基于变差函数的插值方法计算华北地区重力场变化

定点重复重力测量是获取区域重力场变化的主要手段之一, 重力场特征与地形起伏、 构造走向等因素相关。 以华北地区为例, 考虑区域内地形和构造的北东向分布规律, 从EGM2008重力模型中拟合各向异性变差函数参数, 利用变差函数网格化插值, 对华北地区2009—2013年期间重力场观测数据进行网格化重建, 获取华北地区重力场时空变化结果。 研究结果表明基于区域地形、 构造特征的各向异性变差函数插值方法, 获得的空间重力场变化在重力异常梯级带上更加明显, 重力变化与活动构造分布具有更好的一致性。 本文研究方法对于恢复区域时空重力场异常具有重要意义, 有助于提高应用重力资料划分潜在地震危险区空间位置的精度, 为华北地区震情研判和构建地震预报定量指标体系提供可靠的地球物理场数据。

Calculation of Gravity Variations in North China based on Kriging Gridding with Variogram Approach

Fixed-point gravity repeat measurement is one of the main approaches to get regional gravity changes. Regional gravity field is related to topographic relief, structural faults direction and other factors. We took north China as an example, considering regularity of topographic relief and structural faults with the north-east direction (NE), then fitted the anisotropic parameters of variogram based on EGM2008 gravity model. After that,we rebuilt the gravity variation field with the observations from 2009 to 2013 in north China by anisotropic variogram in Kriging gridding, for further studying temporal and spatial gravity variations in northern China. The results show that there are obvious temporal and spatial gravity variations, especially in gravity anomaly gradient belt through the variogram approach, which is based on regional topography and structure characteristics. Besides, the gravity anomaly field had a better consistency with the distribution of tectonic faults, which could provide the geophysical basis for seismic risk analysis in north China.