2017年12月19日海城M4.4地震重力变化及机理研究

利用辽宁地区2013-2018年流动重力观测资料,分析研究2017年12月海城M4.4震前重力空间演化特征及变化机理。研究表明:(1)辽中南地区重力场异常变化与海城M4.4地震具有一定的时空对应性;(2)一年半的累积变化显示震中东北部呈正变化,西南部呈负变化,并伴有重力变化高梯度带,最大幅差达70μGal。邻期变化显示,震前半年出现大范围正负反转变化和四象限特征,幅值在40μGal左右;(3)0值线控制海岫地区并出现转折,海城河断裂附近出现差异的重力变化;(4)结合海岫地区地质构造背景,认为该次地震事件所反映出的重力变化可能是辽中南地区地壳构造运动和地壳深部物质迁移共同所致。

Study on the Variation and Mechanism of Gravity Before Haicheng M4.4 Earthquake on December 19,2017

Based on the data of flow gravity observation from 2011 to 2018 in southern liaoning province,analysis was carried out on the evolution characteristics and the mechanism of gravity space before the M4.4 Haicheng earthquake in December 2017.The study shows that:(1)There is a good correspondence in time and space between the anomaly of the gravity field with the M4.4 Hasicheng earthquake in Central and southern Liaoning;(2)Cumulative changes of one and a half years,the northeast part of the epicenter shows a positive change,and the southwest is negative,with a high gradient belt,the maximum gradient is 70μGal.Adjacent phase change show that,a large range of positive and negative reversals and four quadrant features appeared in the half a year before the earthquake,the amplitude is about 40μGal;(3)0 value lines control the Xiuyan region and have a turning point,on the Haicheng River fault threr is a variation of gravity;(4)Combined with the geological tectonic setting in the Hai-xiu region,it is believed that this earthquake may be a result of the density variation of the deep material and tectonic movement in the southern region of central and southern Liaoning.