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Study On Postseismic Deformaion Of The 2001 Kunlun Mountain Ms 8.1 Earthquake

Posted on:2018-09-28Degree:MasterType:Thesis
Country:ChinaCandidate:Y J WangFull Text:PDF
GTID:2370330515990506Subject:Geodesy and Survey Engineering
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In recent years,space geodesy has achieved rapid development with increasing observational stations and better observation technology.InSAR and GPS technology provides an effective means for crustal deformation monitoring and a new opportunity for further research of postseismic deformation.Afterslip of the fault and the viscoelastic relaxation of lower crust/upper mantle can be studied by the constraint of postseismic deformation.As a large strike-slip fault zone,the Kunlunshan fault zone has always been the significant window for researching the Qinghai Tibet Plateau.This earthquake provided a good opportunity for studying strike-slip movement.Deep research on this event can help us understand the present stress state and evolution history of Tibet Plateau,giving us further understanding of the dynamic environment of seismogenic zone.This study introduces the history and present situation of postseismic deformation research firstly,then the theories and methods of post earthquake research are systematically expounded.Postseismic afterslip and viscoelastic relaxation are the main mechanism for Kunlunshan earthquake.Both deformation fields are simulated simply by planar semi-analytical solution.The InSAR and GPS data were used to analyze the deformation mechanism of the Ms 8.1 Kunlunshan earthquake in 2001.In general,the paper mainly includes the following contents:Based on the InSAR observation of Ms 8.1 Kunlunshan earthquake in year 2-6deformation and GPS deformation observation as the constraint,in-depth study of the deformation mechanism is provided caused by the postseismic deformation,hoping to have a better understanding of the dynamic environment of kinematic properties and the area of the Kunlun fault.The viscoelastic relaxation of the lower crust and upper mantle mainly affects the surface displacement of the far field,while the post earthquake slip is the main factor affecting the near field.Research results are shown as follows:1)lower crust and upper mantle viscoelastic on far-field postseismic deformation has stronger binding;2)compared with the earthquake,afterslip has great influence on the deformation in the near field,and the influence on the whole deformation field is larger,resulting in the surface displacement tonsure smaller;postseismic viscoelastic relaxation model selected far field simulation of orbit T133D,the calculation results show that the regional crust optimal viscosity coefficient between1×1019Pa s.2 5×1019Pa s and the simulation results of upper mantle viscosity coefficient is not very sensitive,the optimal viscous coefficient in the upper mantle is between1×1019Pa s.6 3×1019Pa s 4)considering the effect of afterslip and viscoelastic relaxation,we can better explain the near field earthquake displacement observation.Comprehensive model reflects the maximum fault slip amount is 0.39 m,distributed in the coseismic rupture surface below.5)The GPS sites on the north and south side are simulated by the afterslip,postseismic viscoelastic relaxation and the integrated model.The results show that there are differences in viscosity coefficient between the north and south sides,while the viscosity coefficient on the north side is higher than that on the south side.In order to obtain better results,different rheological parameters should be used on both sides of the simulated data.The simulation results also reflect that the rheological structure of Kunlun Mountains area may change over time.There is non-linear relationship between equivalent viscous coefficient and strain rate.
Keywords/Search Tags:postseismic deformation, Kunlunshan earthquake, postseismic afterslip, postseismic viscoelastic relaxation
PDF Full Text Request
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