Method and system for automatically extracting and identifying related tectonic earthquake under constraint of three-dimensional geometric structure of fault

Abstract

The invention provides a method and system for automatically extracting and identifying related tectonic earthquakes under the constraint of a three-dimensional geometric structure of a fault, and relates to the technical field of earthquake activity analysis. According to the method, fault surface trace data, geological occurrence parameters and three-dimensional geometric parameters are obtained, the fault strike angle is determined through principal component analysis, the inclination angle is determined based on orthogonal vector decomposition, and then a three-dimensional fault plane and fault body geometric model is constructed through curved surface modeling; and under the constraint of the three-dimensional geometric structure, judging the spatial relationship between the seismic points in the seismic directory data and the fault, realizing the classification and identification of the fault-related tectonic earthquake, and outputting an analysis result. According to the invention, the spatial integrity of fault geometric expression and the tectonic earthquake identification precision are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of seismic activity analysis, in particular to a method and system for automatically extracting and identifying relevant tectonic earthquakes under the constraint of three-dimensional geometric structure of faults. BACKGROUND

[0002] In active fault research and seismic activity analysis, the common practice is to obtain fault surface traces based on remote sensing interpretation and geological mapping, and to interpret the strike, dip and inclination of the fault in combination with geological occurrence parameters; then the epicenter distribution in the earthquake catalog is compared with the fault distribution to determine which earthquakes may be related to a specific fault section, and further to form a tectonic earthquake distribution map and other results.

[0003] With the improvement of seismic network observation capability, continuous updating of earthquake catalog, and the enhancement of understanding of deep structure, fault research gradually shifts from two-dimensional expression based on surface traces to three-dimensional expression emphasizing the constraint of deep structure of faults; under this background, generating a three-dimensional geological model using the geometric distribution of faults, especially the deep structure characteristics, and identifying relevant tectonic earthquakes under the constraint of this model, while outputting seismic moment tensor map and b value and other statistical indicators, has become a processing direction closer to the needs of engineering analysis.

[0004] However, the existing work still has obvious deficiencies: the three-dimensional model constraint of the fault is often lacking in seismic activity analysis, resulting in insufficient accuracy of relevant active tectonic earthquake analysis; in areas where active faults are developed in a crisscross manner, it is more difficult to accurately identify earthquakes related to faults only by relying on two-dimensional trace comparison.

[0005] Therefore, a technical solution is needed that can automatically calculate the occurrence from the fault surface traces and generate a three-dimensional model of the fault, and complete the identification of relevant tectonic earthquakes and the output of results under the constraint of the three-dimensional model, to obtain the three-dimensional model of the fault, the earthquake distribution map, the seismic moment tensor map, the b value, and the output results along the strike and perpendicular to the strike. SUMMARY

[0006] In order to overcome the deficiencies of the prior art, the purpose of the present application is to provide a method and system for automatically extracting and identifying relevant tectonic earthquakes under the constraint of three-dimensional geometric structure of faults, which overcomes the problem of insufficient dimension of fault geometric expression and low accuracy of tectonic earthquake determination in the prior art by constructing a three-dimensional geometric structure of faults and identifying tectonic earthquakes under the constraint of this structure.

[0007] To achieve the above purpose, the present application provides the following solutions:

[0008] A method for automatically extracting and identifying relevant tectonic earthquakes under the constraint of three-dimensional geometric structure of faults, comprising:

[0009] Obtaining fault surface trace data, geological occurrence parameters and three-dimensional geometric parameters, the fault surface trace data comprising a plurality of spatial coordinate points arranged in sequence;

[0010] Performing principal component analysis processing on the fault surface trace data to obtain a fault strike angle;

[0011] Generating two dip angle candidate values based on the strike angle using orthogonal vector decomposition processing, and receiving a selection input of the dip angle candidate values to determine a dip angle; wherein the two dip angle candidate values differ by 180 degrees and are both perpendicular to the fault strike direction determined by the strike angle;

[0012] Generating a three-dimensional fault surface geometric model using NURBS surface modeling based on the strike angle, the dip angle and a dip parameter in the geological occurrence parameters;

[0013] Determining a length of the fault body along the dip direction based on a vertical height parameter, a thickness parameter in the three-dimensional geometric parameters and the dip parameter, and extending the three-dimensional fault surface geometric model along the dip direction determined by the dip angle under the constraint of the length, and offsetting the three-dimensional fault surface geometric model along the normal direction of the three-dimensional fault surface geometric model according to the thickness parameter, to generate a fault body geometric model; wherein the length is converted into a height value consistent with the length unit of the spatial coordinate points after the length is converted into the height value by the vertical height parameter, and the length is determined by the ratio of the height value to the sine value corresponding to the dip parameter, and the length is degenerated to the height value when the sine value is zero;

[0014] Obtaining seismic catalog data, and determining a plurality of seismic points based on the seismic catalog data, determining the spatial relationship between the seismic points and the fault according to the three-dimensional fault surface geometric model and the fault body geometric model, and classifying the seismic points into fault surface points located on the three-dimensional fault surface geometric model, fault body points located inside the fault body geometric model and fault points located outside the fault body geometric model, to identify fault-related tectonic earthquakes;

[0015] Outputting and exporting analysis results; the analysis results include a three-dimensional fault model composed of the three-dimensional fault surface geometric model and the fault body geometric model, a seismic distribution map, a seismic MT map, a b value, a profile along the fault strike and a profile perpendicular to the fault strike.

[0016] Preferably, performing principal component analysis processing on the fault surface trace data to obtain a fault strike angle, comprising:

[0017] Performing data standardization processing on the spatial coordinate points;

[0018] computing a covariance matrix of the spatial coordinate points; performing eigenvalue decomposition on the covariance matrix to extract principal component directions;

[0019] computing the strike angle based on the principal component directions;

[0020] performing angle normalization on the strike angle to make the strike angle fall within a range of 0 to 360 degrees;

[0021] performing data quality check to identify and exclude abnormal spatial coordinate points.

[0022] Preferably, generating two dip angle candidates based on the strike angle using an orthogonal vector decomposition process and receiving a selection input of the dip angle candidates to determine a dip angle, comprises:

[0023] obtaining a first dip angle candidate by adding ninety degrees to the strike angle, and obtaining a second dip angle candidate by subtracting ninety degrees from the strike angle;

[0024] performing angle normalization on the first and second dip angle candidates by 360 degrees;

[0025] performing geological reasonableness verification on the first and second dip angle candidates;

[0026] outputting direction text descriptions of the first and second dip angle candidates, and receiving the selection input to determine the dip angle.

[0027] Preferably, generating a three-dimensional fault surface geometric model using a NURBS surface modeling, comprises:

[0028] generating a control point grid according to the spatial coordinate points, the strike angle, the dip angle and the dip parameter;

[0029] setting the degree of NURBS surface in U direction and V direction;

[0030] creating a NURBS surface and loading the control point grid;

[0031] performing surface refinement and optimization on the NURBS surface to obtain the three-dimensional fault surface geometric model.

[0032] Preferably, the step of generating the fault body geometric model comprises:

[0033] extending the three-dimensional fault surface geometric model along the dip direction under the extension length constraint;

[0034] offsetting the three-dimensional fault plane geometry model along the normal direction according to the thickness parameter to form a fault volume boundary;

[0035] closing the fault volume boundary to form the fault volume geometry model;

[0036] generating a triangular mesh representation of the fault volume geometry model.

[0037] Preferably, the length of the continuation is determined by a ratio of the height value of the vertical height parameter converted into the same length unit as the spatial coordinate point to a sine value corresponding to the dip angle parameter, including:

[0038] when the spatial coordinate point uses meters as the length unit, the vertical height parameter in kilometers is converted into the height value in meters;

[0039] when the spatial coordinate point uses kilometers as the length unit, the vertical height parameter is kept as the height value.

[0040] Preferably, seismic catalog data is obtained, and a plurality of seismic points are determined based on the seismic catalog data. The spatial relationship between the seismic points and the fault is determined according to the three-dimensional fault plane geometry model and the fault volume geometry model. The seismic points are classified into fault plane points located on the three-dimensional fault plane geometry model, fault volume points located inside the fault volume geometry model, and fault points located outside the fault volume geometry model, including:

[0041] automatically loading the seismic catalog data and supporting CSV format and TXT format;

[0042] a plurality of seismic points are obtained based on the seismic catalog data;

[0043] a classification label is generated for each seismic point; the classification label is a fault plane point, a fault volume point, or a fault point;

[0044] a CSV file containing the seismic points and the classification labels is exported, and a seismic distribution statistical report is generated.

[0045] Preferably, the analysis results are output and exported, including:

[0046] generating a top view mode seismic distribution map, an oblique view mode seismic distribution map, and a perspective view mode seismic distribution map;

[0047] generating the along-fault strike profile and the perpendicular to fault strike profile;

[0048] superimposing geological occurrence annotation information in the seismic distribution map and the profile;

[0049] deriving the seismic profile and the section.

[0050] Preferably, the outputting and deriving the analysis result further comprises:

[0051] when the fault surface trace data is represented in latitude-longitude coordinates, converting the latitude-longitude coordinates into local meter-based coordinates representation, displaying the local meter-based coordinate information in the seismic profile and the section, and deriving the analysis result containing the local meter-based coordinate information.

[0052] A system for automatically extracting and identifying relevant structural seismic under the constraint of three-dimensional geometry of faults, comprising:

[0053] a fault surface trace data acquisition unit, configured to acquire fault surface trace data, geological occurrence parameters and three-dimensional geometric parameters, the fault surface trace data containing a plurality of spatial coordinate points arranged in sequence;

[0054] a strike angle solving unit, configured to perform principal component analysis processing on the fault surface trace data to obtain a fault strike angle;

[0055] a dip angle determining unit, configured to generate two dip angle candidate values based on the strike angle using orthogonal vector decomposition processing, and receive selection input of the dip angle candidate values to determine a dip angle; wherein the two dip angle candidate values differ by 180 degrees and are both perpendicular to the fault strike direction determined by the strike angle;

[0056] a fault surface geometry modeling unit, configured to generate a three-dimensional fault surface geometry model using NURBS surface modeling based on the strike angle, the dip angle and the dip angle parameter in the geological occurrence parameters;

[0057] a fault body geometry construction unit, configured to determine the extension length of the fault body along the dip direction based on the vertical height parameter, the thickness parameter and the dip angle parameter in the three-dimensional geometric parameters, and extend the three-dimensional fault surface geometry model along the dip direction determined by the dip angle under the constraint of the extension length, and offset the three-dimensional fault surface geometry model along the normal direction of the three-dimensional fault surface geometry model according to the thickness parameter, to generate a fault body geometry model; wherein the extension length is determined by the ratio of the height value corresponding to the vertical height parameter to the sine value corresponding to the dip angle parameter after the vertical height parameter is converted into a height value consistent with the length unit of the spatial coordinate points, and the extension length is degenerated into the height value when the sine value is zero;

[0058] An earthquake spatial determination unit is constructed to acquire earthquake catalog data and determine multiple earthquake points based on the earthquake catalog data. The spatial relationship between the earthquake points and the fault is determined according to the three-dimensional fault plane geometry model and the fault body geometry model. The earthquake points are classified into fault plane points located on the three-dimensional fault plane geometry model, fault body points located inside the fault body geometry model, and fault body points located outside the fault body geometry model, so as to identify fault-related tectonic earthquakes.

[0059] The analysis result generation and export unit is used to output and export the analysis results; the analysis results include a three-dimensional fault model composed of the three-dimensional fault plane geometric model and the fault body geometric model, a seismic distribution map, a seismic MT map, b-values, profiles along the fault strike and profiles perpendicular to the fault strike.

[0060] The present invention discloses the following technical effects:

[0061] This invention addresses the problem in existing technologies that rely solely on fault surface traces or two-dimensional projection relationships for tectonic seismic analysis, which fails to reflect the deep geometry of faults. By automating the processing of fault surface trace data, calculating the fault strike and dip angles, and introducing dip angle parameters and three-dimensional geometric parameters, a three-dimensional geometric model of the fault is constructed. This fundamentally solves the problem of insufficient dimensional representation of fault geometry, providing a reliable spatial constraint basis for tectonic seismic identification.

[0062] This invention automatically calculates the fault strike angle through principal component analysis and generates paired candidate values ​​for the dip angle based on orthogonal vector decomposition. The dip angle is then determined by manual selection of input, effectively avoiding the subjective bias caused by relying entirely on human experience to determine fault attitude parameters. This provides a clear data source and logical basis for the acquisition of fault geometric parameters, improving the rationality of fault geometric modeling.

[0063] Based on the geometric model of the fault plane, this invention introduces vertical height parameters, thickness parameters, and dip angle parameters to determine the extension length of the fault body along the dip direction and constructs a geometric model of the fault body. This expands the fault from a two-dimensional curved surface into a three-dimensional body structure with actual spatial thickness and extension range, thereby truly reflecting the extent occupied by the fault in space and overcoming the judgment distortion problem caused by the fault being analyzed only as a "zero-thickness plane" in the prior art.

[0064] This invention incorporates earthquake points from earthquake catalog data into the spatial relationship determination under the constraints of the three-dimensional geometric structure of the fault. By distinguishing between points on the fault plane, points within the fault body, and points outside the fault, it achieves a refined classification of tectonic earthquakes. Compared with the method of judging solely based on the planar distance from the epicenter to the fault trace, it significantly improves the accuracy and reliability of fault-related tectonic earthquake identification.

[0065] Based on the completion of three-dimensional geometric modeling of faults and determination of structural earthquakes, this invention further outputs three-dimensional fault models, earthquake distribution maps, earthquake MT maps, b-values, and profiles along and perpendicular to the fault strike, so that the fault geometric structure information and seismic activity analysis results are expressed in a unified manner, which is conducive to the comprehensive display and engineering application of active fault research results. Attached Figure Description

[0066] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0067] Figure 1 A flowchart of the method provided in an embodiment of the present invention;

[0068] Figure 2 A three-dimensional schematic diagram of the fault's three-dimensional geometric model and the spatial distribution of seismic points provided in an embodiment of the present invention;

[0069] Figure 3 A three-dimensional schematic diagram of the fault three-dimensional geometric model and the distribution of seismic points provided in an embodiment of the present invention;

[0070] Figure 4 A schematic diagram of the longitudinal projection of the fault three-dimensional geometric model and seismic points provided in the embodiments of the present invention;

[0071] Figure 5 A schematic diagram of magnitude-time distribution (MT) of seismic events within a fault body provided for an embodiment of the present invention;

[0072] Figure 6 This is a schematic diagram illustrating the magnitude-frequency relationship analysis of earthquake events within a fault body, provided in an embodiment of the present invention.

[0073] Figure 7 A schematic diagram of the seismic distribution profile along the fault strike direction provided in an embodiment of the present invention;

[0074] Figure 8 This is a schematic diagram of the seismic distribution profile along the vertical fault strike direction, provided as an embodiment of the present invention. Detailed Implementation

[0075] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0076] The purpose of this invention is to provide a method and system for automatically extracting and identifying relevant tectonic earthquakes under the constraints of three-dimensional fault geometry. This method integrates fault geometry modeling and seismic activity analysis, thereby improving the reliability and application value of fault-related tectonic earthquake identification results.

[0077] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0078] Figure 1 A flowchart of the method provided in the embodiments of the present invention, such as Figure 1 As shown, this invention provides a method for automatically extracting and identifying relevant tectonic earthquakes under the constraints of three-dimensional fault geometry, including:

[0079] Step 100: Obtain fault surface trace data, geological occurrence parameters, and three-dimensional geometric parameters. The fault surface trace data contains multiple spatial coordinate points arranged in sequence.

[0080] Step 200: Perform principal component analysis on the fault surface trace data to obtain the fault strike angle;

[0081] Step 300: Based on the strike angle, orthogonal vector decomposition is used to generate two candidate values ​​for the dip angle, and the selection input for the candidate values ​​for the dip angle is received to determine the dip angle; wherein, the two candidate values ​​for the dip angle are 180 degrees apart and are both perpendicular to the fault strike direction determined by the strike angle;

[0082] Step 400: Based on the strike angle, dip angle, and dip angle parameters in the geological occurrence parameters, a three-dimensional fault plane geometric model is generated using NURBS surface modeling.

[0083] Step 500: Based on the vertical height parameter, thickness parameter, and dip angle parameter in the three-dimensional geometric parameters, determine the extension length of the fault body along the dip direction. Under the constraint of the extension length, extend the three-dimensional fault plane geometric model along the dip direction determined by the dip angle. At the same time, offset the three-dimensional fault plane geometric model along the normal direction of the three-dimensional fault plane geometric model according to the thickness parameter to generate the fault body geometric model. Among them, the extension length is converted from the vertical height parameter to a height value consistent with the length unit used by the spatial coordinate point, and then determined by the ratio of the height value to the sine value corresponding to the dip angle parameter. When the sine value is zero, the extension length is degenerated into the height value.

[0084] Step 600: Obtain earthquake catalog data and determine multiple earthquake points based on the earthquake catalog data. Determine the spatial relationship between earthquake points and faults according to the three-dimensional fault plane geometry model and fault body geometry model. Classify earthquake points into fault plane points located on the three-dimensional fault plane geometry model, fault body points located inside the fault body geometry model, and fault body points located outside the fault body geometry model, in order to identify fault-related structural earthquakes.

[0085] Step 700: Output and export the analysis results; the analysis results include a three-dimensional fault model consisting of a three-dimensional fault plane geometry model and a fault body geometry model, a seismic distribution map, a seismic MT map, b-values, profiles along the fault strike, and profiles perpendicular to the fault strike.

[0086] This embodiment is implemented on a general-purpose computer platform, and the software runtime environment supports high-level interpreted programming languages, with version 3.8 or higher. The program calls a numerical computing library to perform vector operations, matrix operations, and eigenvalue decomposition calculations required for principal component analysis; it calls a scientific computing library to perform mathematical function operations; it calls a plotting library to output two-dimensional graphics; and it calls a three-dimensional visualization library to display the three-dimensional scene. The three-dimensional rendering layer uses a three-dimensional graphics engine to display and interactively render the geometric mesh, and the cross-sectional geometric model is generated using a surface modeling library based on non-uniform rational B-splines. When manual input is required, a graphical interface framework can be optionally configured for parameter configuration, selection of candidate values ​​for the inclination angle, and result browsing. The above-described hardware and software environment is merely one implementation method of the present invention and does not constitute a limitation on the scope of protection of the present invention.

[0087] This embodiment uses a configuration file-driven approach to organize input data and analysis parameters. The configuration file adopts a JSON structure and includes at least four types of fields: fault traces, geological attitude, geometric parameters, and visualization parameters. The fault trace field describes the source type of the fault surface trace data, the data file path, the Chinese name of the fault, whether fuzzy name matching is enabled, and the coordinate system type. This is used to accurately locate and read the fault surface trace data of the target fault from the specified file. The geological attitude field describes the attitude calculation method, dip angle parameters, and dip angle candidate value selection options. The attitude calculation method indicates the processing flow of automatically calculating the strike angle first and then selecting dip angle candidate values. The geometric parameter field includes vertical height parameters, whether to use only vertical height calculation, and thickness parameters. "Use only vertical height calculation" controls whether dip angle parameters are used in the calculation of the extended length. The visualization parameter field controls whether to display seismic points, the output directory of the analysis results, and the output file name.

[0088] In this embodiment, the northern segment of the Xianshuihe Fault is taken as the analysis object. The fault trace data source in the configuration file is set to gmt, the fault trace file path is set to data / CN-faults.gmt, the Chinese name of the fault is set to “Xianshuihe Fault|Northern Segment”, fuzzy name matching is set to false, and the coordinate system is set to lonlat. In the geological attitude parameters, the attitude calculation method is set to automatic strike calculation with dip angle selection, the dip angle parameter is set to 75°, and the dip angle selection option is set to option1. In the geometric parameters, the vertical height parameter is set to 15km, “only vertical height calculation” is set to false, and the thickness parameter is set to 0.2km. In the visualization parameters, whether to display seismic points is set to true, the output directory is set to output / xianshuihe, and the output file name is set to northern_segment_3d.png. During program execution, the system first reads the fault surface trace data with corresponding Chinese names from the fault trace file, performs principal component analysis on the fault surface trace data to calculate the strike angle, then generates two candidate dip angle values ​​based on the strike angle, and determines the dip angle according to option1. Under the constraints of the dip angle parameter, vertical height parameter, and thickness parameter, a three-dimensional fault plane geometric model and a fault body geometric model are generated. Under the constraints of the three-dimensional fault geometry, seismic catalog data is loaded, spatial relationships of earthquake points are determined, and finally, the analysis results, such as the three-dimensional fault model and earthquake distribution map, are output.

[0089] In this embodiment, batch processing is performed on the Longmenshan fault zone. The batch processing fields in the configuration file include the input directory data / longmenshan / , the output directory results / longmenshan / , and a list of fault segments. The list of fault segments includes "Longmenshan Fault | North Segment", "Longmenshan Fault | Middle Segment", and "Longmenshan Fault | South Segment", for a total of three fault segments. The common parameters are uniformly set as follows: dip angle 80°, vertical height 12km, and thickness 0.15km. After the batch processing program starts, it reads the corresponding fault surface trace data for each fault segment in the list, and repeatedly executes strike angle calculation, dip angle candidate value generation and selection, three-dimensional fault plane geometric model generation, fault body geometric model construction, and seismic point spatial relationship determination and analysis result output, so that each fault segment completes tectonic earthquake identification under a unified parameter system.

[0090] In this embodiment, when a standardized fault trace data file is lacking, the user directly inputs a set of sequentially arranged spatial coordinate points as the fault surface trace data. An example of these spatial coordinate points is six latitude and longitude coordinate points distributed along the directions of longitude 102.5 to 103.0 and latitude 30.2 to 30.7. After receiving the spatial coordinate points, the program automatically performs strike angle calculation and generates two corresponding dip angle candidate values ​​based on the given dip angle parameter of 70°. The dip angle is determined after receiving the user's input option 2. The calculation results are then output, including at least the strike angle and the dip angle, displayed as angle values, for example, in the format "Strike XXX°, Dip XXX°," so that the user can verify the attitude calculation results. Based on this, the generation of a three-dimensional fault plane geometric model and a fault body geometric model can continue, and the spatial determination and analysis results of the tectonic earthquake can be output.

[0091] Specifically, step 100 in this embodiment is implemented as follows:

[0092] This embodiment first acquires fault surface trace data, geological attitude parameters, and three-dimensional geometric parameters. The fault surface trace data characterizes the spatial distribution of the fault on the surface and is specifically composed of multiple sequentially arranged spatial coordinate points. Adjacent spatial coordinate points are connected sequentially to form a fault trace broken line. These spatial coordinate points can be represented in latitude and longitude coordinates or Cartesian coordinates. When using latitude and longitude coordinates, the longitude and latitude of the spatial coordinate points are represented in decimal degrees, for example, a longitude range of 102.5 to 103.0 and a latitude range of 30.2 to 30.7, reflecting the actual positional relationship of the fault at a regional scale. The geological attitude parameters describe the geometric attitude characteristics of the fault and include at least a dip angle parameter. The dip angle parameter represents the degree of inclination of the fault plane relative to the horizontal plane, with a value range of 0 to 90 degrees. In this embodiment, 70 degrees can be selected. 75 degrees or 80 degrees are used as quantitative examples to determine the vertical extension relationship of the fault plane in subsequent fault geometry modeling. The three-dimensional geometric parameters are used to define the geometric scale of the fault in space, including at least vertical height parameters and thickness parameters. The vertical height parameter is used to characterize the extension height of the fault in the deep direction, and its value can be 12 km or 15 km. The thickness parameter is used to characterize the geometric thickness of the fault body in the normal direction, and its value can be 0.15 km or 0.2 km. The above-mentioned fault surface trace data, geological occurrence parameters, and three-dimensional geometric parameters can be obtained from manual surveying data, existing geological data, or pre-organized data files. In this embodiment, they are used as the basic input data for subsequent fault strike calculation, fault plane geometry model construction, and fault body geometry model generation, thereby ensuring the clarity and feasibility of the method of the present invention in terms of the source and numerical range of geometric parameters.

[0093] In this embodiment, step 200 calculates the orientation of the fault surface trace data using principal component analysis, specifically as follows: This embodiment uses multiple sequentially arranged spatial coordinate points obtained in step 100 as input. First, data standardization is performed on these spatial coordinate points. Data standardization refers to removing the mean and unifying the scale of the horizontal coordinate components of the spatial coordinate points, ensuring comparability of coordinate components with different dimensions or amplitude ranges in subsequent statistical calculations. For example, when the spatial coordinate points are represented using latitude and longitude, this embodiment converts the spatial coordinate points to a unified planar length scale before... Standardization is performed, and the planar length scale can be measured in meters, allowing direct comparison of the horizontal distances between adjacent spatial coordinate points. In the quantitative example, the fault surface trace data can include no fewer than six spatial coordinate points, and the horizontal distance between adjacent spatial coordinate points can be within the range of 100m to 2000m, to ensure that the fault surface trace data can characterize the overall extension direction of the fault. After data standardization, this embodiment calculates the covariance matrix based on the standardized spatial coordinate points. The covariance matrix is ​​used to characterize the joint dispersion and correlation of the spatial coordinate points in two horizontal coordinate directions.

[0094] After calculating the covariance matrix, this embodiment performs eigenvalue decomposition on the covariance matrix to extract the principal component direction. The principal component direction refers to the horizontal vector direction that maximizes the projection variance of the spatial coordinate point in that direction, used to characterize the overall extension trend of the fault surface trace. This embodiment further determines the strike angle based on the principal component direction. The strike angle is an angle measured clockwise from geographic north, and angle normalization is performed on the strike angle to ensure it falls within the range of 0 to 360 degrees, so as to maintain consistency with commonly used geological attitude expressions. In the quantitative example, if the principal component direction points to the northeast quadrant, the strike angle can fall within the range of 30 to 80 degrees; if the principal component direction points to the northwest quadrant, the strike angle can fall within the range of 280 to 340 degrees. To improve the reliability of the strike angle calculation results, this embodiment performs a data quality check before or after principal component analysis. The data quality check is used to identify anomalous spatial coordinate points, including spatial coordinate points that deviate significantly from the overall trend of the fault trace and cause unreasonable sharp turns in local broken lines. In the quantitative example, this embodiment can identify spatial coordinate points with a turning angle greater than 120 degrees between adjacent broken line segments as candidate anomalous points, and perform elimination or replacement processing on the candidate anomalous points to make the strike angle more representative of the overall trend of the fault surface trace.

[0095] In this embodiment, step 300 is used to determine the dip angle of the fault based on the determined strike angle. This is achieved as follows: Based on the strike angle obtained in step 200, orthogonal vector decomposition is performed to obtain two opposing candidate dip angle values ​​corresponding to the strike angle. "Orthogonal vector decomposition" refers to constructing direction vectors perpendicular to the fault strike direction in the horizontal plane to characterize the possible dip directions of the fault plane. In this embodiment, by adding 90 degrees and subtracting 90 degrees from the strike angle, a first dip angle candidate value and a second dip angle candidate value are obtained. Both candidate dip angle values ​​are geometrically perpendicular to the fault strike direction determined by the strike angle, and differ by 180 degrees, thus fully covering the two possible opposite dip directions of the fault plane. In a quantitative example, when the strike angle is 45 degrees, the first dip angle candidate value can be 135 degrees, and the second dip angle candidate value can be 315 degrees, representing the two possible scenarios of the fault plane dipping southeast or northwest.

[0096] After obtaining two candidate dip angle values, this embodiment performs angle normalization processing on the first and second candidate dip angle values ​​to ensure that both fall within the range of 0 to 360 degrees, thus guaranteeing the consistency and comparability of angle expressions. Subsequently, a geological rationality verification is performed on the two candidate dip angle values. This verification determines whether the candidate dip angle values ​​are consistent with the regional tectonic background, the bending direction of the fault trace, or known geological knowledge. For example, unreasonable dip directions that clearly point to the outer side of the hanging wall of the fault are preferentially excluded. In the quantitative example, when the fault surface trace generally extends northeastward and the regional tectonic structure shows that the fault dips southeastward, candidate dip angle values ​​within the range of 90 to 180 degrees can be preferentially retained. After verification, this embodiment outputs the directional text descriptions corresponding to the first and second candidate dip angle values, such as "dipping northeast" or "dipping southwest," and receives selection input to determine the final dip angle to be adopted, thereby providing a unique and clear dip parameter for the subsequent construction of the fault plane geometric model.

[0097] In this embodiment, step 400 is used to construct a three-dimensional geometric representation of the fault under the constraints of the determined strike angle, dip angle, and dip angle parameters. The implementation is as follows: This embodiment uses multiple sequentially arranged spatial coordinate points obtained in step 100 as basic geometric constraints. These spatial coordinate points are projected onto the main extension direction consistent with the strike angle, and the dip angle is combined to determine the tilt direction of the fault plane in the horizontal plane. Simultaneously, the dip angle parameter from the geological occurrence parameters is introduced to limit the degree of tilt of the fault plane relative to the horizontal plane. Based on the above geometric constraints, this embodiment generates a control point grid in the fault trace extension direction and the dip extension direction. The control point grid consists of multiple rows and columns of control points, used to describe the overall morphology of the fault plane in space. In the quantitative example, the control point grid can have no fewer than 10 control points along the strike direction and no fewer than 5 control points along the dip direction to ensure that the fault plane has sufficient geometric resolution in both the length and dip directions, thereby reflecting the spatial variation trend of the fault plane from shallow to deep.

[0098] After generating the control point mesh, this embodiment further sets the degree of the non-uniform rational spline surface in two parameter directions. One parameter direction corresponds to the fault strike direction, and the other parameter direction corresponds to the fault dip direction, used to control the smoothness and bending capacity of the surface. Subsequently, a non-uniform rational spline surface is created based on the degree setting, and the control point mesh is loaded into the surface, so that the surface passes through or approximates the positions of each control point in space, thereby forming the initial fault plane geometry. To improve the continuity and smoothness of the fault plane geometry model, this embodiment performs surface refinement and optimization processing on the surface. The surface refinement is used to interpolate between control points to generate a higher density surface representation, and the surface optimization is used to reduce local irregular undulations and maintain the overall geometric trend of the fault plane. In the quantitative example, the maximum local undulation of the fault plane in the strike direction after refinement and optimization can be controlled within 50 m, so that the obtained three-dimensional fault plane geometry model not only meets the requirements of geological morphological continuity, but also serves as a stable geometric basis for subsequent fault body geometry model generation and spatial determination of structural earthquakes.

[0099] In this embodiment, step 500 is used to construct a fault body geometric model with actual spatial thickness and extension range based on the obtained three-dimensional fault plane geometric model. The implementation is as follows: This embodiment first introduces the vertical height parameter and thickness parameter from the three-dimensional geometric parameters obtained in step 100, and combines them with the dip angle parameter from the geological attitude parameters to determine the extension length of the fault body along the dip direction. The so-called "extension length" refers to the spatial distance the fault plane extends from the surface to depth in the dip direction, used to define the geometric scale of the fault body in the depth direction. In this embodiment, the extension length is determined by converting the vertical height parameter to a height value consistent with the length unit used for the spatial coordinate points, and combining it with the dip angle parameter reflecting the degree of inclination of the fault plane. In the quantitative example, when the vertical height parameter is 12km or 15km, and the dip angle parameter is 70°, 75°, or 80°, the extension length can reflect the reasonable extension range of the fault body from shallow to deep, thereby avoiding geometric distortion caused by the fault body being too short or too long.

[0100] After determining the extension length, this embodiment extends the three-dimensional fault plane geometric model generated in step 400 along the dip direction determined by the dip angle, under the constraint of the extension length, so that the fault plane unfolds from the surface to the depth. Subsequently, the three-dimensional fault plane geometric model is offset along its normal direction according to the thickness parameter to form mutually parallel boundary surfaces on both sides of the fault plane. The spacing between the boundary surfaces is defined by the thickness parameter, which is used to characterize the geometric thickness of the fault body in the normal direction. In the quantitative example, the thickness parameter can be 0.15 km or 0.2 km, so that the generated fault body has a clear spatial volume without obscuring the main geometric features of the fault plane due to excessive thickness. After completing the extension and normal offset, this embodiment closes the boundaries of the formed fault body to obtain a complete and closed fault body geometric model.

[0101] In a further preferred embodiment, this embodiment performs unit consistency processing on the calculation process of the extension length to ensure the consistency of the fault body geometric model under different coordinate representation conditions: when the spatial coordinate point uses meters as the length unit, this embodiment converts the vertical height parameter in kilometers into a height value in meters before participating in the determination of the extension length; when the spatial coordinate point uses kilometers as the length unit, the vertical height parameter is directly used as the height value to participate in the determination of the extension length. In the special case where the sine value corresponding to the dip angle parameter is zero, it indicates that the fault plane is in an approximately horizontal state. In this case, this embodiment degenerates the extension length to the height value to avoid unreasonable numerical amplification of the extension length. After completing the above processing, this embodiment can further generate a triangular mesh representation of the fault body geometric model for subsequent spatial determination and analysis results of tectonic earthquakes, thereby ensuring that the fault body geometric model meets the implementation requirements of the method of this invention in terms of geometric continuity, scale rationality, and application stability.

[0102] In this embodiment, step 600 is used to determine the spatial relationship between earthquake events and faults under the constraints of the three-dimensional geometric structure of the fault. The implementation is as follows: First, earthquake catalog data is obtained. This catalog data records the spatial location and basic attribute information of earthquake events that have occurred within the region, including at least the spatial location parameters corresponding to each earthquake event. This embodiment supports providing the earthquake catalog data in tabular form, for example, using comma-separated or text line-separated records, so that each record corresponds to one earthquake event. Based on the earthquake catalog data, this embodiment parses and obtains multiple earthquake points. These earthquake points represent the spatial location of each earthquake event. The spatial location of the earthquake points is consistent with the coordinate system used in the fault surface trace data in step 100 to ensure the accuracy of subsequent spatial relationship determination. In the quantitative example, the earthquake catalog data may contain dozens to thousands of earthquake points to reflect the distribution characteristics of seismic activity within a certain spatial range near the fault.

[0103] After obtaining the seismic points, this embodiment determines the spatial relationship between the seismic points and the fault based on the three-dimensional fault plane geometry model generated in step 400 and the fault body geometry model generated in step 500. Specifically, this embodiment compares the spatial position of each seismic point with the three-dimensional fault plane geometry model to determine whether the seismic point is located on the three-dimensional fault plane geometry model; simultaneously, it determines the inclusion relationship between the seismic point and the fault body geometry model to determine whether the seismic point is located inside the space defined by the fault body geometry model. Based on the above determination, this embodiment classifies the seismic points according to preset determination rules: when the seismic point is located on the three-dimensional fault plane geometry model, it is classified as a point on the fault plane; when the seismic point is not located on the fault plane but is located inside the fault body geometry model, it is classified as a point inside the fault body; when the seismic point is located outside the fault body geometry model, it is classified as a point outside the fault body. Through the above classification method, this embodiment can distinguish different types of seismic points on a three-dimensional spatial scale, thereby providing a clear basis for identifying fault-related tectonic earthquakes.

[0104] After classifying the earthquake points, this embodiment generates a corresponding classification label for each earthquake point. The classification label indicates whether the earthquake point belongs to a point on the fault plane, a point within the fault body, or a point outside the fault. Subsequently, the information containing the spatial location of the earthquake point and the classification label is exported as a structured data file to facilitate subsequent statistical analysis and result verification. Simultaneously, this embodiment generates an earthquake distribution statistical report based on the classification results to summarize the quantity distribution and spatial characteristics of earthquake points of different categories. In the quantitative example, the statistical report can reflect the proportion of points within the fault body to all earthquake points and the spatial concentration of points on the fault plane, thereby assisting in determining the correlation between faults and seismic activity. Through the above processing, this embodiment achieves tectonic earthquake identification based on the three-dimensional geometry of faults without relying on two-dimensional distance criteria.

[0105] In this embodiment, step 700 is used to visualize the three-dimensional geometric structure of the fault and the seismic identification results formed in steps 400 to 600, and to generate a traceable output. The implementation is as follows: This embodiment constructs a three-dimensional fault model based on the three-dimensional fault plane geometric model and the fault body geometric model, and generates a seismic distribution map by combining the seismic points and their classification labels obtained in step 600. The seismic distribution map includes at least a top view mode, an oblique view mode, and a perspective view mode. The top view mode is used to display the distribution of seismic points in the horizontal plane from a vertical direction; the oblique view mode is used to display the spatial confinement relationship of seismic points relative to the fault body; and the perspective view mode is used to display the overall spatial morphology of the three-dimensional fault model and the seismic points. In the quantitative example, this embodiment can provide seismic distribution maps from three different perspectives in the same output, and distinguish between points on the fault plane, points within the fault body, and points outside the fault body in the map, so as to intuitively compare the spatial clustering characteristics of different categories of seismic points.

[0106] In a further preferred embodiment, this embodiment generates a profile along the fault strike and a profile perpendicular to the fault strike. These profiles are used to demonstrate the correspondence between seismic points in the depth direction and the fault geometry. Specifically, the profile along the fault strike demonstrates the continuity of seismic activity along the fault strike direction, while the profile perpendicular to the fault strike demonstrates the relationship between the location of seismic points along the fault dip direction and the thickness range of the fault body. To enhance the geological interpretation capability of the results, this embodiment overlays geological attitude annotation information onto the seismic distribution map and the profiles. This geological attitude annotation information includes at least the direction indication and angle value annotation of the strike angle, dip angle, and dip angle parameter, enabling the output results to simultaneously express the fault geometry and the spatial distribution of seismic points. In a quantitative example, this embodiment can annotate the strike angle with angle values ​​ranging from 0 to 360 degrees and the dip angle parameter with angle values ​​ranging from 0 to 90 degrees to ensure the verifiability and reusability of the attitude annotation information.

[0107] In another preferred embodiment, when the fault surface trace data is represented by latitude and longitude coordinates, this embodiment converts the latitude and longitude coordinates into a local metric coordinate representation. This local metric coordinate representation is used to display planar location scale information in meters in the earthquake distribution map and the profile, so as to intuitively quantify the spatial distance and scale range between the earthquake point and the three-dimensional fault model. In the quantitative example, the display range of the local metric coordinates can cover a regional scale of 0 to 20,000 m near the fault trace, to meet the scale expression requirements of regional tectonic earthquake analysis. After completing the map generation and coordinate transformation, this embodiment exports the earthquake distribution map and the profile, and combines the three-dimensional fault model, earthquake MT map, b-value, and related maps to form the output of the analysis results, thereby realizing the graphical presentation and data storage of the fault-related tectonic earthquake identification conclusions.

[0108] like Figure 2 As shown in the figure, the three-dimensional geometric structure of the fault is formed by the extension of the fault surface traces into the depth. The semi-transparent three-dimensional geometric body represents the geometric model of the fault body, and the inclined plane at its center represents the geometric model of the three-dimensional fault plane. The red line segments in the figure represent the projection of the fault surface traces onto the surface. Multiple scattered points represent the spatial distribution of earthquake points, with different colors used to distinguish earthquake points located inside and outside the geometric model of the fault body. The vertical coordinate represents the depth direction, which is used to intuitively reflect the correspondence between earthquake points and the fault geometry in the vertical direction. This figure is used to show the overall constraint effect of the three-dimensional fault structure on the spatial distribution of earthquakes.

[0109] like Figure 3 As shown, this figure is Figure 2 The results of displaying the three-dimensional geometric model of the fault and the spatial distribution of seismic points from different observation perspectives are used to observe the spatial morphology of the fault body geometric model and the distribution characteristics of seismic points inside and outside it from another spatial perspective. By changing the perspective, the geometric extension of the fault body in the dip and strike directions and the clustering trend of seismic points relative to the fault plane can be observed more clearly, thereby verifying the rationality of the three-dimensional geometric model of the fault in spatial representation.

[0110] like Figure 4 As shown, this figure is the projection result of the three-dimensional geometric model of the fault and the seismic points in the vertical direction. The horizontal axis represents the planar position coordinates, and the vertical axis represents the depth. The semi-transparent area in the figure represents the range of the fault body geometric model in this projection direction. Seismic points located inside the area are displayed as one type of label, and seismic points located outside the area are displayed as another type of label. This figure is used to show the distribution relationship of seismic points in the depth direction relative to the fault body geometric model, so as to help determine whether seismic activity is controlled by the fault structure.

[0111] likeFigure 5 As shown in the figure, this figure shows the distribution of earthquake magnitudes at earthquake points located inside the fault body's geometric model over time. The horizontal axis represents time, and the vertical axis represents earthquake magnitude. This figure allows us to observe the temporal variation characteristics of seismic activity inside the fault body, which can be used to analyze the temporal evolution of fault-related tectonic earthquakes and provide basic data support for subsequent earthquake statistical analysis.

[0112] like Figure 6 As shown in the figure, this figure illustrates the relationship between the magnitude and cumulative frequency of earthquakes at earthquake points located within the geometric model of the fault body. The horizontal axis represents earthquake magnitude, and the vertical axis represents the cumulative number of earthquakes. The statistical curves obtained from the magnitude-frequency distribution relationship in the figure are used to calculate statistical parameters of seismic activity, including the b-value used to characterize the strength of seismic activity. This figure is used to quantitatively analyze the statistical characteristics of seismic activity within the fault body.

[0113] like Figure 7 As shown, this figure is a cross-sectional view generated along the fault strike direction, where the horizontal axis represents the distance along the fault strike direction and the vertical axis represents the depth; the shaded area in the figure represents the projection range of the fault body geometry model on the cross-section, and the scattered points represent different categories of seismic points, which can distinguish between seismic points located near the cross-section and those not located near the cross-section line; this cross-section is used to analyze the spatial distribution continuity of seismic points along the fault strike direction.

[0114] like Figure 8 As shown, this figure is a cross-sectional view generated perpendicular to the fault strike direction, where the horizontal axis represents the distance perpendicular to the fault strike direction and the vertical axis represents the depth. The figure marks the projection points of the fault surface traces on the cross-sectional location and shows the spatial range of the fault body geometry model in this cross-sectional direction. Through this cross-section, the distribution of earthquake points in the fault dip direction and their correspondence with the fault body thickness range can be observed intuitively, thereby helping to determine the spatial correlation between seismic activity and fault structure.

[0115] Corresponding to the above method, this embodiment also provides a system for automatically extracting and identifying relevant tectonic earthquakes under the constraints of three-dimensional fault geometry, including:

[0116] The fault trace data acquisition unit is used to acquire fault surface trace data, geological occurrence parameters and three-dimensional geometric parameters. The fault surface trace data includes multiple spatial coordinate points arranged in sequence.

[0117] The strike angle calculation unit is used to perform principal component analysis on the fault surface trace data to obtain the fault strike angle.

[0118] The dip angle determination unit is used to generate two dip angle candidate values ​​based on the strike angle using orthogonal vector decomposition processing, and to receive selection input for the dip angle candidate values ​​to determine the dip angle; wherein the two dip angle candidate values ​​differ by 180 degrees and are both perpendicular to the fault strike direction determined by the strike angle.

[0119] The fault plane geometry modeling unit is used to generate a three-dimensional fault plane geometry model based on the strike angle, the dip angle and the dip angle parameter in the geological attitude parameters using NURBS surface modeling.

[0120] A fault body geometry construction unit is used to determine the extension length of the fault body along the dip direction based on the vertical height parameter, thickness parameter, and dip angle parameter in the three-dimensional geometric parameters, and to extend the three-dimensional fault plane geometric model along the dip direction determined by the dip angle under the constraint of the extension length. At the same time, the three-dimensional fault plane geometric model is offset along the normal direction of the three-dimensional fault plane geometric model according to the thickness parameter to generate a fault body geometric model. The extension length is determined by converting the vertical height parameter into a height value consistent with the length unit used by the spatial coordinate points, and then by the ratio of the height value to the sine value corresponding to the dip angle parameter. When the sine value is zero, the extension length is degenerated into the height value.

[0121] An earthquake spatial determination unit is constructed to acquire earthquake catalog data and determine multiple earthquake points based on the earthquake catalog data. The spatial relationship between the earthquake points and the fault is determined according to the three-dimensional fault plane geometry model and the fault body geometry model. The earthquake points are classified into fault plane points located on the three-dimensional fault plane geometry model, fault body points located inside the fault body geometry model, and fault body points located outside the fault body geometry model, so as to identify fault-related tectonic earthquakes.

[0122] The analysis result generation and export unit is used to output and export the analysis results; the analysis results include a three-dimensional fault model composed of the three-dimensional fault plane geometric model and the fault body geometric model, a seismic distribution map, a seismic MT map, b-values, profiles along the fault strike and profiles perpendicular to the fault strike.

[0123] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple; relevant parts can be referred to the method section.

[0124] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for automatically extracting and identifying relevant structure seismic under the constraint of three-dimensional geometry of faults, characterized in that, The method comprises: acquiring fault surface trace data, geological occurrence parameters and three-dimensional geometric parameters, the fault surface trace data comprising a plurality of spatial coordinate points arranged in sequence; performing principal component analysis processing on the fault surface trace data to obtain a fault strike angle; generating two dip angle candidate values based on the strike angle using orthogonal vector decomposition processing, and receiving selection input of the dip angle candidate values to determine a dip angle; wherein the two dip angle candidate values differ by 180 degrees and are both perpendicular to the fault strike direction determined by the strike angle; generating a three-dimensional fault surface geometric model using NURBS surface modeling based on the strike angle, the dip angle and a dip parameter in the geological occurrence parameters; determining a length of fault body extension along the dip direction based on a vertical height parameter, a thickness parameter in the three-dimensional geometric parameters and the dip parameter, and extending the three-dimensional fault surface geometric model along the dip direction determined by the dip angle under the constraint of the length of fault body extension, and offsetting the three-dimensional fault surface geometric model along the normal direction of the three-dimensional fault surface geometric model according to the thickness parameter, to generate a fault body geometric model; wherein the length of fault body extension is converted into a height value consistent with the length unit of the spatial coordinate points after the length of fault body extension is converted into a height value consistent with the length unit of the spatial coordinate points, and the length of fault body extension is determined by the ratio of the height value to the sine value corresponding to the dip parameter, and the length of fault body extension is degenerated into the height value when the sine value is zero; acquiring earthquake catalog data, and determining a plurality of earthquake points based on the earthquake catalog data, determining the spatial relationship between the earthquake points and the fault according to the three-dimensional fault surface geometric model and the fault body geometric model, and classifying the earthquake points into fault surface points located on the three-dimensional fault surface geometric model, fault body points located inside the fault body geometric model and fault points located outside the fault body geometric model, to identify fault-related tectonic earthquakes; outputting and exporting analysis results; the analysis results comprise a three-dimensional fault model composed of the three-dimensional fault surface geometric model and the fault body geometric model, an earthquake distribution map, an earthquake MT map, a b value, a profile along the fault strike direction and a profile perpendicular to the fault strike direction.

2. The method for automatically extracting and identifying relevant structure earthquakes under the constraint of three-dimensional geometry of faults according to claim 1, characterized in that, The method comprises: performing principal component analysis processing on the fault surface trace data to obtain a fault strike angle, comprising: performing data standardization processing on the spatial coordinate points; calculating the covariance matrix of the spatial coordinate points; performing eigenvalue decomposition on the covariance matrix to extract the principal component direction; calculating the strike angle based on the principal component direction; performing angle normalization processing on the strike angle to make the strike angle fall within the range of 0 to 360 degrees; 3. The method for automatically extracting and identifying relevant structure earthquakes under the constraint of three-dimensional geometry of faults according to claim 1, characterized in that, performing data quality checking to identify and exclude abnormal spatial coordinate points. The method comprises: generating two dip angle candidate values based on the strike angle using orthogonal vector decomposition processing, and receiving selection input of the dip angle candidate values to determine a dip angle, comprising: obtaining a first dip angle candidate value by adding ninety degrees to the strike angle, and obtaining a second dip angle candidate value by subtracting ninety degrees from the strike angle; performing angle normalization by 360 degrees on the first and second candidate values of the trend angle; performing geology rationality verification on the first and second candidate values of the trend angle; outputting a direction literal description of the first and second candidate values of the trend angle, and receiving the selection input to determine the trend angle.

4. The method for automatically extracting and identifying relevant structure earthquakes under the constraint of three-dimensional geometry of faults according to claim 1, characterized in that, generating a three-dimensional fault surface geometric model by NURBS surface modeling, including: generating a control point grid according to the spatial coordinate points, the strike angle, the trend angle, and the dip angle parameter; setting the number of NURBS surface in U direction and V direction; creating NURBS surface and loading the control point grid; performing surface refinement and optimization processing on the NURBS surface to obtain the three-dimensional fault surface geometric model.

5. The method for automatically extracting and identifying relevant structure earthquakes under the constraint of three-dimensional geometry of faults according to claim 1, characterized in that, The steps of generating the fault body geometric model include: extending the three-dimensional fault surface geometric model along the trend direction under the extension length constraint; offsetting the three-dimensional fault surface geometric model along the normal direction according to the thickness parameter to form a fault body boundary; closing the fault body boundary to form the fault body geometric model; generating a triangular mesh representation of the fault body geometric model.

6. The method for automatically extracting and identifying relevant structure earthquakes under the constraint of three-dimensional geometry of faults according to claim 1, characterized in that, The extension length is determined by the ratio of the height value converted from the vertical height parameter to the same length unit as the spatial coordinate points to the sine value corresponding to the dip angle parameter, including: When the spatial coordinate points use meters as the length unit, the vertical height parameter in kilometers is converted to the height value in meters; When the spatial coordinate points use kilometers as the length unit, the vertical height parameter is kept as the height value.

7. The method for automatically extracting and identifying relevant structure earthquakes under the constraint of three-dimensional geometry of faults according to claim 1, characterized in that, Obtaining earthquake catalog data, and determining a plurality of earthquake points based on the earthquake catalog data, determining the spatial relationship between the earthquake points and the fault according to the three-dimensional fault surface geometric model and the fault body geometric model, and classifying the earthquake points into fault surface points located on the three-dimensional fault surface geometric model, fault body points located inside the fault body geometric model, and fault points located outside the fault body geometric model, including: automatically loading the earthquake catalog data and supporting CSV format and TXT format; obtaining a plurality of earthquake points based on the earthquake catalog data; generating a classification label for each earthquake point; the classification label is a fault surface point, a fault body point, or a fault point; exporting a CSV file containing the earthquake points and the classification labels, and generating an earthquake distribution statistical report.

8. The method for automatically extracting and identifying relevant structure earthquakes under the constraint of three-dimensional geometry of faults according to claim 1, characterized in that, Outputting and exporting analysis results, including: generating a top view mode earthquake distribution map, an oblique view mode earthquake distribution map, and a perspective view mode earthquake distribution map; generating the fault strike profile and the profile perpendicular to the fault strike; superimposing geological occurrence annotation information in the earthquake distribution map and the profile; exporting the earthquake distribution map and the profile.

9. The method for automatically extracting and identifying relevant structure earthquakes under the constraint of three-dimensional geometry of faults according to claim 1, characterized in that, Outputting and exporting analysis results also include: When the fault surface trace data is expressed in latitude and longitude coordinates, the latitude and longitude coordinates are converted into local meter-based coordinates for display in the seismic distribution map and the profile and for deriving the analysis results containing the local meter-based coordinate information.

10. A system for automatically extracting and identifying relevant structural seismic under the constraint of three-dimensional geometry of faults, characterized in that, The method comprises: a fault trace data acquisition unit configured to acquire fault surface trace data, geological occurrence parameters, and three-dimensional geometric parameters, the fault surface trace data containing a plurality of spatial coordinate points arranged in sequence; a strike angle calculation unit configured to perform principal component analysis processing on the fault surface trace data to obtain a fault strike angle; a dip angle determination unit configured to generate two dip angle candidate values based on the strike angle using orthogonal vector decomposition processing and receive a selection input of the dip angle candidate values to determine a dip angle; wherein the two dip angle candidate values differ by 180 degrees and are both perpendicular to the fault strike direction determined by the strike angle; a fault surface geometric modeling unit configured to generate a three-dimensional fault surface geometric model using NURBS surface modeling based on the strike angle, the dip angle, and a dip parameter in the geological occurrence parameters; a fault body geometric construction unit configured to determine a length of fault body extension along the dip direction based on a vertical height parameter, a thickness parameter, and the dip parameter in the three-dimensional geometric parameters, and to extend the three-dimensional fault surface geometric model along the dip direction determined by the dip angle under the constraint of the length of fault body extension, and to offset the three-dimensional fault surface geometric model along the normal direction of the three-dimensional fault surface geometric model according to the thickness parameter, to generate a fault body geometric model; wherein the length of fault body extension is converted into a height value consistent with the length unit of the spatial coordinate points after the vertical height parameter is converted, and the length of fault body extension is determined by the ratio of the height value to the sine value corresponding to the dip parameter, and the length of fault body extension is degenerated into the height value when the sine value is zero; a tectonic earthquake spatial determination unit configured to acquire earthquake catalog data and determine a plurality of earthquake points based on the earthquake catalog data, determine the spatial relationship between the earthquake points and the fault according to the three-dimensional fault surface geometric model and the fault body geometric model, classify the earthquake points into fault surface points located on the three-dimensional fault surface geometric model, fault body points located inside the fault body geometric model, and fault points located outside the fault body geometric model, to identify fault-related tectonic earthquakes; an analysis result generation and derivation unit configured to output and derive analysis results; the analysis results include a three-dimensional fault model composed of the three-dimensional fault surface geometric model and the fault body geometric model, a seismic distribution map, a seismic MT map, a b value, a profile along the fault strike, and a profile perpendicular to the fault strike.

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