| In 1958, Steketee introduced the dislocation theory into seismology, thus established the theoretical relationship between the surface coseismic displacement and fault. After nearly 30 years’development, semi-infinite homogeneous space dislocation theory is formed. However, the monitoring of active fault deformation is the foundation of fault-related research. In recent years, with rapid development and the precision improvement of GPS technology and terrestrial observations data can invert fault and coseismic slip, which has great significance for researches on seismogenic process, model and earthquake warning, thus it can drive the development of the high-precision GPS technology’s application and research on faults、 earthquakes and other aspects.This paper is mainly based on GPS monitoring data to get faults and surface activity information, conducted research on the two typical faults, the seismogenic fault of Japan earthquake and the non-seismogenic fault of Xianshuihe, and introduced PCAIM model to conduct related research to obtain useful conclusions. The main contents and results are summarized as follows:1. Use the GPS data of 70 sites of Japan’s "GEONET" network to calculate seismic displacement caused by the Japan earthquake. The results show:displacement on horizontal direction shows high consistency, almost all displacement is tower east, and the maximum horizontal displacement reaches up to 5.2m; the vertical displacement of the sites near the epicenter area in the eastern coastline are of large settlement, the maximum settlement reaches up to 0.9m. Based on ITRF2005 global reference frame, uses WN+FN noise model calculates the velocity field before and after the earthquake of these 70 sites, the results show:the moving speed and direction of all the sites have large change. The change of moving rate mainly shows in site J167、J170、J172, those sites are near the epicenter in the north-central of Honshu in the east of E138°,the moving direction of most sites changes from moving to southeast before earthquake to moving to east after the earthquake.2. According to GPS coordinate time series data, geometry of fault and rupture fault model, it calculates coseismic displacement field and dislocation distribution of this earthquake with PCAIM model. The result shows:inversion result is basic the same as calculation result, the residual average value of the three E、N、U directions are 3.2cm、6.2cm、7.7cm; the fault rupture mainly occurs in area that near the epicenter, of 50 to 150km area, the maximum slip value of the fault rupture is 27.3 m and the location is the area that near the epicenter and below 15 to 25km of the surface ground.3. Based on continuous observation data of GPS observation sites laid cross Xianshuihe fault and obtained baseline time series of every monitoring site with the GAMIT/GLOBK calculation. Under the assumption of the rigid block, through the projection, finally obtained of both sides of fault in Daofu and Qianning, that South-West plate relative to the North-East plate’s and in the overall movement feature and rate under ITRF2005 framework. The results shows:the slip of Daofu and Qianning are of strong left-strike slip rates; while Daofu showed weak tensional, Qianning is strong compared to Daofu. While overall movement also shows blocks relative movement direction on both sides of the fault from Daofu to Qianning appears larger angle deflection in clockwise. Through self-write ductile-brittle faults layered model inversion procedures, inversion of the study area conversion layer activity rate of each fault in recent years, and using these results, obtained the relative moving trace of both sides of the fault, the result is consistent with the observed result, which shows the feasibility of the model. PCAIM model analyzes the coordinates of 1.6 years after earthquake data. The results of the surface slip distribution in the inversion area shows:Two plates are larger in the ITRF2005 reference framework, South-West plate is 27.3mm, North-East plate is18.7mm. |
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