东北地区重力场动态变化特征与前郭5.8级震群关系研究

Study on the Relationship Between Recent Variation Characteristics of Gravity Field and the Qianguo M_S5.8 Earthquake Swarm in Northeast China

利用2010~2016年东北地区的流动重力观测数据,分析该地区区域重力场动态演化和2013年前郭5.8级震群前后的变化特征。结果表明,差分和累积重力变化整体呈北西向和近南北向,与北东和北北东向构造格局不一致,重力变化受构造控制作用较弱;近期整体重力变化较平缓,基本没有超过60μGal的梯级带,反映出地下构造活动和物质运移水平相对平稳;前郭5.8级震群和通辽5.3级地震震前存在明显的能量积累,有利于破裂的产生,震后震荡恢复调整的时间需2~3a甚至更长。

Using mobile gravity measurements from 2010 to 2016 in northeast China, we systematically analyze regional gravity field changes and variation characteristics of gravity before and after the 2013 Qianguo MS5.8 earthquake swarm. The results show that the inter-annual and dynamic changes of gravity present NW and near NS direction in the study area, which differs from the structural framework of NE and NNE direction. This suggests that the variation of gravity field is weak in structure control. Generally, gravity changes are relatively gentle in northeast China, with rarely more than 60 μGal gravity gradient zone. This phenomenon shows that the level of underground structural activity and material migration is relatively stable in an indirect way. There are obvious gravity variation characteristics during the process of the earthquake preparation before the Qianguo MS5.8 earthquake swarm and the Tongliao MS5.3 earthquake. These cause continuous accumulation of seismic energy and the occurrence of earthquake rupture. The shock recovery adjustment of the gravity field after the earthquakes will take three or more years.