter may be tilted as long as it remains stationary; for example, it may be hung on a wall instead of being placed horizontally.

Next, the power switch 12 turns on the power to the seismic intensity meter, the clear switch 16 clears the peak value held in the peak hold section 44, and the changeover switch 18 selects an instantaneous value.

Then, the magnitude R of the composite acceleration is calculated from the acceleration components in each direction detected by the acceleration sensors 20x, 203/, and 20z, and the seismic intensity at that time according to the value of R is determined by the comparator 40, and displayed on the display 14. will be displayed.

When an earthquake occurs, the instantaneous value of the seismic intensity is displayed moment by moment on the display unit 14 in accordance with the shaking of the earthquake. After the shaking subsides, change the changeover switch 18 to select the maximum value. Then, the peak value held in the peak hold section 44 is displayed on the display section 14, and the maximum seismic intensity of this earthquake can be known. Thereafter, the peak value held in the peak hold section 44 is cleared by the clear switch 16 in preparation for the next earthquake.

As described above, according to this embodiment, the seismic intensity can be extremely easily and accurately measured by placing the seismic intensity meter on a desk or hanging it on a wall.

A seismic intensity meter according to a second embodiment of the present invention will be explained using FIGS. 5 and 6. Components that are the same as those of the seismic intensity meter according to the first embodiment are given the same reference numerals and explanations will be omitted.

In this embodiment, not only the seismic intensity but also the direction of the epicenter is displayed. Assuming that the seismic intensity meter is placed almost horizontally in a predetermined direction, the acceleration sensors 20K and 2
The direction of the epicenter is calculated from the acceleration components in the X direction and the y direction due to 0y, and is displayed together with the magnitude of the composite acceleration.

That is, from the averaged signals X and Y averaged over a predetermined period by the averaging sections 36x and 36y, the calculation section 46 determines the direction of the resultant acceleration, that is, the epicenter, using the following equation θ=jan-'(Y/X). Find the angle θ indicating the direction of . Further, the calculation unit 48 calculates the magnitude P of the combined acceleration of the averaged signals X and Y using the following formula %.

Based on the angle θ and the magnitude P determined by the calculation units 46 and 48, the display unit 14 displays the direction of the epicenter and the magnitude of the earthquake as shown in Figure 6. As shown in , a concentric circle indicating a seismic intensity of 2.3.4.5.6 and a cross line indicating the north, south, east, and west directions are prepared in advance, and a display corresponding to the angle θ and the size P is displayed on this display section 14. , the display example in Figure 5 shows that an earthquake with a seismic intensity of 4 was detected with the epicenter in the northwest or southeast direction.

As described above, according to this embodiment, it is possible to know not only the seismic intensity but also the direction of the epicenter using a seismic intensity meter with a simple configuration.

The present invention is not limited to the above embodiments, and various modifications are possible.

For example, in the above embodiment, acceleration is converted into seismic intensity based on the seismic intensity table and displayed, but the acceleration value itself may be displayed.

Further, in the above embodiment, the composite acceleration is obtained from the acceleration components in three directions: the X direction, the y direction, and two directions, but the acceleration components in only two directions may be used as necessary.

Furthermore, although a barber pole type magnetoresistive element is used as the acceleration sensor in the above embodiment, other types of acceleration sensors such as a servo type acceleration sensor, a differential transformer type acceleration sensor, and a semiconductor acceleration sensor may be used.

[Effects of the Invention] As described above, according to the present invention, an inexpensive and compact seismic intensity meter that can easily measure seismic intensity of 11112 can be realized. Since it can be measured, ordinary households, schools, etc. can purchase it and measure the seismic intensity, allowing them to take prompt earthquake countermeasures. It can also be used as an auxiliary seismic intensity meter by specialized organizations such as the Japan Meteorological Agency. Furthermore, by arranging the seismic intensity meter of the present invention at a large number of points to reduce the seismic intensity to la, it is possible to more accurately identify the epicenter of an earthquake, and it can be useful for investigating signboards in a specific area.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing a seismic intensity meter according to the first embodiment of the present invention, Fig. 2 is a perspective view showing a magnetoresistive element type acceleration sensor used in the seismic intensity meter, and Fig. 3 is a perspective view showing the same magnetoresistive element type acceleration sensor. A block diagram of the acceleration sensor, Fig. 4 is a block diagram of the seismic intensity meter, Fig. 5 is a block diagram of the seismic intensity meter according to the second embodiment of the present invention, and Fig. 6 is an example of display of the seismic intensity meter in the direction of the epicenter. FIG. In the figure, 10... Housing 12... Power switch 14... Display section 16... Clear switch 18... Selector switch 20... Acceleration sensor 20a... Cantilever beam 20b... Magnets 20c, 20d... Magnetoresistive element 20e... Adder 2Of... Base 20g... Caps 20x, 20y, 20z... Acceleration sensor 22x,
22y, 22z...Amplifier 24x, 24y, 24z...Band pass filter 26x, 26y, 26z...Amplifier 28x, 28y, 28z--Absolute value section 30x, 30y
, 30 z - integration section 32x, 32y, 32z - A/D conversion section 34x, 34
y, 34z...Memories 36x, 36y, 36z-Averaging unit 38...Calculating unit 40...Comparing unit 42...Seismic intensity table 44...Peak hold unit 46...Calculating unit 48. ... Arithmetic unit jO-11 筐伜+2-一电缜? Good switch I4"-ta> receptacle 16 --- Clear switch + 8-11 F term switch 2C) =! --- Sword speed °C (Z direction) Perspective view showing the sensor Fig. 2 Block diagram of magnetic coffin Awago type 1-speed sensor Fig. 3 Fig. 6

Claims (1)

[Claims] 1. A plurality of acceleration sensors that detect acceleration in directions orthogonal to each other; and a plurality of bandpass filters that pass only frequency components that match the earthquake period in each acceleration signal of the plurality of acceleration sensors. and a plurality of averaging sections that average the respective acceleration signals that have passed through the plurality of bandpass filters, and calculating the magnitude of a composite acceleration obtained by combining the respective acceleration signals averaged by the plurality of averaging sections. an acceleration calculation unit; a seismic intensity table storing a relationship between the seismic intensity and acceleration of an earthquake; a seismic intensity determination unit that determines seismic intensity from the magnitude of the composite acceleration calculated by the calculation unit based on the seismic intensity table; A seismic intensity meter comprising: a display section that displays the seismic intensity determined by the seismic intensity determination section. 2. The seismic intensity meter according to claim 1, further comprising a direction calculation unit that calculates the direction of the composite acceleration based on each acceleration signal averaged by the plurality of averaging units, A seismic intensity meter characterized in that a direction is displayed on the display section as an epicenter direction.