Using plane dislocation theory and the seismic-wave inversion results from the Institute of Geophysics, China Earthquake Administration and the Institute of Geodesy and Geophysics, Chinese Academy of Sciences models, ...Using plane dislocation theory and the seismic-wave inversion results from the Institute of Geophysics, China Earthquake Administration and the Institute of Geodesy and Geophysics, Chinese Academy of Sciences models, the surface coseismic deformation and gravity changes caused by the 2013 Ms7.0 Lushan earthquake are simulated. The simulations of coseismic gravity change and deformation indicate that the dislocation has dip-slip characteristics. The results also show that the coseismic deformation exhibits a symmetrical, positive-and-negative distribution, with the deformation usually being less than 10 mm in the far- field but up to 140 mm in the near-field. The gravity changes are concentrated on the fault-projection area, which is greatly affected by the vertical surface deformation. The gravity change and vertical deformation in the far field are usually less than and 5 mm, respectively, but reach and 330 mm, respectively, in the near field. The simulated results agree well with the measured resuhs, which suggests a theoretical basis for the observed change in gravity before and after this earthquake.展开更多
The November 14,2001 M_S8.1 Kunlun Mountains earthquake in northern Tibet is the largest earthquake occurring on the Chinese mainland since 1950.We apply a three-dimensional(3-D)finite element numerical procedure to m...The November 14,2001 M_S8.1 Kunlun Mountains earthquake in northern Tibet is the largest earthquake occurring on the Chinese mainland since 1950.We apply a three-dimensional(3-D)finite element numerical procedure to model the coseismic displacement and stress fields of the earthquake based on field investigations.We then further investigate the stress interaction between the M_S8.1 earthquake and the intensive aftershocks.Our primary calculation shows that the coseismic displacement field is centralized around the east Kunlun fault zone.And the attenuation of coseismic displacements on the south side of Kunlun fault zone is larger than that on the north side.The calculated coseismic stress field also indicates that the calculated maximal shear stress field is centralized around the east Kunlun fault zone;the directions of the coseismic major principal stress are opposite to that of the background crustal stress field of the Qinghai-Xizang(Tibet)Plateau.It indicates that the earthquake relaxes the crustal stress state in the Qinghai-Xizang(Tibet)Plateau.Finally,we study the stress interaction between M_S8.1 earthquake and its intensive aftershocks.The calculated Coulomb stress changes of the M_S8.1 great earthquake are in favor of triggering 4 aftershocks.展开更多
Using the results of aftershock relocation, inversion on seismic waves and InSAR results, and surface rupture displacements obtained by geological survey after the earthquake, this paper constructs a fault model of th...Using the results of aftershock relocation, inversion on seismic waves and InSAR results, and surface rupture displacements obtained by geological survey after the earthquake, this paper constructs a fault model of the Yushu Ms7. 1 earthquake. Based on rectangular dislocation theory in an elastic-viscoelastic layered medium, we have simulated the co- seismic deformation and gravity change with gravitational effect considered. The pictures show that the absolute gravity measuring point is beside the extremum of coseismic gravity change, and the numerical value reaches 25.02 x 10-Sm. s-2. After a discussion about the gravity changes before the earthquake and the coherence consistency between two FG-5 absolute gravimeters, we think that the measured value 27.2 × 10^-8 m· s^-2 at Yushu station is coseismic gravity change. It＇s coincident with the simulation results based on dislocation theory. Therefore it is a good tool to test the near-field changes found by dislocation theory.展开更多
基金supported by the National Natural Science Foundation of China(41104049)the Seismic Industry Research Project(201008001)the Earthquake Tracking Task of China Earthquake Administration(2013020211)
文摘Using plane dislocation theory and the seismic-wave inversion results from the Institute of Geophysics, China Earthquake Administration and the Institute of Geodesy and Geophysics, Chinese Academy of Sciences models, the surface coseismic deformation and gravity changes caused by the 2013 Ms7.0 Lushan earthquake are simulated. The simulations of coseismic gravity change and deformation indicate that the dislocation has dip-slip characteristics. The results also show that the coseismic deformation exhibits a symmetrical, positive-and-negative distribution, with the deformation usually being less than 10 mm in the far- field but up to 140 mm in the near-field. The gravity changes are concentrated on the fault-projection area, which is greatly affected by the vertical surface deformation. The gravity change and vertical deformation in the far field are usually less than and 5 mm, respectively, but reach and 330 mm, respectively, in the near field. The simulated results agree well with the measured resuhs, which suggests a theoretical basis for the observed change in gravity before and after this earthquake.
基金The research was sponsored by the"Basic Scientific Research Plan"(02076902-03) of Institute of Earthquake Science, China Earthquake Administrationby grants from the Chinese Ministry of Science and Technology (2004CB418406, 2005DKA64000).
文摘The November 14,2001 M_S8.1 Kunlun Mountains earthquake in northern Tibet is the largest earthquake occurring on the Chinese mainland since 1950.We apply a three-dimensional(3-D)finite element numerical procedure to model the coseismic displacement and stress fields of the earthquake based on field investigations.We then further investigate the stress interaction between the M_S8.1 earthquake and the intensive aftershocks.Our primary calculation shows that the coseismic displacement field is centralized around the east Kunlun fault zone.And the attenuation of coseismic displacements on the south side of Kunlun fault zone is larger than that on the north side.The calculated coseismic stress field also indicates that the calculated maximal shear stress field is centralized around the east Kunlun fault zone;the directions of the coseismic major principal stress are opposite to that of the background crustal stress field of the Qinghai-Xizang(Tibet)Plateau.It indicates that the earthquake relaxes the crustal stress state in the Qinghai-Xizang(Tibet)Plateau.Finally,we study the stress interaction between M_S8.1 earthquake and its intensive aftershocks.The calculated Coulomb stress changes of the M_S8.1 great earthquake are in favor of triggering 4 aftershocks.
基金funded by the National Natural Science Foundation of China(41104049)the Earthquake Situation Tracking,CEA(2012020207)Scientific Investigation of Yushu M S 7.1 Earthquake,CEA(2060302)
文摘Using the results of aftershock relocation, inversion on seismic waves and InSAR results, and surface rupture displacements obtained by geological survey after the earthquake, this paper constructs a fault model of the Yushu Ms7. 1 earthquake. Based on rectangular dislocation theory in an elastic-viscoelastic layered medium, we have simulated the co- seismic deformation and gravity change with gravitational effect considered. The pictures show that the absolute gravity measuring point is beside the extremum of coseismic gravity change, and the numerical value reaches 25.02 x 10-Sm. s-2. After a discussion about the gravity changes before the earthquake and the coherence consistency between two FG-5 absolute gravimeters, we think that the measured value 27.2 × 10^-8 m· s^-2 at Yushu station is coseismic gravity change. It＇s coincident with the simulation results based on dislocation theory. Therefore it is a good tool to test the near-field changes found by dislocation theory.
