Seabed free site accurate calibration method combining HVSR and 2D-GIT

Abstract

The invention provides a seabed free site accurate calibration method combining HVSR and 2D-GIT. According to the method, on the basis of submarine seismological observation data, HVSR and 2D-GIT are adopted to obtain submarine site transfer functions respectively, and a submarine free site is accurately calibrated through difference analysis of the site transfer functions; comprising the steps of seabed seismic data acquisition and preprocessing, HVSR spectrum ratio extraction, two-dimensional earth crust attenuation model modeling, 2D-GIT inversion and data fusion, conjoint analysis and environmental parameter correction, site type evaluation and dynamic parameter calibration. The characteristic that the HVSR technology is obviously influenced by local landforms when the horizontal transfer function of the seabed site is evaluated and the characteristic that the 2D-GIT technology can accurately evaluate the horizontal transfer function of each type of seabed site are jointly utilized, and analysis results of the two methods are compared. The method achieves the evaluation of the type of the seabed site and the more accurate and reliable positioning and characteristic evaluation of the free seabed site, effectively makes up for the limitation of a single technology, and provides a comprehensive and accurate type of the seabed site.

Description

Technical Field

[0001] The present invention relates to a precise calibration method for a submarine free field combining HVSR and 2D - GIT, belonging to the technical field of marine seismic calibration. Background Art

[0002] Due to the existence of plate boundary subduction zones, volcanic zones, sea water, complex terrain, and multiphase sediments, the strong ground motions in the sea area and land area caused by earthquakes exhibit significantly different characteristics. However, due to the lack of marine strong motion observation records, land strong motion records are often used for the seismic response analysis of marine structures. Inappropriate seismic input may lead to significant deviations in the predicted results of structural responses, which in turn has a negative impact on seismic design. Therefore, accurately calculating the seismic response characteristics of marine engineering sites is crucial for ensuring the seismic safety of marine engineering.

[0003] In recent years, the HVSR (horizontal - to - vertical spectral ratio) technique has been widely used in the analysis of seismic response characteristics of submarine sites because of its advantage of directly and quickly estimating the horizontal transfer function of submarine sites using submarine seismic observation records and ambient noise data. The HVSR technique can infer the transfer function characteristics of engineering sites by recording the natural vibrations of the ground without expensive or complex drilling operations. This technique is considered particularly suitable for areas with limited groundwater or difficult drilling, such as sandy coasts. However, the latest research shows that when the HVSR technique is directly applied to submarine sites, since most submarine sites are non - free fields, the vertical seismic response is affected by objective factors such as local topography, sediment layer thickness, and sea water pressure, and the horizontal site transfer function estimated by the HVSR technique often has significant deviations; Therefore, relying solely on the HVSR technique in the marine environment cannot provide sufficient detailed information on the transfer function of engineering sites and the underground stratigraphic structure. Especially under complex hydrogeological conditions, HVSR cannot achieve precise calibration of submarine free fields and cannot finely analyze the stratigraphic structure; To solve the above - mentioned technical problems, a precise calibration method for a submarine free field combining HVSR and 2D - GIT is proposed. Summary of the Invention

[0004] The present invention provides a precise calibration method for a submarine free field combining HVSR and 2D - GIT to solve or alleviate the technical problems existing in the prior art and at least provide a beneficial option.

[0005] The technical solution of the present invention is realized as follows: A precise calibration method for a submarine free field combining HVSR and 2D - GIT, comprising the following steps: S1. Submarine seismic data acquisition and preprocessing, that is, deploying submarine seismographs and auxiliary positioning equipment in the target sea area to obtain the original seismic wave signals and submarine topography data; S2. Conduct HVSR spectral ratio analysis based on the seismic record data, extract the horizontal and vertical Fourier amplitude spectra and spectral ratio characteristics of the submarine site, and thus derive the corresponding horizontal transfer function of the site; S3. Construct a two-dimensional submarine crust attenuation structure model with lateral inhomogeneity characteristics as the input for 2D-GIT inversion; S4. Use the two-dimensional generalized linear inversion 2D-GIT technology to process the collected submarine seismic data, extract more accurate horizontal transfer function information of the site, and realize the data fusion with the HVSR results; S5. Conduct a joint analysis of the site transfer function results extracted by the HVSR and 2D-GIT methods, identify the differences in frequency and amplitude characteristics between the two, derive the accurate vertical transfer function of the target site, and perform dynamic compensation and correction by introducing multi-source parameters such as the marine environmental temperature field and sound speed profile; S6. Based on the extracted characteristic parameters, conduct discrimination and accuracy evaluation of the submarine site type, determine whether it meets the definition criteria of the submarine free field, and output the site dominant period and site response parameter indicators; S7. Carry out dynamic parameter calibration of the submarine site.

[0006] Further preferably, in S1, at least three or more submarine seismographs and underwater acoustic beacon systems are deployed in the predetermined sea area, and the accurate coordinate positions of the control points are determined by using the triangulation method or differential GPS joint measurement technology according to the geometric relationship of the target site, ensuring that the survey ship is within the action radius of the underwater acoustic beacon during the data acquisition process; underwater high-precision topographic point cloud data is obtained through a multibeam sounding system, and the extraction result of the center of the laser stripe is optimized by combining the gray centroid method.

[0007] Further preferably, the data preprocessing steps in S1 include: Conduct quality assessment and signal-to-noise ratio analysis on the original seismic records collected by the seismographs, identify and eliminate abnormal points by using seismic data processing software, apply swell filtering technology to remove the influence of low-frequency noise caused by ocean current disturbances, and at the same time correct the systematic deviation of the acquisition positioning information, and set reasonable positioning time intervals and geographic coordinate systems.

[0008] Further preferably, in S2, a multi-channel synchronous recording system is used to collect the seismic waveform signals in the target area, the amplitude spectra in the horizontal and vertical directions are calculated through fast Fourier transform, and the HVSR spectral ratio curve is obtained accordingly. The fundamental resonance frequency is identified by analyzing the peak position of the spectral ratio curve, and combined with the empirical formula Estimate the corresponding sediment layer thickness.

[0009] Further preferably, in the step S3, the topographic point cloud data obtained from different survey lines is spatially registered by the ICP algorithm, and the feature points are matched and analyzed to optimize the coordinate transformation matrix; a two-dimensional seabed crust attenuation structure model with lateral non-uniformity is established by the 2D-GIT inversion technique.

[0010] Further preferably, in the step S4, an accurate horizontal transfer function of the seabed site is obtained by the 2D-GIT inversion technique. The sediment layer parameters, topographic data extracted by HVSR, the horizontal transfer function of the site significantly affected by local topography, and the horizontal transfer function of the site obtained by 2D-GIT are compared and analyzed to obtain information such as the topographic gradient index, the dominant frequency of the site, and the difference between the horizontal and vertical site transfer functions of the target seabed site, and then its site type is evaluated. On this basis, if the shapes of the horizontal transfer functions of the seabed site obtained by HVSR and 2D-GIT and the fundamental resonance frequencies corresponding to the peaks are all less different, and the shape of the vertical transfer function has no abnormal deformation below 10 Hz, the target seabed site can be accurately evaluated as a seabed free field.

[0011] Further preferably, in the step S5, the original signals output by various sensors are temperature compensated to correct the error caused by the fluctuation of seawater temperature on the voltage response of the iridium metal electrode. Based on the regional sound velocity profile data obtained by the Argo buoy, the sound signal path is refracted and corrected according to Snell's law, and the frequency characteristics of the site transfer function are further adjusted through the deviation between the measured sound velocity and the model sound velocity.

[0012] Further preferably, in the step S6, based on the comparison between the seismic response data of the target area and the measured results of the standard hydrophone, the reliability and stability of the extracted site transfer function are evaluated, the error range is controlled within the sediment layer thickness of ±0.05, and a high-resolution distribution map of the regional site dominant period and the frequency-related site transfer function is output.

[0013] Further preferably, in the step S7, a standard seawater buffer solution is used to calibrate the free field response of sensor devices such as acoustic hydrophones and seismometers, the pose change of the device is compensated by a cold atom interferometric gyroscope, and high-precision underwater navigation is realized through a multibeam sonar system. Combining the position correction data output by the real-time differential positioning system, the dynamic update and real-time adjustment of the calibration model are realized.

[0014] Due to the above technical solutions adopted in the embodiments of the present invention, the following advantages are achieved: 1. The present invention uses the HVSR method to preliminarily process submarine seismic data, and efficiently extracts the horizontal and vertical amplitude spectrum characteristics of the submarine site and the horizontal transfer function of the site through fast Fourier transform, which can quickly identify the resonance frequency of the site and the characteristics of the sediment layer, and is applicable to large-scale and preliminary screening site analysis; by combining the 2D-GIT technology to establish a two-dimensional crust attenuation structure model with lateral inhomogeneity, the response characteristics of the site and the horizontal transfer function are further finely inverted quantitatively, realizing a site characteristic description with higher resolution and stronger geological interpretation ability. 2. The present invention utilizes the characteristics that the calculation result of the horizontal transfer function of the submarine non-free site is significantly affected by local complex terrain, sediment layer thickness variation and seawater in the submarine non-free site, and jointly analyzes and cross-verifies this information with the accurate horizontal transfer function of the site obtained by 2D-GIT inversion; by comparing the characteristic dimensions of the extraction results of the two methods, the present invention can accurately judge whether the site meets the condition of "submarine free site", so as to realize the reliable calibration of the submarine free site and divide the types of sea area sites.

[0015] The above summary is only for the purpose of the specification and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments and features described above, further aspects, embodiments and features of the present invention will be readily apparent by reference to the drawings and the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0017] Figure 1 It is a flowchart of the method of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] In the following, only some exemplary embodiments are briefly described. As those skilled in the art can recognize, the described embodiments can be modified in various different ways without departing from the spirit or scope of the present invention. Therefore, the drawings and the description are considered to be exemplary in nature rather than restrictive.

[0019] The embodiments of the present invention will be described in detail below with reference to the drawings.

[0020] As Figure 1As shown in the figure, an embodiment of the present invention provides an accurate calibration method for a submarine free field combining HVSR and 2D-GIT, including the following steps: S1. Submarine seismic data acquisition and preprocessing: Deploy submarine seismographs and control points. Layout submarine seismographs and hydroacoustic beacons in the target sea area. Use the three-point space intersection method or GPS joint measurement technology to determine the coordinates of the control points, ensure that the survey ship is within the effective horizontal distance of the beacon, conduct multi-beam bathymetric data acquisition, obtain high-resolution submarine terrain point cloud data through a multi-beam sonar, combine the gray centroid method to optimize the extraction accuracy of the laser stripe center, and construct an initial two-dimensional terrain model. During data preprocessing, use marine survey software to remove outliers, filter swell waves, and correct fixed biases from the original data, and set the positioning recording interval and coordinate type; S2. Use a seismic recorder to synchronously collect seismic wave signal data, select high-quality signal time periods for HVSR analysis, calculate the spectral ratio of the horizontal component and the vertical component of the seismic wave, draw the horizontal transfer function curve of the site, and identify the fundamental resonance frequency corresponding to its peak, estimate the sediment layer thickness, and combine with an empirical formula to estimate the corresponding sediment layer thickness; S3. Two-dimensional submarine geological modeling, terrain data optimization: Use the ICP algorithm to register the submarine point cloud data obtained from multiple survey lines, optimize the coordinate transformation relationship through a feature point matching algorithm, and enhance the spatial consistency of the terrain model. During the construction of the two-dimensional submarine geological model, combine multi-beam bathymetric data with the submarine reflection acoustic characteristics to construct a geological structure model with lateral non-uniformity; S4. 2D-GIT joint inversion and data fusion, parameter joint inversion: Input the laterally non-uniform two-dimensional submarine crust attenuation model into the generalized linear inversion algorithm to obtain the horizontal transfer function of the target submarine site, further process the data, obtain the amplitude and frequency characteristics of the horizontal transfer function of the site, calculate information such as the dominant frequency of the regional site and the bedrock burial depth, conduct a difference analysis with the horizontal transfer function of the site obtained by HVSR, obtain the terrain gradient parameter of the site, judge the site type, and accurately calibrate the submarine free field; S5. Environmental parameter dynamic correction, temperature background correction: Perform temperature compensation on the sensor data to reduce the influence of seawater temperature changes on the measurement accuracy of iridium metal electrodes and sensors, conduct sound velocity profile correction, and based on Snell's acoustic ray theory, use the sound velocity profile data provided by Argo buoys to correct the sound signal propagation path error; S6. Model verification and accuracy evaluation: Compare and verify the obtained seafloor site transfer function with the output data of a standard hydrophone or other reference instruments, control the calibration error within the sediment layer thickness of ±0.05, ensure the reliability of the inversion results, and conduct dynamic monitoring and evaluation: Output the distribution map of the site transfer function related to the basic period and frequency of the site to support the seismic design of ocean engineering and disaster risk assessment; S7. Dynamic parameter calibration: Use a standard seawater buffer system to replace traditional chemical reagents to calibrate the acoustic hydrophone and seismometer in a free field, reduce system errors, combine a cold atom interferometer gyroscope with a multibeam sonar to achieve dynamic parameter calibration of an underwater autonomous navigation and positioning system, improve data stability under complex terrains, combine real-time differential positioning data to achieve dynamic model updates, and improve the long-term monitoring ability under complex seafloor environments.

[0021] In one embodiment, in S1, after selecting the target sea area, deploy multiple seafloor seismic nodes, use a land-based detection system to perform signal rotation processing on the horizontal (X) and vertical (Y) components of the seismic nodes to determine the installation orientation and initial attitude of each node, lay out control points in combination with an underwater acoustic beacon system, and achieve high-precision positioning of the seafloor nodes through the combination of underwater acoustic time difference positioning and land-based differential GPS joint measurement technology. The measured positioning error is controlled within 0.05 meters to meet the fine modeling accuracy requirements. Synchronously collect sonar data for verification, and the regression model accuracy reaches R² = 0.7221‌23. Use a three-color laser reference mark (red, green, purple), and based on the Tyndall effect, enhance the recognition of the laser in turbid water to assist the drone in achieving centimeter-level relative coordinate positioning accuracy.

[0022] In one embodiment, in S2, select the band with a relatively high signal-to-noise ratio in the seismic records for analysis, analyze the H / V spectral ratio of the seismic records, identify the fundamental resonance frequency (1.77 - 10.48 Hz), and calculate the sediment layer thickness through an empirical formula, and perform high-order resonance correction. For thick sediment layer areas (>50 meters), introduce high-order resonance peak correction to avoid underestimation of the thickness caused by a single frequency.

[0023] In one embodiment, in S3, perform registration processing on the multibeam bathymetry data obtained in step S1 and the high-density point cloud data obtained by the laser scanning system. The algorithm performs rigid registration on the spatial data set and optimizes its three-dimensional spatial consistency through the process of minimizing the inter-point residuals to ensure that the data collected by different devices are highly matched in the same coordinate system. Combine the sediment layer parameters extracted by the HVSR method and input them into a two-dimensional modeling system to establish a geological model with lateral non-uniformity (replacing the vertical sound velocity gradient) to reduce the sound ray bending error; iteratively optimize the bedrock burial depth, and set the convergence condition to the difference between two adjacent inversion results < 2%.

[0024] In one embodiment, in S4, a horizontally non-uniform two-dimensional seabed crust attenuation model is input into the generalized linear inversion 2D-GIT algorithm to obtain the site horizontal transfer function of the target seabed site. Further process the data to obtain the amplitude and frequency characteristics of the site horizontal transfer function, and calculate the dominant frequency information of the regional site (1.51 - 10.90 Hz). Through differential analysis with the site horizontal transfer function obtained by HVSR, obtain the site terrain gradient parameter (0.03 - 0.50), judge the site type (steep, flat), and accurately calibrate the seabed free field (flat type, the dominant frequencies of the site obtained by HVSR and 2D-GIT are 4.39 Hz and 4.06 Hz respectively, and the vertical transfer function of the site fluctuates around 0.8 below 10 Hz).

[0025] In one embodiment, in S5, perform temperature background correction on the iridium metal electrode and the sensor to reduce the interference of seawater temperature change on the measured value (error < 0.05H). Based on the actually measured sound velocity data of the Argo buoy, apply Snell's law to correct the sound signal propagation path and improve the sonar positioning accuracy.

[0026] When the present invention is in operation: Deploy submarine seismographs and control points, lay submarine seismographs and hydroacoustic beacons in the target sea area, use the three-point space intersection method or GPS joint measurement technology to determine the coordinates of the control points, ensure that the survey ship is within the effective horizontal distance of the beacons, conduct multi-beam bathymetric data acquisition, obtain high-resolution seabed terrain point cloud data through a multi-beam sonar, optimize the extraction accuracy of the laser stripe center by combining the gray centroid method, and construct an initial two-dimensional terrain model; During data preprocessing, use marine survey software to eliminate outliers, filter surge waves, and correct fixed biases in the original data, set the positioning record interval and coordinate type, conduct seismic signal analysis, collect seismic wave signals, calculate the horizontal and vertical Fourier amplitude spectra and spectral ratios, identify the fundamental resonance frequency corresponding to the peak of the spectral ratio curve, and estimate the sediment layer thickness. Convert the resonance frequency into the sediment layer thickness through an empirical formula; When optimizing terrain data, use the ICP algorithm to register the point clouds of adjacent survey lines, optimize the spatial transformation relationship through feature point matching, and enhance the spatial consistency of the terrain model; When conducting non-uniform geological modeling, combine multi-beam bathymetric data and acoustic reflection characteristics to construct a two-dimensional seabed geological structure model containing lateral non-uniformities. Input the two-dimensional non-uniform seabed crust attenuation model into the generalized linear inversion 2D-GIT algorithm to obtain the horizontal transfer function of the target seabed site. Further process the data to obtain the amplitude and frequency characteristics of the horizontal transfer function of the site, calculate the dominant frequency information of the regional site, conduct a difference analysis with the horizontal transfer function of the site obtained by HVSR to obtain the terrain gradient parameters of the site, judge the site type, and accurately calibrate the seabed free field; During iterative optimization, use the horizontal projection algorithm to perform a finite number of iterative calculations on the inversion results, converge to the sediment layer distribution and bedrock burial depth that meet the accuracy requirements, perform temperature compensation on the sensor data to reduce the influence of seawater temperature changes on the measurement accuracy of iridium metal electrodes and sensors, conduct sound velocity profile correction, and based on Snell's acoustic ray theory, use the sound velocity profile data provided by Argo buoys to correct the sound signal propagation path error. Verify the reliability of the calibration results by comparing with other instruments, such as standard hydrophones, and control the error range within ±0.05 of the sediment layer thickness. Dynamic monitoring and evaluation: Output the horizontal and vertical site transfer function distribution maps related to the dominant period and frequency of the site, support the seismic design of submarine engineering and disaster risk assessment, use a standard seawater buffer system to replace traditional chemical reagents to calibrate the free field of acoustic hydrophones and seismographs, reduce system errors, combine cold atom interferometric gyroscopes with multi-beam sonars to achieve dynamic parameter calibration of the underwater autonomous navigation and positioning system, improve data stability under complex terrains, combine real-time differential positioning data to achieve dynamic model updates, and improve the long-term monitoring ability under complex seabed environments.

[0027] As described above, it is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of various changes or substitutions, and these should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claimed rights.

Claims

1. An accurate calibration method for the free field on the seabed by combining HVSR and 2D-GIT, characterized in that, It includes the following steps: S1. Acquisition and preprocessing of submarine seismic data, that is, deploying submarine seismographs and auxiliary positioning devices in the target sea area to obtain original seismic wave signals and submarine topography data; S2. Conduct HVSR spectral ratio analysis based on seismic record data, extract the horizontal and vertical Fourier amplitude spectra and spectral ratio characteristics of the submarine site, so as to deduce the corresponding horizontal transfer function of the site; S3. Construct a two-dimensional submarine crust attenuation structure model with lateral non-uniformity characteristics as the input for 2D-GIT inversion; S4. Use the two-dimensional generalized linear inversion 2D-GIT technology to process the collected submarine seismic data, extract more accurate horizontal transfer function information of the site, and realize data fusion with the HVSR results; S5. Conduct joint analysis on the site transfer function results extracted by the HVSR and 2D-GIT methods, identify the differences in frequency and amplitude characteristics between the two, deduce the accurate vertical transfer function of the target site, and perform dynamic compensation and correction by introducing multi-source parameters such as the marine environmental temperature field and sound speed profile; S6. Discriminate and evaluate the accuracy of the submarine site type based on the extracted characteristic parameters, judge whether it meets the definition criteria of the submarine free field, and output the site dominant period and site response parameter indicators; S7. Carry out dynamic parameter calibration of the submarine site.

2. The precise calibration method for a free seafloor site combining HVSR and 2D-GIT according to claim 1, wherein: In S1, at least three or more submarine seismographs and underwater acoustic beacon systems are deployed in the predetermined sea area, and the accurate coordinate positions of the control points are determined by using the triangulation method or differential GPS joint measurement technology according to the geometric relationship of the target site, ensuring that the survey ship is within the action radius of the underwater acoustic beacon during the data acquisition process; underwater high-precision terrain point cloud data is obtained through a multibeam sounding system, and the extraction result of the center of the laser stripe is optimized by combining the gray centroid method.

3. A precise calibration method for free seafloor fields combining HVSR and 2D-GIT according to claim 1, characterized in that: The data preprocessing steps in S1 include: Conduct quality assessment and signal-to-noise ratio analysis on the original seismic records collected by the seismographs, identify and eliminate abnormal points using seismic data processing software, apply surge filtering technology to remove the influence of low-frequency noise caused by ocean current disturbances, and at the same time correct the systematic deviation of the acquisition and positioning information, and set reasonable positioning time intervals and geographic coordinate systems.

4. A precise calibration method for a submarine free field combining HVSR and 2D-GIT according to claim 1, characterized in that: In the step S2, a multi-channel synchronous recording system is used to collect seismic waveform signals of the target area, the amplitude spectra in the horizontal and vertical directions are calculated through fast Fourier transform, and the HVSR spectral ratio curve is obtained accordingly. By analyzing the peak position of the spectral ratio curve, the fundamental resonance frequency is identified, and the corresponding sediment layer thickness is estimated in combination with the empirical formula to estimate the corresponding sediment layer thickness.

5. A precise calibration method for a submarine free field combining HVSR and 2D-GIT according to claim 1, characterized in that: In S3, the spatial registration of the terrain point cloud data obtained from different survey lines is carried out by the ICP algorithm, and the feature points are matched and analyzed to optimize the coordinate transformation matrix; a two-dimensional submarine crust attenuation structure model with lateral non-uniformity is established by the 2D-GIT inversion technology.

6. A precise calibration method for a submarine free field combining HVSR and 2D-GIT according to claim 1, characterized in that: In the step S4, an accurate horizontal transfer function of the seabed site is obtained through the 2D-GIT inversion technique. The sediment layer parameters and topographic data extracted by HVSR, the horizontal transfer function of the site significantly affected by local topography, and the horizontal transfer function of the site obtained by 2D-GIT are compared and analyzed to obtain information such as the topographic gradient index, the dominant frequency of the site, and the difference between the horizontal and vertical site transfer functions of the target seabed site, so as to evaluate the site type. On this basis, if the shapes of the horizontal transfer functions of the seabed site obtained by HVSR and 2D-GIT and the fundamental resonance frequencies corresponding to the peaks have small differences, and the shape of the vertical transfer function has no abnormal deformation below 10 Hz, the target seabed site can be accurately evaluated as a seabed free field.

7. A precise calibration method for a free field on the seabed combining HVSR and 2D-GIT according to claim 1, characterized in that: In the step S5, temperature compensation is performed on the original signals output by various sensors to correct the error caused by the fluctuation of seawater temperature on the voltage response of iridium metal electrodes. Based on the regional sound velocity profile data obtained by Argo floats, the refraction correction of the sound signal path is performed according to Snell's law, and the frequency characteristics of the site transfer function are further adjusted through the deviation between the measured sound velocity and the model sound velocity.

8. A precise calibration method for free-field seabed combining HVSR and 2D-GIT according to claim 1, characterized in that: In the step S6, based on the comparison between the seismic response data of the target area and the measured results of standard hydrophones, the reliability and stability of the extracted site transfer function are evaluated, and the error range is controlled within the sediment layer thickness of ±0.05, and a distribution map of the dominant period and frequency-related site transfer function of the high-resolution regional site is output.

9. A precise calibration method for free-field seabed combining HVSR and 2D-GIT according to claim 1, characterized in that: In the step S7, a standard seawater buffer solution is used to calibrate the free field response of sensor devices such as acoustic hydrophones and seismographs, the attitude change of the device is compensated by a cold atom interferometer gyroscope, and high-precision underwater navigation is realized through a multibeam sonar system. Combining the position correction data output by the real-time differential positioning system, the dynamic update and real-time adjustment of the calibration model are realized.

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