A method and device for rapid and accurate location of earthquake sources at a single station

Abstract

The present application provides a method for rapid and precise location of earthquake sources at a single station, establishing a horizontal array variable of seismic pickups and a vertical array variable of seismic pickups, wherein the horizontal array variable of seismic pickups is a horizontal array; determining the angle value θ of the horizontal array seismic pickups, and determining preset parameters in combination with the geographical orientation, wherein the preset parameters include the average longitudinal wave velocity V p , average shear wave velocity V s ; The CPU edge interrupt function is used to collect the initial motion value of the seismic wave; the apparent incident angle of the seismic source is calculated according to the apparent incident angle formula; the true incident angle of the seismic source is calculated according to the true incident angle formula based on the apparent incident angle of the seismic source; the azimuth of the seismic source in the horizontal direction is calculated by the source azimuth formula for locating the source azimuth; the initial motion time difference is calculated by the initial motion time difference formula; the distance between the source and the station is calculated by the station distance formula; after the earthquake occurs, a single station collects high-quality longitudinal wave initial motions and quickly and accurately determines the source position.

Description

Technical Field

[0001] The invention belongs to the technical field of earthquake monitoring and single-chip computers, and in particular relates to a method and device for quickly and accurately locating an earthquake source at a single station. Background Art

[0002] Earthquake monitoring and location are often necessary in earthquake prevention and disaster reduction, military operations, and other activities. Traditional methods use multiple stations networked together to locate earthquake hypocenters, which often requires long calculation times and hinders rapid post-earthquake decision-making. Furthermore, the sparseness of the stations makes it impossible to perform joint calculations across multiple stations. A single station allows for rapid and flexible deployment. If a single station can quickly and accurately locate an earthquake hypocenter, it would significantly improve earthquake emergency response capabilities. In recent years, attempts have been made to locate an earthquake hypocenter using a single station, specifically by using a three-component seismic pickup to collect seismic data for calculation and location. However, because the sensitivity of the three-component geophone differs significantly from the hypocenter's azimuth, high-quality P-wave first-motion data is often not collected. This results in low calculation accuracy and large errors, limiting the application of single-station location. Therefore, a device for rapid and precise single-station source location is needed to ensure that the station receives high-quality P-wave first-motion data after an earthquake and quickly and accurately determines the hypocenter's location. Summary of the Invention

[0003] The present invention can make up for the shortcomings of low precision and large error in locating the earthquake source by using a single station at the current stage, and use multiple seismic pickups at a single station to quickly locate the earthquake source, thereby improving the speed and precision of locating the earthquake source at a single station. The data acquisition of the present invention is completed by a single-chip microcomputer responding to an interrupt of an analog-to-digital chip. The single-chip microcomputer can use commercially available chips such as the 51 series, or it can use a PLC and a DSP series to collect data. The present invention is not limited to this. The data calculation algorithm programming language can be implemented using C language, JAVA language, etc. This embodiment uses C language.

[0004] The purpose of this embodiment is to provide a method for quickly and accurately locating the earthquake source at a single station, which solves the problem that earthquake source calculation requires large-area deployment of sensors and has low calculation accuracy and large errors.

[0005] A method for rapid and precise location of earthquake sources at a single station, comprising:

[0006] Establishing a horizontal vibration pickup array variable and a vertical vibration pickup array variable, wherein the horizontal vibration pickup array variable is a horizontal array;

[0007] Determine the angle value of the horizontal vibration pickup θ, and determine the preset parameters in combination with the geographical orientation, wherein the preset parameters include the average longitudinal wave velocity V p , average shear wave velocity V s ;

[0008] The CPU edge interrupt function is used to collect the initial motion value of the seismic wave;

[0009] Calculate the apparent incident angle of the earthquake source according to the apparent incident angle formula;

[0010] Calculating the true incident angle of the seismic source using a true incident angle formula according to the apparent incident angle of the seismic source;

[0011] The horizontal azimuth of the earthquake source is calculated by the earthquake source azimuth formula to locate the earthquake source azimuth;

[0012] Calculate the initial movement time difference using the initial movement time difference formula;

[0013] Calculate the distance between the earthquake source and the station using the station distance formula;

[0014] The focal depth is calculated using the focal depth formula;

[0015] Generate report output.

[0016] Furthermore, the formula for the incident angle is in,

[0017] A j is the initial amplitude of the longitudinal wave of the j-th subscript horizontal vibration pickup,

[0018] A N is the initial amplitude of the longitudinal wave in the vertical direction of the vibration pickup,

[0019] γ 视 is the apparent incident angle.

[0020] Furthermore, the true angle of incidence formula is Among them, V p is the average longitudinal wave velocity,

[0021] V s is the average shear wave velocity,

[0022] γ 视 is the apparent incident angle,

[0023] γ 真 is the true angle of incidence.

[0024] Furthermore, the earthquake source orientation formula is α=j×θ+β, where

[0025] j: is the subscript number of the maximum initial amplitude of the horizontal array,

[0026] θ: is the θ angle,

[0027] β: is the deflection angle formula.

[0028] Furthermore, the deflection angle formula is in,

[0029] A u: is the amplitude value of the horizontal array of the u-th subscript,

[0030] A v : is the amplitude value of the horizontal array of the vth subscript,

[0031] θ: is the angle θ,

[0032] β: deflection angle.

[0033] Furthermore, the initial time difference formula is ΔT = TS-TP, where

[0034] TS: time of first movement of shear wave,

[0035] TP: Time of first movement of longitudinal wave,

[0036] ΔT: initial movement time difference.

[0037] Furthermore, the station distance formula is in,

[0038] D: distance between the earthquake source and the station,

[0039] V p : is the average longitudinal wave velocity,

[0040] V s : is the average velocity of the shear wave,

[0041] ΔT: is the initial movement time difference.

[0042] Furthermore, the formula for focal depth is: in,

[0043] H: focal depth,

[0044] V p : is the average longitudinal wave velocity,

[0045] V s : is the average velocity of the shear wave,

[0046] ΔT: is the initial time difference,

[0047] γ 真 : is the true incident angle of the earthquake source.

[0048] The present invention also provides a single-station earthquake source rapid and precise positioning device, comprising:

[0049] A base (1), a horizontal vibration pickup (2), and a vertical vibration pickup (3), characterized in that the horizontal vibration pickup (2) is installed at equal angles around the base (1), and the vertical vibration pickup (3) is installed at the center of the base (1).

[0050] Further,

[0051] The base (1) is divided into equal parts according to the angle θ with due north as the starting orientation.

[0052] The present invention provides a method and device for rapidly and accurately locating a seismic source at a single station. This method employs a circular surface composed of multiple sensors pointing to the center of a circle at equal angles, along with a vertical sensor in an inverted T-shaped configuration. Combined with a data acquisition algorithm, this method addresses the issues of earthquake source calculation, such as the need for widespread sensor deployment, low precision, and large errors. After an earthquake occurs, a single station can collect high-quality P-wave first motions and quickly and accurately determine the seismic source.

[0053] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 : A step diagram of the method for rapid and accurate location of earthquake sources at a single station provided in an embodiment of the present application;

[0055] Figure 2 : A side view of the device for rapid and precise location of earthquake sources at a single station provided in an embodiment of the present application;

[0056] Figure 3 : A top view of the device for rapid and precise location of earthquake sources at a single station provided in an embodiment of the present application;

[0057] Figure 4 : A waveform diagram of the seismic wave initial motion value sampling of the method for rapid and accurate earthquake source positioning at a single station provided in an embodiment of the present application; DETAILED DESCRIPTION

[0058] The present invention can make up for the shortcomings of low precision and large error in locating the earthquake source by using a single station at the current stage, and use multiple seismic pickups at a single station to quickly locate the earthquake source, thereby improving the speed and precision of single-station earthquake source positioning. The data acquisition of the present invention is completed by a single-chip microcomputer responding to the interruption of the analog-to-digital chip. The vibration data acquisition single-chip microcomputer can use any commercial chip such as the 51 series, and the analog-to-digital chip has a bit number of 10-32 bits. PLC and DSP series can also be used to collect data. The present invention is not limited to this. The data calculation algorithm programming language can be implemented using C language, JAVA language, etc. This embodiment uses C language.

[0059] The following will describe the technical solutions in the embodiments of the present application in conjunction with the accompanying drawings. Figure 1 , see the device diagram Figure 2 .

[0060] S1100: Establish a horizontal direction vibration pickup data receiving array, marked as horizontal direction array, the array subscript corresponds to N horizontal direction vibration pickups (2) one by one, establish a vertical direction (3) vibration pickup variable, store the vertical direction initial movement value, marked as vertical direction variable, the initial movement value sampling uses the edge interrupt reading method, see Figure 4 , collect data by edge-triggered CPU interrupt function. Enter step S1200.

[0061] S1200: Determine the angle θ according to the formula θ=360 / N. Place a vibration pickup at every θ angle in the horizontal circumference. The θ angle is generally between 10° and 15°. In this embodiment, the θ angle is 10°. A total of 36 vibration pickups are placed horizontally, marked as N=36. Determine the average longitudinal wave velocity V according to the azimuth of the area where the present invention is located. p , the speed is between 5.5 and 7 km / s, and in this embodiment, the value is 5.92 km / s, and the average shear wave speed V is determined s , the speed range is 3.2 to 4.0 km / s, and the value of this embodiment is 3.46 km / s. The N vibration pickups are numbered in the horizontal array in a clockwise order as array subscripts, which are 0, 1, 2, 3, 4, ..., i, ..., N-1. Each subscript corresponds to an azimuth angle. The i-th azimuth angle αi = i × θ, and the process goes to step S1300.

[0062] S1300: When an earthquake occurs, the CPU edge interrupt function collects and reads the initial longitudinal wave motion values ​​of each horizontal vibration pickup (2) and vertical vibration pickup (3) and places them into the corresponding horizontal array and vertical variable. The data stored in the horizontal array is divided into two types: positive jump value and reverse jump value. The marking method is that the positive jump is marked with "+" and the reverse jump is marked with "-". The positive jump here is when the vibration pickup (2) moves upward from the static state relative to the ground surface. On the contrary, when the vibration pickup (2) moves from the static state toward the ground surface, it is a reverse jump, and the process enters step S1400.

[0063] S1400: Calculate the apparent incident angle of the earthquake source according to the apparent incident angle formula. The formula is:

[0064]

[0065] Among them, A j is the initial amplitude of the longitudinal wave of the j-th subscript horizontal vibration pickup (2), that is, the amplitude data of the j-th subscript of the horizontal array, A N The initial amplitude of the longitudinal wave of the vertical vibration pickup (3), that is, the data in the vertical variable, enters step S1500.

[0066] S1500: Calculate the true incident angle of the earthquake source based on the apparent incident angle of the earthquake source. The formula is: Among them, V p is the average longitudinal wave velocity, V s is the average shear wave velocity, γ 视 is the apparent incident angle of the earthquake source, γ 真 is the true incident angle of the earthquake source, and the process goes to step S1600.

[0067] S1600: Calculate the horizontal azimuth of the earthquake source for locating the earthquake source. The formula for calculating the horizontal azimuth of the earthquake source is α = j × θ + β, where:

[0068] j is the array index number of the horizontal array with the maximum initial motion amplitude and a positive initial motion value. Based on j, the two adjacent array indexes of j are obtained and recorded as u and v.

[0069] The array subscript relationship of j, u, and v is:

[0070] u is the remainder of N+j+1 over N, i.e. u=mod(N+j+1,N);

[0071] v is the remainder of N+j-1 with respect to N, i.e. v=mod(N+j-1,N);

[0072] In the formula

[0073] in,

[0074] A u is the initial amplitude of the longitudinal wave of the u-th subscript horizontal vibration pickup (2), that is, the amplitude data of the u-th subscript of the horizontal array;

[0075] A v is the initial amplitude of the longitudinal wave of the v-th subscript horizontal vibration pickup (2), that is, the amplitude data of the v-th subscript of the horizontal array;

[0076] Go to step S1700.

[0077] S1700: Calculate the longitudinal wave initial movement time TP and the transverse wave initial movement time TS by the clock cycle counting method of the microprocessor, and calculate the initial movement time difference according to the formula, the formula is ΔT=TS-TP, where ΔT is the initial movement time difference, and enter step S1800.

[0078] S1800: Based on the average longitudinal wave velocity V p and the mean shear wave velocity V s Calculate the distance between the earthquake source and the station using the following formula:

[0079] Where D is the distance between the earthquake source and the station, V p : average longitudinal wave velocity, V s: average velocity of shear waves, ΔT is the initial motion time difference, and the process goes to step S1900.

[0080] S1900: Based on the results of step S1600, step S1800, and step S1500, the focal depth is calculated using the formula: Where H is the focal depth, V p is the average longitudinal wave velocity, V s is the average velocity of shear waves, ΔT is the time difference of initial motion, γ 真 is the true incident angle of the seismic source, and the process goes to step S2000.

[0081] S2000: Generate a report output based on the results of calculating the horizontal azimuth of the earthquake source, the distance of the earthquake source from the station, and the depth of the earthquake source relative to the surface according to the steps of this embodiment.

[0082] The present invention also provides a device corresponding to the above steps, see Figure 2 A single-station earthquake source rapid and precise positioning device comprises a foundation (1), a horizontal vibration pickup (2), a vertical vibration pickup (3),

[0083] The horizontal vibration pickups (2) are installed at equal angles around the foundation (1). The foundation (1) is a cylindrical concrete pile body, vertically embedded in the bedrock, and has a diameter of 2.0m to 3.0m. The vertical vibration pickup (3) is installed at the center of the foundation (1). The horizontal vibration pickup (2) is installed horizontally with its maximum sensitivity direction facing the center of the foundation (1).

[0084] The base (1) is divided into equal parts according to the angle θ, starting from the true north. The value of θ is determined according to the positioning accuracy and is 10° to 15°. In this embodiment, 10° is used.

[0085] The horizontal vibration pickup (2) and the vertical vibration pickup (3) use sensors with the same performance indicators. The difference between them is that the horizontal vibration pickup is installed horizontally, and its maximum sensitive direction points to the center of the foundation (1), while the vertical vibration pickup is installed vertically, and its maximum sensitive direction always points to the ground surface, so as to achieve accurate positioning of the incident angle of the earthquake source.

[0086] When the seismic wave propagates from the outside of the foundation (1) to the inside of the foundation (1), the seismic pickup (2) jumps in the positive direction. When the wave propagates from the inside of the foundation (1) to the outside of the foundation (1), the seismic pickup (2) jumps in the negative direction. The purpose is that no matter where the earthquake source is at the station, there is always a maximum sensitive direction of the corresponding horizontal seismic pickup (2) with an angle of no more than 0.5θ with the earthquake source azimuth, thereby achieving accurate positioning of the earthquake source azimuth.

[0087] The selection of performance parameters of the horizontal vibration pickup (2) and the vertical vibration pickup (3) requires consistency testing, and the difference in consistency amplitude of each vibration pickup is no more than 2%.

[0088] The present invention deploys multiple sensors pointing to the center of the circle at equal angles to form a circular surface, and a vertical sensor forms an inverted T-shaped structure. Combined with a data acquisition algorithm, this solves the problem of earthquake source calculation requiring large-scale sensor deployment, resulting in low calculation accuracy and large errors. After an earthquake occurs, a single station can collect high-quality P-wave first motions and quickly and accurately determine the earthquake source location.

[0089] The foregoing is merely an embodiment of the present application and is not intended to limit the scope of protection of the present application. For those skilled in the art, various modifications and variations of the present application are possible. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A method for rapid and accurate location of earthquake sources at a single station, characterized in that: include: Establishing a horizontal vibration pickup array variable and a vertical vibration pickup array variable, wherein the horizontal vibration pickup array variable is a horizontal array; Determine the angle value of the horizontal vibration pickup θ, including deploying multiple sensors pointing to the center of the circle at equal angles to form a circular surface and a vertical sensor to form an inverted T-shaped structure, and determine the preset parameters in combination with the geographical orientation, wherein the preset parameters include the average longitudinal wave velocity V p , average shear wave velocity V s ; The CPU edge interrupt function is used to collect the initial motion value of the seismic wave; Calculate the apparent incident angle of the earthquake source according to the apparent incident angle formula; Calculating the true incident angle of the seismic source using a true incident angle formula according to the apparent incident angle of the seismic source; The horizontal azimuth of the earthquake source is calculated by the earthquake source azimuth formula to locate the earthquake source azimuth; the earthquake source azimuth formula is α=j×θ+β, where j is the subscript number of the maximum initial amplitude of the horizontal array, θ is the θ angle, and β is the deflection angle formula; the deflection angle formula is in, A u : is the amplitude value of the horizontal array of the u-th subscript, A v : is the amplitude value of the horizontal array of the vth subscript, θ: is the θ angle, β: is the deflection angle; Calculate the initial movement time difference using the initial movement time difference formula; Calculate the distance between the earthquake source and the station using the station distance formula; The focal depth is calculated using the focal depth formula; Generate report output.

2. The method for rapid and precise location of earthquake sources at a single station according to claim 1, characterized in that: The formula for the apparent incident angle is: in, A j is the initial amplitude of the longitudinal wave of the j-th subscript horizontal vibration pickup, A N is the initial amplitude of the longitudinal wave in the vertical direction of the vibration pickup, γ 视 is the apparent incident angle.

3. The method for rapid and precise location of earthquake sources at a single station according to claim 1 or 2, characterized in that: The true angle of incidence formula is in, V p is the average longitudinal wave velocity, V s is the average shear wave velocity, γ 视 is the apparent incident angle, γ 真 is the true angle of incidence.

4. The method for rapid and precise location of earthquake sources at a single station according to claim 1, characterized in that: The initial time difference formula is ΔT=TS-TP, where: TS: time of first movement of shear wave, TP: Time of first movement of longitudinal wave, ΔT: initial movement time difference.

5. The method for rapid and precise location of earthquake sources at a single station according to claim 1 or 4, characterized in that: The station distance formula is in, D: distance between the earthquake source and the station, V p : is the average longitudinal wave velocity, V s : is the average velocity of the shear wave, ΔT: is the initial movement time difference.

6. The method for rapid and precise location of earthquake sources at a single station according to claim 1, characterized in that: The focal depth formula is: Among them, H is the focal depth, V p : is the average longitudinal wave velocity, V s : is the average velocity of the shear wave, ΔT: is the initial motion time difference, γ 真 : is the true incident angle of the earthquake source.

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