宁夏地区重力场变化与2012年永宁M_S4.6地震
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摘要
利用宁夏地区2011—2013年期间多期重力观测资料,采用中国地震局推广的LG-ADJ程序对观测资料进行平差处理,给出地震前后3年的区域重力场变化和点值变化图像。结合构造活动分析,对2012永宁4.6级地震前后宁夏地区重力异常变化进行研究。认为:2012年永宁地震前,测区重力场出现较好的中期前兆性变化图像,临震前短期异常突增,重力场在空间和量值上均出现大幅的上升变化,重力点值震前趋势下降-转折上升-加速上升-发震的变化,是非常值得关注的前兆异常。
In this paper,in combination with the analysis of tectonic activities in the Ningxia region,we use 2011—2013 gravity observation data to investigate the gravity anomaly variation before and after the 2012 Yongning M_S4.6 earthquake.We used LG-ADJ software to process the data,which has been generalized by the China Earthquake Administration.The research results show that the gravity field in the measurement area underwent good medium-term precursory variation before the 2012 Yongning M_S4.6 earthquake,after which the impending anomalies suddenly increased.The gravity field showed a sharp rise in both area and quantity.The variation tendency of the gravity point value before the earthquake showed a descent-ascent-accelerative ascent-earthquake occurrence style,which is an anomaly of widely recognized concern.
In this paper,in combination with the analysis of tectonic activities in the Ningxia region,we use 2011—2013 gravity observation data to investigate the gravity anomaly variation before and after the 2012 Yongning M_S4.6 earthquake.We used LG-ADJ software to process the data,which has been generalized by the China Earthquake Administration.The research results show that the gravity field in the measurement area underwent good medium-term precursory variation before the 2012 Yongning M_S4.6 earthquake,after which the impending anomalies suddenly increased.The gravity field showed a sharp rise in both area and quantity.The variation tendency of the gravity point value before the earthquake showed a descent-ascent-accelerative ascent-earthquake occurrence style,which is an anomaly of widely recognized concern.
引文
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[2]陈运泰,顾浩鼎,卢造勋,等.1975年海城地震与1976年唐山地震前后的重力变化[J].地震学报,1980,2(1):21-30.
[3]郝洪涛,李辉,张志坚.岷县-漳县6.6级地震前后重力场变化[J].大地测量与地球动力学,2014,34(3):43-46.
[4]申重阳,李辉,孙少安,等.2008年于田MS7.3地震前重力场动态变化特征分析[J].大地测量与地球动力学,2010,30(4):1-7.
[5]祝意青,梁伟锋,徐云马,等.汶川MS8.0地震前后的重力场动态变化[J].地震学报,2010,32(6):633-640.
[6]谢汝一,秦建增,冯建林,等.山西原平4.2级地震前的重力场异常特征[J].地震工程学2014,36(3):639-644.
[7]梁伟锋,赵云峰,徐云马,等.河西地区重力变化与2013年门源MS5.1地震研究[J].地震工程学报,2014,36(4):1008-1013.
[8]祝意青,徐云马,吕弋培,等.龙门山断裂带重力变化与汶川8.0关系研究[J].地球物理学报,2009,52(10):2538-2101.
[9]罗翔飞,秦建增,李真,等.华北中部地区重力场时空动态演化特征[J].地震工程学2015,37(3):687-692.
[10]罗翔飞,秦建增,方盛明,等.宜川一泰安剖面重力异常与构造意义[J].大地测量与地球动力学,2016,36(4):354-358.
[11]宁夏回族自治区地质矿产局,宁夏回族自治区区域[M].北京:地质志地质出版社,1990:1.
[12]刘绍府,刘冬至,李辉,等.高精度重力测量平差及其软件[J].地震,1991,(4):57-66.
[13]孙少安,项爱民.区域重力场相对基准的建立[J].地壳形变与地震,1999,19(1):78-81.