河北地区2015~2020年重力场动态变化特征

Dynamic Variation Characteristics of Gravity Field in Hebei Area from 2015 to 2020

基于河北及邻区2015~2020年流动重力测网12期观测资料,采用绝对控制下平差算法,得到河北地区重力场动态变化图像,并采用多项式拟合法计算重力场平均年变率。结果显示,重力场动态变化呈现明显的分区特征,西北部区域变化平稳,范围为-40~30μGal;东南部区域2015~2016年存在微弱的正值累积并持续向北东方向扩散,至2020年在天津-邯郸一线形成NE-SW向的椭圆形显著异常区,异常区北至燕山,西至太行山,正负差异最高达120μGal,平均年变率高值明显。结合区域内部分水位数据及地表沉降数据推测,东南部重力场高值区主要为地表沉降的结果,地下水影响相对被覆盖。

Using the relative gravity observation data of Hebei and surrounding areas from 2015 to 2020, we obtain the dynamic variation of the gravity field. With the polynomial fitting method to calculate annual variability, we also analyze the characteristics of the gravity field changes in Hebei. The results show that the dynamic gravity change presents obvious regional characteristics. The gravity variation is stable in the northwest, within-40~30 μGal;while in the southeast there exists a slight positive accumulation from 2015 to 2016, which spreads to the northeast, forming a NE-SW elliptical anomaly between the Tianjin-Handan area in 2020. The anomaly ranges from Yanshan in the north to Taihang mountain in the west, with a maximum difference of 120 μGal, also with a high average change rate. Combined with the water level and surface subsidence data, the gravity variation in the southeastern high-value area is mostly caused by surface subsidence, the influence of groundwater loss is covered relatively.