2016年射阳M_S 4.4地震前后重力场变化
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摘要
利用江苏重力测网2014—2017年重力场观测资料,采用绝对重力控制与相对重力联测相结合的平差方法,获取2016年射阳M_S 4.4地震前后重力场变化图。根据射阳M_S 4.4地震前后射阳地区各测线重力段差变化特点,绘制重力场等值线并进行对比分析,结合相关机理,探讨重力场变化与该地震的内在联系。同震观测数据显示:射阳M_S 4.4地震发生在重力异常值高梯度带附近,发震时震中地区位于NS挤压正异常、EW张拉负异常状态,震后区域重力梯度变化量开始减小,是一种典型的重力异常调整现象。
Using the data of Jiangsu gravity survey network for 2014-2017 years, the gravity field change map is obtained by the adjustment method to combined absolute gravity control and relative gravity survey before and after Sheyang M_S 4.4 earthquake. According to the variation of the gravity difference between pre earthquake and post earthquake lines in Sheyang, the gravitational field contour map is given and contrasted and analyzed. The internal relation between the gravity field change and the M_S 4.4 earthquake in Sheyang is discussed in accordance with the relevant mechanism. The data of the same earthquake observation show that Sheyang M_S 4.4 earthquake occurred near the gravity anomaly high gradient zone, and the epicentral region was in the state of the North-South extrusion positive anomaly and the East-West tension and negative anomaly. The variation of the gravity gradient began to decrease after the earthquake, and it was a typical gravity anomaly adjustment phenomenon.
Using the data of Jiangsu gravity survey network for 2014-2017 years, the gravity field change map is obtained by the adjustment method to combined absolute gravity control and relative gravity survey before and after Sheyang M_S 4.4 earthquake. According to the variation of the gravity difference between pre earthquake and post earthquake lines in Sheyang, the gravitational field contour map is given and contrasted and analyzed. The internal relation between the gravity field change and the M_S 4.4 earthquake in Sheyang is discussed in accordance with the relevant mechanism. The data of the same earthquake observation show that Sheyang M_S 4.4 earthquake occurred near the gravity anomaly high gradient zone, and the epicentral region was in the state of the North-South extrusion positive anomaly and the East-West tension and negative anomaly. The variation of the gravity gradient began to decrease after the earthquake, and it was a typical gravity anomaly adjustment phenomenon.
引文
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国家地震局.地震重力测量规范[M].北京:地震出版社,1997.
陆汉鹏,李建奎,王锋吉,等.2013年莱州MS 4.6、2015年乳山MS 4.6级地震前后重力场变化特征[J].华南地震,2016,36(4):27-33.
周友华.布格异常及均衡异常物理意义的探讨[J].西北地震学报,1995,17(2):84-86.