| Interferometric Synthetic Aperture Radar(InSAR)is a new geodetic technology,which is capable of acquiring high-precision surface deformation information after more than 20 years of rapid development.It has been widely used in the deformation monitoring of different periods in the earthquake cycle with the advantages of high spatial resolution,wide coverage,day-and-night monitoring and weather resistance.Based on DInSAR and time series InSAR technique,we take the 2015 Nepal Mw7.8 earthquake and the Haiyuan fault zone as the research object,and carrie out the coseismic,interseismic deformation observation and kinematics inversion.The main research contents and conclusions of this paper are as follows:1.The S1 A and ALOS-2 satellite ascending and desecending InSAR data were used to obtain the LOS coseismic displacement field of the Mw7.8 earthquake in Nepal,and the coseismic deformation fields were compared in detail.The fault slip distribution was inverted using different data combinations,and the difference between inversion results constrained by the single platform data and multi-platform data was compared.Using the synthetic north-south deformation field combined with the ascending S1 A and the desecending ALOS-2 LOS coseismic deformation field,considering the change of the incident angle,the three-dimensional deformation component of the earthquake is calculated.The results show that the earthquake was dominated by vertical and southward deformation.Vertical deformation from north to south included an area of subsidence on the trailing edge and an area of uplift on the leading edge.The maximum values of the uplift and subsidence were 1.5 and 1.0 m,respectively.North–south deformation showed overall southward movement with maximum displacement of more than 1.5 m.East–west deformation presented a four-quadrant distribution with maximum displacement of ~0.6 m.Composite thrusting movement occurred on the upper part of the seismogenic fault;overall,there was southward push motion and wave-shaped fold motion.2.Using the 2003-2010 Evisat/ASAR long-strip data,based on the StaMPS time series processing technique,the InSAR LOS average deformation rate field of the Jinqianghe segment to the 1920 earthquake rupture segments was obtained.There is a significant difference between the deformation rate field in the north and south wall,which is consistent with the motion characteristics of the left-lateral strike-slip in the Haiyuan fault zone.Through the analysis of the high-density cross-fault deformation rate profile of the Laohushan segment,it is determined that the creep length is about 19 km.Based on the two-dimensional arctan model,the deformation rate profile of InSAR is fitted,and the fault depth and deep slip velocity of different segments in the Haiyuan fault zone are obtained.The results show that the slip rate of the Laohusahn segment decreases from west to east,from 7.6 mm/a in the west to 4.5 mm/a in the easternmost part;the western and middle parts are in a locked state,and the depth of the western part is 4.2~4.4 km,the middien is 6.9 km,while the eastern is less than 1 km,that is,the shallow surface is creeping,and the creep rate is 4.5~4.8 mm/a.The 1920 rupture segments are in a locked state,and the slip rate and the locking depth gradually increased from west to east.The slip rate increased from 3.2 mm/a in the western segment to 5.4 mm/a in the eastern segment,and the blocking depth was from the west segment 4.8 km increased to 7.5 km in the eastern segment.3.Based on the three-dimensional negative dislocation block model,using different density GPS data and their combination with InSAR data for the inversion,the fault locking degree,the long-term relative slip rate between blocks and the distribution of slip rate deficit are obtained,and the comparative analysis is carried out.The main understandings are as follows:(1)The addition of encrypted GPS data can provide better constrain for fault kinematic parameters.The addition of InSAR data significantly improved the inversion results.(2)The locking depth is about 17 km in the Lenglongling segment,and it gradually decreases eastward to the near surface of the middle part of the Laohushan segment.And that in the middle and east sections of the rupture section is in the range of 3 to 7 km.while that of near-surface in the eastern part of the Laohushan and the 1920 rupture segments are weak.(3)The long-term left-lateral strike-slip rate between the plates on both sides of the Haiyuan fault decreased from west to east from 4.7 mm/a in Lenglongling to 2.0 mm/a in the eastern segment of the 1920 rupture.(4)The slip rate deficit is mainly concentrated in the Jinqianghe segment and its west part.There is also a certain slip rate deficit in the near surface of Maomaoshan segment and Laohushan segment(excluding its eastern end)and there is no slip rate deficit in the 1920 rupture segment.. |
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