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CN-122017990-A - Fracture locking rate inversion method based on GNSS crust deformation observation and elastic dislocation theory constraint

CN122017990ACN 122017990 ACN122017990 ACN 122017990ACN-122017990-A

Abstract

The invention provides a fracture locking rate inversion method based on GNSS crust deformation observation and elastic dislocation theory constraint, which comprises the steps of constructing a fracture three-dimensional model and an elastic dislocation constraint model, calculating the fracture locking rate, and identifying a pregnant earthquake high risk area through multi-period result comparison, strain field verification and earthquake activity verification. According to the invention, a GNSS crust deformation observation elastic dislocation theory is adopted to restrict a negative dislocation model, so that the accuracy and stability of fracture locking rate inversion are obviously improved. The invention integrates multi-period GNSS data to realize dynamic inversion and can capture the evolution trend of the locking state. According to the invention, secondary blocks are finely divided, strain rate field constraint is introduced, the locking distribution of a local strain enhancement region is accurately identified, the reliability of judging a major earthquake risk region is improved, and a broken high locking rate region is definitely broken.

Inventors

  • ZHANG NAN
  • WANG JING
  • WANG JING
  • LIANG SHIMING
  • YUAN XIAOXIANG

Assignees

  • 宁夏回族自治区地震局

Dates

Publication Date
20260512
Application Date
20260215

Claims (10)

  1. 1. The fracture locking rate inversion method based on GNSS crust deformation observation and elastic dislocation theory constraint is characterized by comprising the following steps of: Acquiring GNSS observation data, namely acquiring multi-period observation data of a GNSS reference station and a mobile station of a target area covered by a national continental construction environment monitoring network, wherein the target area is a north-south seismic zone north section of 32-43 DEG N and 95-112 DEG E; The data preprocessing of the step (2) is to perform rough difference elimination based on space-time correlation on GNSS observation data, and perform high-precision atmospheric delay correction by combining a global atmosphere grid model and regional vapor radiation data; The GNSS velocity field calculation in the step (3) is to adopt MIT open source software GAMIT/GLOBK to calculate clean observation data and construct a multi-period GNSS velocity field under a unified reference frame (European and Asian plate stable frame); Step (4) fracture three-dimensional geometric modeling, namely establishing a three-dimensional geometric model of main movable fracture of a target area based on geological survey results and former research data, and determining the spatial distribution of fracture trend, tendency, inclination angle and 0-30 km depth; The elastic dislocation constraint model construction method comprises the steps of (5) equivalent breaking locking segments to rectangular negative dislocation units embedded in an elastic half-space medium, establishing a Green function response matrix between breaking negative dislocation slip loss and earth surface GNSS deformation rate, introducing a double physical constraint mechanism based on the construction of the elastic dislocation constraint model, wherein the secondary block internal strain rate tensor calculated based on a block dynamics model is used as a priori constraint to ensure that inversion results accord with regional construction stress fields; step (6) regularization inversion of fracture parameters, namely adopting a self-adaptive Tikhonov regularization method, automatically adjusting regularization factors according to geometric complexity of fracture segments, solving inversion equations with constraints, and synchronously calculating long-term sliding rate, co-vibration sliding quantity and post-vibration viscoelastic relaxation rate of each fracture sub-segment to obtain accurate fracture sliding loss rate; step (7) quantitative calculation of fracture locking rate, namely calculating the locking rate of each fracture segment according to the ratio of the fracture slip loss rate to the long-term slip rate, and obtaining the fracture slip loss rate based on inversion Fracture long-term slip rate estimated in conjunction with geologic/geodetic measurements According to the formula Calculating the locking rate of each sub-segment, and introducing an uncertainty propagation model to quantify a locking rate confidence interval; And (8) verifying the result and identifying the risk, namely confirming the reliability of the inversion result through multi-period GNSS speed field time sequence collaborative verification, inSAR deformation rate field cross verification and historical strong earthquake recurrence period matching analysis, and identifying a large earthquake high risk pregnant earthquake region by combining the three-dimensional distribution of fracture locking rate and coulomb stress loading rate.
  2. 2. The method of claim 1, wherein the multi-phase observation data in step (1) comprises 1998-2018 continuous observation data, and 10 sub-phase data of 1999-2001, 2001-2004, 15-2015, 2015-2020.
  3. 3. The method for inverting the breaking locking rate based on GNSS crust deformation observation and elastic dislocation theory constraint according to claim 1, wherein the GNSS velocity field precision obtained by the calculation in the step (3) is better than 0.5mm/a, and meanwhile, 18 baseline length time sequences and 5 profile velocity projection data of the cross-active breaking are extracted.
  4. 4. The method of claim 1, wherein the primary active fractures in step (4) comprise an alr Jin Beiyuan fracture, a hollanded foot fracture, a zhuanlang river fracture, a west Qinling the northern fringe fracture, an eastern kunlun fracture, a sea source fracture, a six-discal mountain fracture, and a qian mountain northbound fracture.
  5. 5. The method for inverting the breaking locking rate based on GNSS crust deformation observation and elastic dislocation theory constraint according to claim 1, wherein the response relation in the step (5) is characterized by an elastic dislocation green function matrix, and the formula is that Wherein For a GNSS observation velocity field vector, Is a green function matrix, and d is a sliding parameter vector.
  6. 6. The method of inverting the fracture closure under the constraint of GNSS crustal deformation observation and elastic dislocation theory according to claim 1, wherein the regularized inversion equation in step (6) is Wherein For regularization parameters determined by an L-curve method, the value is 0.01, and L is a smooth matrix.
  7. 7. The method for inverting the breaking locking rate based on GNSS crust deformation observation and elastic dislocation theory constraint according to claim 1, wherein the locking rate calculation formula in the step (7) is as follows Wherein For the break closure rate, D is the break slip loss rate (mm/a), To break the long-term slip rate (mm/a), The value range is 0-100%.
  8. 8. The method of claim 1, wherein the multi-phase result comparison in step (8) comprises calculating the slip loss rate variation of fractures at 2015-2020 and 2013-2015, and the collaborative verification of strain rate fields comprises correlation analysis of main strain rate field, maximum shear strain rate field and surface strain field.
  9. 9. The method for inverting the breaking closure rate based on GNSS crust deformation observation and elastic dislocation theory constraint according to claim 1, wherein in the step (4), when the breaking three-dimensional geometric modeling is performed, each breaking is divided into subsections with the length of 5-10 km, and the subsection division precision is matched with the GNSS site distribution density.
  10. 10. The method for inverting the fracture locking rate based on GNSS crust deformation observation and elastic dislocation theory constraint of claim 1, wherein the high-risk area of large earthquake in step (8) comprises 12 areas with locking rate higher than 70% such as an alr Jin Beiyuan fracture north wide beach mountain section, a zhuanlang river fracture Yongdeng county lanzhou junction section, a west Qinling the northern fringe fracture Tianshui section and a a married couple section.

Description

Fracture locking rate inversion method based on GNSS crust deformation observation and elastic dislocation theory constraint Technical Field The invention relates to the technical field of seismic monitoring and crust deformation analysis, in particular to a fracture locking rate inversion method based on GNSS crust deformation observation and elastic dislocation theory constraint. Background The fracture locking state is a core index for evaluating regional earthquake risk, and the slip defect accumulation of the fracture locking section is directly related to the occurrence possibility of major earthquake with stress concentration. The blocking feature monitoring of the main activity fracture of the north-south seismic zone has important significance for earthquake disaster early warning. The existing fracture locking rate inversion method is dependent on GNSS speed field data constraint of single period, lacks strict constraint of elastic dislocation theory, and is insufficient in stability and precision of inversion results, meanwhile, sliding parameters of different periods are insufficient in comparison and analysis, and dynamic evolution characteristics of locking states are difficult to capture. In addition, the traditional method is not fine enough to divide the secondary blocks, can not accurately reflect the locking distribution rule of the local strain enhancement region, and restricts the reliability of seismic risk assessment. The continental construction environment monitoring network of China accumulates long-term continuous GNSS observation data, and provides a high-precision data source for monitoring the deformation of the crust. How to construct a scientific inversion model based on the data constraint and combining with an elastic dislocation theory to realize the dynamic and high-precision inversion of the fracture locking rate becomes a technical problem to be solved in the current seismic monitoring field. Therefore, a fracture closure rate inversion method based on GNSS crust deformation observation and elastic dislocation theory constraint is proposed. Disclosure of Invention The invention aims to realize high-precision inversion of fracture sliding speed, sliding loss and locking rate by integrating multi-period GNSS speed field data constraint and utilizing a negative dislocation model and an elastic dislocation theory (note that the negative dislocation model and the elastic dislocation theory are two expressions of the same thing in a certain sense, and meanwhile, reveal dynamic evolution characteristics of the locking state, thereby providing reliable basis for seismic risk assessment. In order to achieve the aim of the invention, the invention provides the following technical scheme that the fracture locking rate inversion method based on GNSS crust deformation observation and elastic dislocation theory constraint comprises the following steps: Acquiring GNSS observation data, namely acquiring multi-period observation data of a GNSS reference station and a mobile station of a target area covered by a national continental construction environment monitoring network, wherein the target area is a north-south seismic zone north section of 32-43 DEG N and 95-112 DEG E; The data preprocessing of the step (2) is to perform rough difference elimination based on space-time correlation on GNSS observation data, and perform high-precision atmospheric delay correction by combining a global atmosphere grid model and regional vapor radiation data; The GNSS velocity field calculation step (3) is to adopt MIT open source software GAMIT/GLOBK to calculate clean observation data and construct a multi-period GNSS crust movement velocity field under a unified reference frame (European and Asia plate stable frame); Step (4) fracture three-dimensional geometric modeling, namely establishing a three-dimensional geometric model of main movable fracture of a target area based on geological survey results and former research data, and determining the spatial distribution of fracture trend, tendency, inclination angle and 0-30 km depth; The elastic dislocation constraint model construction method comprises the steps of (5) equivalent breaking locking segments to rectangular negative dislocation units embedded in an elastic half-space medium, establishing a Green function response matrix between breaking negative dislocation slip loss and earth surface GNSS deformation rate, introducing a double physical constraint mechanism based on the construction of the elastic dislocation constraint model, wherein the secondary block internal strain rate tensor calculated based on a block dynamics model is used as a priori constraint to ensure that inversion results accord with regional construction stress fields; step (6) regularization inversion of fracture parameters, namely adopting a self-adaptive Tikhonov regularization method, automatically adjusting regularization factors according to geometric complexity o