陕西地区震源参数和平均应力场的研究

利用陕西地区地震台网记录的小震垂直分量最大振幅比测定了陕西地区的震源参数，并用其小震断层面解反演了平均应力场。结果表明，陕西地区最大主压应力方向为北东东向，倾角中等，相对中等主压应力较大，小震断层面呈北西和北东向优势分布。分区试验表明，关中地区与全省基本一致，陕南似乎存在较大差异，其最大主压应力方向为北北西一南南东方向，中等主压应力也相对较小。

RESEARCH ON THE PARAMETERS OF EARTHQUAKE FOCUSAND THE MEAN STRESS-FIELD IN SHANXI AREA

The parameters of earthquake focus in Shanxi area have been determined with the ratio be-tween the largest amplitudes of P and S which are the vertical components of the small earth-quakes recorded by the seismologic network in Shanxi area. And a mean stress-field was calculat-ed with the fault-plane solutions of small earthqukes.The results make know that the direction of the largest compressive principal-stress in Shaixi area is on northeast-east,the angle of inclina-tion is mean,the compressive principalstress relative to mean is bigger and the fault-planes of small earthquakese appera the superiority distribution on northweast and northeast. We tested with the method of dividing region. The results make knos that the stress state in the central Shanxi plain is in keeping with that of all province and that it looks as if the state of stress in the south shanxi is more different,the direction of the largest compressive principal-stress is on north northweast to south southeast and the mean compressive principal-stress also is smaller relatively.