A method for synthesizing acceleration waveforms of destructive earthquakes at fixed stations

Abstract

The purpose of the present invention is to provide a method for synthesizing the acceleration waveform of a destructive earthquake at a fixed station. The method relies on the empirical Green's function method, firstly obtains a relatively accurate source model and source parameters by synthesizing the acceleration time history of a strong motion instrument, and then uses the obtained source model and source parameters in the simulation of the large earthquake acceleration waveform at a broadband seismograph, and uses the small earthquake waveform recorded by the broadband seismograph as the Green's function to synthesize the large earthquake acceleration waveform at the broadband seismograph.

Description

Technical Field

[0001] The present application relates to a method for synthesizing a destructive earthquake acceleration waveform of a fixed station, which is applicable to the technical field of earthquake resistance services or post-earthquake emergency rescue. Background Art

[0002] During earthquakes, the damage and collapse of engineering structures are primarily caused by strong ground motion, which also serves as an external condition for other disasters such as foundation failure and landslides. The empirical Green's function method is an existing achievement and theory that can be used as a numerical simulation tool. It uses Green's functions, typically obtained from publicly available earthquake databases, to synthesize large earthquake ground motions. The source of a large earthquake is considered to be composed of a series of sub-seismic sources. An appropriately sized aftershock or foreshock record is selected as the Green's function, and small earthquakes are equated with sub-seismic sources. These empirical Green's functions are then superimposed according to a specific rupture pattern to produce the large earthquake ground motion time history.

[0003] The ground motion input of destructive earthquakes is very important for the seismic design and damage response analysis of major projects. In sparsely populated areas, such as the western region, earthquake monitoring capabilities are relatively weak. This is because seismic stations are mainly distributed in the relatively densely populated eastern region, and the main stations deployed in these areas are fixed stations with broadband seismometers. These fixed stations have high deployment requirements and are permanent stations. Although the number of such stations in the western region is much smaller than that in the eastern region, they still dominate the number of seismic stations in the western region. Earthquake early warning networks are generally built in densely populated areas, and are still very sparse in sparsely populated areas.

[0004] Broadband seismographs continuously record waveforms, even when no earthquake is occurring. They also record signals such as background noise. Their characteristic is a relatively narrow range for recording peak acceleration (PGA). This often results in clipping of data outside the range during destructive earthquakes or those with large amplitudes.

[0005] A strong motion instrument is an automatically triggered seismograph that records near-ground motion during strong earthquakes. It typically only begins recording acceleration waveforms during larger earthquakes. Furthermore, the instrument has a wide range of peak acceleration, typically exceeding ±2.0g, allowing it to record acceleration waveforms from all destructive earthquakes.

[0006] In the existing technology, earthquake monitoring is usually carried out mainly with broadband seismographs and supplemented by strong motion motion meters. For example, my country has two major seismic networks, namely the fixed network and the earthquake early warning network. Among them, all the fixed networks are broadband seismographs, and some stations in the earthquake early warning network are broadband seismographs. The number of these two networks deployed in the western region is relatively small, and the vast majority of the stations are broadband seismographs. Once an earthquake occurs, only a few strong motion motion meters will record the complete acceleration waveform of the large earthquake. Therefore, in the western region of my country, there are a large number of broadband seismographs but they cannot record the waveform of a large earthquake; there are fewer strong motion motion meters but they can fully record the waveform of a large earthquake. Summary of the Invention

[0007] The purpose of the present invention is to provide a method for synthesizing the acceleration waveform of a destructive earthquake at a fixed station. The method relies on the empirical Green's function method, firstly obtains a relatively accurate source model and source parameters by synthesizing the acceleration time history of a strong motion instrument, and then uses the obtained source model and source parameters in the simulation of the large earthquake acceleration waveform at a broadband seismograph, and uses the small earthquake waveform recorded by the broadband seismograph as the Green's function to synthesize the large earthquake acceleration waveform at the broadband seismograph.

[0008] The present application relates to a method for synthesizing a destructive earthquake acceleration waveform at a fixed station, comprising the following steps:

[0009] (1) After an earthquake occurs, determine the location of the broadband fixed station to be calculated based on actual needs; select the location of the strong earthquake station that is closest to the epicenter and has complete data;

[0010] (2) Collect and summarize the required earthquake source parameters based on the locations of the selected broadband fixed stations and strong motion stations;

[0011] (3) Perform different permutations and combinations on the source parameters to obtain a permutation and combination scheme of the source parameters;

[0012] (4) Determine the small earthquakes that can be used as Green's functions at the strong earthquake stations, determine the permutation and combination scheme of the small earthquakes according to the number and position of the asperities, and then further perform the permutation and combination of the small earthquakes and the source parameters with the permutation and combination scheme obtained;

[0013] (5) Using the empirical Green's function method, the acceleration waveform of the strong earthquake station is calculated for each permutation and combination obtained in the above steps, and the acceleration calculation results of all permutations and combinations are obtained;

[0014] (6) Based on the characteristics of the acceleration waveforms of the three components of this earthquake recorded by the strong earthquake station, the calculation results obtained in step (5) are screened;

[0015] (7) According to the calculation results after screening in step (6), all the results are counted, the frequency of occurrence of each source parameter is reversed, and the source parameter with the highest occurrence frequency is selected as the reliable parameter;

[0016] (8) Selecting small earthquakes at broadband fixed stations as Green's functions, determining the permutation and combination of small earthquakes at broadband fixed stations to be used based on the number and position of asperities, and applying the reliable parameters obtained in step (7) to the calculation of the acceleration waveforms of broadband fixed stations using the empirical Green's function method to obtain all possible acceleration results of broadband fixed stations;

[0017] (9) The results of step (8) are screened according to the seismic motion characteristics of the three components of the strong earthquake station and the attenuation relationship of the local area to obtain the final reliable acceleration waveform of the broadband fixed station.

[0018] Among them, the waveform segment intercepted by the small earthquake is the waveform data 40 seconds after the initial motion of the P wave as the available waveform segment; the selected small earthquakes have the following characteristics: the distance between the epicenter of the small earthquake and the epicenter of the main shock does not exceed 500m; when each asperity is selected for a small earthquake, the condition to be met is that the distance between the epicenter of the small earthquake and the initial rupture position of each asperity does not exceed 500m; the error between the focal depth of the small earthquake selected for each asperity and the initial rupture position of each asperity does not exceed 500m.

[0019] Among them, in step (6), the screening criteria are: select the three strong earthquake stations closest to the epicenter, and the epicenter distance of the strong earthquake station should be within 200 km; obtain the average value of the PGA of the three-component acceleration waveforms of the three strong earthquake stations, and calculate the ratio of the EW / NS component, the ratio of the NS / EW component, the ratio of the EW / UD component, the ratio of the UD / EW component, the ratio of the NS / UD component, and the ratio of the UD / NS component of each strong earthquake station;

[0020] Take the average value of the six ratios of the three strong earthquake stations, and then we will obtain the value ranges of EW / NS and NS / EW, the value ranges of EW / UD and UD / EW, and the value ranges of NS / UD and UD / NS; so that the PGA of the three components of all simulation values ​​should be within the above three ranges respectively, and the waveform that conforms to the three value ranges is used as the final simulation result of the strong earthquake acceleration waveform of the broadband fixed station.

[0021] Preferably, the range of the envelope of all response spectra that meet the requirements is used as the value range of the response spectrum of the MAD station; the maximum and minimum values ​​of the PGA of each component of all results are used as the value range of the PGA of each component of the MAD station; and finally, the acceleration waveform, the range of the acceleration response spectrum and the value range of the PGA that meet the requirements of the MAD station are obtained.

[0022] This application uses an indirect method to synthesize the acceleration waveform of a broadband seismograph, which can provide excellent data support for post-earthquake emergency rescue, seismic design of local projects, ground motion input, and local earthquake disaster prevention and mitigation planning. This application can provide more accurate acceleration waveforms of large earthquakes in areas lacking strong earthquake stations, helping to obtain more accurate earthquake damage response analysis results, thereby serving earthquake resistance design and earthquake disaster prevention efforts. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a comparison chart of the observed and simulated values ​​of the acceleration waveform of a certain station.

[0024] Figure 2 It is a comparison chart of the simulated average value and the observed value of the response spectrum of the acceleration waveform of a certain station. DETAILED DESCRIPTION

[0025] To make the purpose, technical solutions and advantages of this application more clear, the embodiments of this application will be described in detail below with reference to the accompanying drawings. It should be noted that, unless there is a conflict, the embodiments and features in the embodiments of this application can be combined with each other in any way.

[0026] The present application relates to a method for synthesizing a destructive earthquake acceleration waveform at a fixed station, comprising the following steps:

[0027] (1) After an earthquake occurs, determine the location of the broadband fixed station to be calculated based on actual needs; select the location of the strong earthquake station that is closest to the epicenter and has complete data;

[0028] (2) Collect and summarize the required earthquake source parameters based on the locations of the selected broadband fixed stations and strong motion stations;

[0029] (3) Perform different permutations and combinations on the source parameters to obtain a permutation and combination scheme of the source parameters;

[0030] (4) Determine the small earthquakes that can be used as Green's functions at the strong earthquake stations, determine the permutation and combination scheme of the small earthquakes according to the number and position of the asperities, and then further perform the permutation and combination of the small earthquakes and the source parameters with the permutation and combination scheme obtained;

[0031] (5) Using the empirical Green's function method, the acceleration waveform of the strong earthquake station is calculated for each permutation and combination obtained in the above steps, and the acceleration calculation results of all permutations and combinations are obtained;

[0032] (6) Based on the characteristics of the acceleration waveforms of the three components of this earthquake recorded by the strong earthquake station, the calculation results obtained in step (5) are screened and the results that do not meet the requirements are eliminated;

[0033] (7) According to the calculation results after screening in step (6), all the results are counted, the frequency of occurrence of each source parameter is reversed, and the source parameter with the highest occurrence frequency is selected as the reliable parameter;

[0034] (8) Selecting small earthquakes at broadband fixed stations as Green's functions, determining the permutation and combination of small earthquakes at broadband fixed stations to be used based on the number and position of asperities, and applying the reliable parameters obtained in step (7) to the calculation of the acceleration waveforms of broadband fixed stations using the empirical Green's function method to obtain all possible acceleration results of broadband fixed stations;

[0035] (9) The results of step (8) are screened based on the seismic motion characteristics of the three components of the strong earthquake station and the attenuation relationship of the local area to obtain the final reliable acceleration waveform of the broadband fixed station. This result can be represented by several acceleration waveforms and the value range of the PGA of these waveforms.

[0036] The method for synthesizing destructive earthquake acceleration waveforms at fixed stations involved in this application is actually based on the actual small earthquake waveform as the Green's function to synthesize the ground motion to obtain a relatively accurate acceleration waveform. The specific steps are as follows:

[0037] (1) After a destructive earthquake occurs, the magnitude and epicenter of the earthquake are determined based on the measurements of the seismic network. Based on the epicenter, waveform information is obtained from several strong-motion earthquake stations with strong-motion earthquake instruments installed closest to the epicenter. The stations with complete waveforms are selected as reference stations. The distance from the epicenter of a strong-motion earthquake station should not exceed 200 km. This step is mainly to select appropriate strong-motion earthquake stations for the next step. If the waveform does not show any truncation from the beginning to the end of the earthquake, it can be considered to meet the waveform integrity requirement.

[0038] (2) Determine source parameters

[0039] Source parameters that need to be determined include the mainshock's focal mechanism, focal depth, focal rise time, number of subfaults on the mainshock's fault plane, shear wave velocity and rupture velocity, initial rupture location, station azimuth and epicentral distance, number and location of asperities, and the ratio of stress drops between large and small earthquakes. These parameters can be obtained from public sources. The number of subfaults and the number and location of asperities on the mainshock's fault plane are determined by the dislocation distribution model on the mainshock's fault rupture surface. Asperities are defined by Somerville et al. (1999) as areas of relatively large slip dislocation on the fault rupture surface. Simplified asperity models are estimated based on inversion results from different researchers. These models typically use squares of varying numbers and positions to characterize their spatial location. Different simplified models may vary in size, position, and number, but these remain within acceptable limits.

[0040] After an earthquake occurs, many scientific research institutions, business departments, and scientific researchers will provide the calculation results of the above-mentioned source parameters. Considering various uncertainties, each source parameter should select at least three reliable source parameters from these calculation results, and then arrange and combine all the parameters. Finally, N all The corresponding source model parameters are input into the program to obtain N all The results of the earthquake simulation.

[0041] (3) Permutations and combinations of options

[0042] Small earthquake data can be requested from the National Strong Motion Network Center or the China Earthquake Networks Center. The epicenter of a small earthquake should be located at the re-precise longitude and latitude. The magnitude of the selected small earthquake can range from 3 to 5. This method uses the acceleration waveform of a small earthquake as the Green's function to synthesize a large earthquake. Therefore, the waveform segment captured from the small earthquake generally consists of the 40 seconds after the onset of the P wave.

[0043] If the mainshock has multiple asperities, the earthquake rupture process determines the initial rupture location on each asperity, starting from the initial rupture point and propagating to each asperity. Within each asperity, a small earthquake within 500 meters of the initial rupture point is selected as the Green's function. This means that a different small earthquake is selected as the Green's function for each asperity. There may be more than one small earthquake within each asperity that meets these criteria, and all such small earthquakes should be used as the Green's function for their respective asperities. The selected small earthquakes must also meet the following requirements: their precisely located epicenter should be no more than 500 meters from the mainshock's epicenter. Furthermore, the selection of small earthquakes for each asperity must ensure that their epicenter is close to the initial rupture location of the respective asperity, with a maximum error of 500 meters. The focal depth of the small earthquake selected for each asperity should be close to the initial rupture location of each asperity, with an error of no more than 500 meters. After obtaining the appropriate small earthquake on each asperity, all the source parameters in the above steps are fully arranged and combined to obtain all possible arrangements and combinations.

[0044] The input part of the calculation process consists of two parts. One part is the parameter part. As mentioned above, there will be N all The second part is the selection of small earthquakes, that is, the number of small earthquakes that meet the requirements for each concave-convex body. The combination content of this link is mainly the number of concave-convex bodies and the number of small earthquakes for each concave-convex body. Assume that there are i (i≤3) concave-convex bodies, and the number of small earthquakes for each concave-convex body is M i (i=1, 2, 3), there are M combinations of small earthquakes. When i=1, there are M=M1 combinations of small earthquakes; when i=2, there are M=M1*M2 combinations of small earthquakes; when i=3, there are M=M1*M2*M3 combinations of small earthquakes. The final total number of parameters and combinations of small earthquakes is N all *M. N all *M combinations are sequentially input into the empirical Green function method as Green functions, and finally N all *M results.

[0045] (4) The screening process of simulation results.

[0046] The acceleration waveform of a strong earthquake at a strong earthquake station is certain. all *The results of M acceleration waveforms must be compared and analyzed with the observed waveforms, and results with large differences must be eliminated. The elimination criteria can be as follows:

[0047] Three points of PGA should be in PGA obs 0.8-1.2 times, PGA obs Indicates the PGA value of the observation value. The three components are EW component, NS component, and UD component.

[0048] The waveform of the simulated value should be similar to that of the observed value. This step can be screened by referring to the 90% energy duration parameters of the simulated value and the observed value. The 90% energy duration of the simulated value should also be within the range of 0.8-1.2 times the 90% energy duration of the observed value. Figure 1 As shown in the figure, a comparison chart of the observed and simulated values ​​of the acceleration waveform of a certain station is shown, with the upper part showing the observed value and the lower part showing the simulated value.

[0049] The waveform of the simulated value should also be similar to the acceleration response spectrum of the observed value. Figure 2 As shown in , the average value of the response spectrum of all simulated acceleration waveforms should be very close to the acceleration response spectrum of the observed value. If the average value is far away from the acceleration response spectrum of the observed value, it is necessary to continuously delete the simulated values ​​to make the average value of the simulated acceleration response spectrum closer to the observed value response spectrum. The standard for closeness can be that the observed value acceleration response spectrum and the average value response spectrum of the simulated value have at least 3 intersections from left to right, such as Figure 2 The final acceleration simulation value that meets the above three screening conditions is the final acceleration simulation value that meets the requirements.

[0050] (5) After obtaining a certain number of acceleration results in step (4), the statistical results of the source parameters of all simulated acceleration waveforms are calculated. That is, for each parameter corresponding to the simulated acceleration waveform, the value with the highest frequency of occurrence is selected as the parameter with higher accuracy. The value with the highest total frequency of occurrence of all parameters will be used in the subsequent calculation of the simulated broadband fixed station acceleration waveform.

[0051] (6) After obtaining relatively accurate source parameters of the large earthquake, we begin to calculate the acceleration waveform of the large earthquake at the broadband fixed station. The acceleration waveforms of all small earthquakes at the broadband fixed station can be obtained from the station network database. The waveform segment of the small earthquake is generally the waveform data of 40 seconds after the onset of the P wave as the available waveform segment.

[0052] First, basic information on magnitude 3-5 aftershocks of the major earthquake is obtained from the network database. The epicenter of the aftershock is selected from the new longitude and latitude of the aftershock precision positioning. The distance between the new epicenter of the small earthquake and the epicenter of the main shock is no more than 500m. The steps and criteria for selecting small earthquakes for each asperity are the same as those for selecting small earthquakes at the strong earthquake station in step (3).

[0053] (7) The M combinations of small earthquakes obtained in step (6) and the source parameters obtained in steps (4) and (5) are sequentially input into the empirical Green's function method, and finally the M three-component broadband fixed station acceleration waveform simulation results are obtained. The M simulated broadband seismograph acceleration waveform results are further screened.

[0054] The screening criteria are as follows: Select the three strong earthquake stations closest to the epicenter, and the distance between the strong earthquake stations and the epicenter should be within 200km. Obtain the average value of the PGA of the three-component acceleration waveforms of the three strong earthquake stations, such as the three closest strong earthquake stations within 200km. Calculate the ratio of the EW / NS component, the ratio of the NS / EW component, the ratio of the EW / UD component, the ratio of the UD / EW component, the ratio of the NS / UD component, and the ratio of the UD / NS component of each strong earthquake station. Take the average value of the six ratios of the three strong earthquake stations, and then you will get three value ranges, such as the value range of EW / NS and NS / EW, the value range of EW / UD and UD / EW, and the value range of NS / UD and UD / NS. The PGA of the M types of broadband seismographs obtained in this step should comply with the above three value ranges, that is, the PGA of the three components of all simulated values ​​should be within the above three ranges respectively. Only waveforms that meet the three value ranges at the same time can be used as the final simulation results of the large earthquake acceleration waveform of the broadband fixed station (MAD).

[0055] The range of the envelope of all response spectra that meet the requirements is used as the value range of the response spectrum of the MAD station. The maximum and minimum values ​​of the PGA of each component of all results are used as the value range of the PGA of each component of the MAD station. Finally, the acceleration waveform, the range of the acceleration response spectrum, and the value range of the PGA that meet the requirements of the MAD station are obtained. The above three angles can comprehensively characterize the comprehensive seismic motion characteristics of this major earthquake at the wide-band fixed station. The acceleration waveform of the major earthquake obtained through this step is considered to be close to the acceleration waveform of the actual major earthquake at the station, and can be used for earthquake disaster prevention and reduction applications such as seismic input for local building seismic design.

[0056] Although the embodiments disclosed in this application are as described above, the contents described are merely embodiments adopted to facilitate understanding of this application and are not intended to limit this application. Any person skilled in the art of the art to which this application belongs may make any modifications and changes in the form and details of the implementation without departing from the spirit and scope disclosed in this application. However, the scope of patent protection of this application shall still be based on the scope defined by the attached claims.

Claims

1. A method for synthesizing destructive earthquake acceleration waveforms at fixed stations, characterized in that: The following steps are involved: (1) After a destructive earthquake occurs, the magnitude and epicenter of the earthquake are obtained based on the measurement results of the seismic network; Determine the location of the broadband fixed stations to be calculated based on actual needs; select the location of the strong motion station closest to the epicenter of the earthquake with complete data; obtain waveform information from several strong motion stations with strong motion instruments closest to the epicenter based on the epicenter location, and select the strong motion station with complete waveforms as the reference station. The distance between the strong motion stations and the epicenter should not exceed 200 km. (2) Based on the locations of the selected broadband fixed stations and strong earthquake stations, collect and summarize the required source parameters; the source parameters that need to be determined include the focal mechanism of the main shock, the focal depth, the focal rise time of the main shock, the number of sub-faults on the main shock fault plane, the shear wave velocity and rupture velocity, the initial rupture position of the earthquake, the azimuth and epicentral distance of the station, the number and location of asperities, and the ratio of stress drops of large and small earthquakes; (3) Perform different permutations and combinations on the source parameters to obtain a permutation and combination scheme of the source parameters; after the earthquake occurs, according to the calculation results of the above-mentioned source parameters given by scientific research units, business departments, and scientific researchers, considering various uncertainties, each source parameter selects at least three reliable source parameters from the calculation results of the above-mentioned source parameters, and then permutations and combinations are performed on all the parameters, and finally N source parameters will be obtained. all Types of source model parameters, input into the program will get N all The results of earthquake simulation; (4) Determine the small earthquakes that can be used as Green's functions at the strong earthquake station. The epicenter of the small earthquake is selected from the longitude and latitude after re-precision positioning. The magnitude range of the selected small earthquakes is 3-5. Determine the permutation and combination scheme of the small earthquakes according to the number and position of the asperities, and then further permutate and combine the small earthquakes and the source parameters with the permutation and combination scheme of the obtained source parameters. Among them, each asperity will select a different small earthquake as the Green's function. All small earthquakes that meet the conditions are used as the Green's function of their respective asperities. The selected small earthquakes have the following characteristics: the epicenter of the small earthquake after precise positioning is no more than 500m away from the epicenter of the main earthquake. At the same time, when selecting small earthquakes, the epicenter of each asperity should be no more than 500m away from the initial rupture position of each asperity; the focal depth of the small earthquake selected for each asperity should be close to the initial rupture position of each asperity, with an error of no more than 500m. (5) Use the empirical Green's function method to calculate the acceleration waveform of the strong earthquake station for each permutation and combination obtained in the above steps, and obtain the acceleration calculation results of all permutations and combinations; the input part of the calculation process consists of two parts, one is the parameter part, there will be N all The second part is the number of small earthquakes that meet the requirements for each concave-convex body. The combination content of this link is mainly the number of concave-convex bodies and the number of small earthquakes for each concave-convex body. There are M combinations of small earthquakes; N all *M combinations are sequentially input into the empirical Green function method as Green functions, and finally N all *M kinds of results; (6) Based on the characteristics of the acceleration waveforms of the three components of this earthquake recorded by the strong earthquake station, the calculation results obtained in step (5) are screened; (7) According to the calculation results after screening in step (6), all the results are counted, the frequency of occurrence of each source parameter is reversed, and the source parameter with the highest occurrence frequency is selected as the reliable parameter; (8) Selecting small earthquakes at broadband fixed stations as Green's functions, determining the permutation and combination of small earthquakes at broadband fixed stations to be used based on the number and position of asperities, and applying the reliable parameters obtained in step (7) to the calculation of the acceleration waveforms of broadband fixed stations using the empirical Green's function method to obtain all possible acceleration results of broadband fixed stations; (9) The results of step (8) are screened according to the seismic motion characteristics of the three components of the strong earthquake station and the attenuation relationship of the local area to obtain the final reliable acceleration waveform of the broadband fixed station.

2. The method for synthesizing destructive earthquake acceleration waveforms at fixed stations according to claim 1, characterized in that: The waveform segment intercepted by the small earthquake is the waveform data 40 seconds after the initial movement of the P wave as the available waveform segment.

3. The method for synthesizing destructive earthquake acceleration waveforms at fixed stations according to any one of claims 1 to 2, characterized in that: In step (6), the screening criteria are as follows: select the three strong earthquake stations closest to the epicenter, obtain the average value of the PGA of the three-component acceleration waveforms of the three strong earthquake stations, and calculate the ratio of the EW / NS component, the ratio of the NS / EW component, the ratio of the EW / UD component, the ratio of the UD / EW component, the ratio of the NS / UD component, and the ratio of the UD / NS component of each strong earthquake station; Take the average value of the six ratios of the three strong earthquake stations, and then we will obtain the value ranges of EW / NS and NS / EW, the value ranges of EW / UD and UD / EW, and the value ranges of NS / UD and UD / NS; so that the PGA of the three components of all simulation values ​​should be within the above three ranges respectively, and the waveform that conforms to the three value ranges is used as the final simulation result of the strong earthquake acceleration waveform of the broadband fixed station.

4. The method for synthesizing the destructive earthquake acceleration waveform of a fixed station according to claim 3, characterized in that: The envelope range of all response spectra that meet the requirements is used as the value range of the response spectrum of the MAD station; the maximum and minimum values ​​of the PGA of each component of all results are used as the value range of the PGA of each component of the MAD station; finally, the acceleration waveform that meets the requirements, the range of the acceleration response spectrum and the value range of the PGA of the MAD station are obtained.

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