Observation of P-wave velocity anisotropy of the shallow crust in the northern Xiaojiang fault zone:Principle and numerical tests
Ma Qiyang
Xu Lisheng
Yan Chuan
Li Chunlai
Xu Kangsheng
Abstract：This paper proposes a new technique,residual slowness vector tech-nique (RST),for estimating anisotropy of the seismic velocity using the resi-duals of traveling times assuming that 2-D observed velocity field is taken as the superposition of anisotropic field and isotropic one.And then the technique is applied to P traveling time residuals of 3 181 events recorded by 24 stations of the Qiaojia Array,a mobile array of seismic broadband stations installed across the northern Xiaojiang fault zone.The residual slowness vectors are calculated within a scale of 0.5°×0.5°in the horizontal direction and 0—5 km in the verti-cal direction around the observation stations.Finally the polarization directions of the fast P-velocity and slow P-velocity are obtained at all the stations by using the RST.The results show that the directions of the P-velocity at most of the stations are in good agreement.The fast-P directions point to ESE,which near-ly agrees with the P axis direction of stress field in northern Xiaojiang fault zone,while the slow-P directions point to NNE,which nearly agrees with the T axis direction,implying that long period of stress action might be one of the important factors causing the P wave velocity anisotropy in this region.
Keywords：anisotropyP-wave velocitytravelling time residualnorthern Xiaojiang fault zone
Publication Date：2016-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：14( 15-28 )