陕西泾阳4.8级地震前后重力变化与断裂活动

本文对泾阳Ms4．8级地震前后陕西关中地区流动重力观测资料和有关断裂垂直形变资料进行了分析研究。结果表明：①波速比高值区很可能存在地下深部地幔物质的入侵，由此引发地震和重力场的显著下降；②用震源机制解和GPS所作的运动矢量图可以较好地解释泾阳地震前后重力场时空演化特征及有关断裂活动——其变化是北西向剪切应力带作用的结果．

Gravity Variation and Fault Activity before and after the Jingyang Ms4.8 Earthquake in Shaanxi Province

The mobile gravity data and fault vertical deformation data before and after the Jingyang Ms4.8 earthquake in Guanzhong region of Shaanxi province are systematically analyzed. According to the results we have the following understanding. First, the high zone of VP/VS ratio may reflect deep mantle material invasion which may conduce the earthquake and result in obvious gravity field decrease. Second, the characteristics of gravity field spatio-temporal variation and fault activity before and after the earthquake due to the effect of NW shear stress field can be explained by the focal mechanism solution and vector diagram of ground movement obtained by GPS measurement.