Slip Distribution Inversion Of 2017 Halabja Earthquake Based On The InSAR Coseismic Deformation

In geological disasters,earthquakes are extremely destructive.Once it break out,there will be large-scale casualties and surface damage,which has seriously affected human life and economic development.In this regard,many seismologists actively devoted themselves to the study,anditfinally has been found that the occurrence of earthquakes is closely related to fault activity.Therefore,it is of great significance to study the movement characteristics of seismogenic faults based on the surface deformation caused by earthquakes for predicting earthquakes and reducing disaster losses.Synthetic Aperture Radar Interferometry?InSAR?,as a new Earth observation technology,is more suitable for monitoring surface deformation than traditional geodetic surveys because of its high resolution and all-day observation.However,synthetic aperture radar interferometry?SAR?acquires the line-of-sight deformation field,It is necessary to combine the image data of two different perspectives to accurately determine the deformation characteristics of the earthquake and constrain the subsequent inversion estimation.Taking the Halabja earthquake in 2017 as an example,the coseismic deformation field of the earthquake is extracted by D-InSAR technology,and the slip distribution inversion of faults is carried out based on Okada dislocation model.The following are the main contents and conclusions of this paper:?1?Using GAMMA software as the data processing platform,two pairs of ascending and descending Sentinel-1A image data are processed by two-pass differential interferometry,and the line-of-sight co-seismic deformation fields of ascending and descending data are obtained respectively.The results show that the deformation fields are concentrated in the main front fault of Zagros.The northeast part of the deformation field is mainly subsidence,the maximum line-of-sight deformation value is-37cm,and the southwest part is uplifted.The maximum line-of-sight deformation value is 88 cm,which shows uplift state on the whole and conforms to the deformation characteristics of thrusting earthquakes.?2?Establishing a single fault model with reference to the USGS fault parameters,The fault slip distribution of the Halabja earthquake is calculated based on the Okada elastic half-space dislocation modelwith the constraints of ascending and descendingorbital deformation data after uniform down-sampling and quadtree down-sampling.By comparing the fitting residuals and slip distributions of the two sampling data,it is considered that the quadtree down-sampling deformation data can better constrain faults.Therefore,the inversion results based on quadtree downsampling data are chosen as the final result of this paper.?3?The inversion results show that the Halabja earthquake is thrusting fault,and theseismogenicfault is mainly characterized by thrusting movement with right-lateral strike-slip movement.The slip distribution is mainly concentrated in the area along the strike of 0 to 45 km and along the dip of 10 to 40 km.The maximum sliding amount is3.29m and the maximum energy released by the earthquake is 1.12×10²⁰ N·m?M_W=7.33?.?4?According to the location of main and aftershocks,the distribution of deformation field and the slip characteristics of faults,the seismogenic fault is judged to be the main front fault of Zagros,which is consistent with the existing research results.