兰州—天水—武都地区重力场变化及其与地震的关系

CHANGE OF GRAVITY FIELD AND RELATIONSHIP BETWEEN IT AND EARTHQUAKE IN LANZHOU—TIANSHUI—WUDU AREA

应用流动重力观测资料，研究分析了南北地震带北段兰州—天水—武都地区重力场的时空变化特征．结果表明，以１０５° Ｅ 为界，其东西二侧重力场变化明显不同．据此判断，沿１０５° Ｅ 在地壳的深部存在一条 Ｎ Ｓ 向活动构造．１９９０ 年以来在甘肃省境内发生的３ 次５ 级以上地震前，兰州岸门村和永登树屏２

Using data of mobile gravity measurement,variation features of gravity field in south area of northern segment of the North south seismic belt is analysed.The results show that using 105°E as a boundary,gravity field variation of the east side of the boundary is different from that of the west side of the boundary,reflecting there is a NS active tectonic zone in deep crust along 105°E.In Gansu province,three M S≥5 earthquakes occurred since 1990.Before the three earthquakes,anomalies of gravity differences of Anmencun,Lanzhou and Shuping,Yongdeng observation sites are obvious.