河北文安5.1级地震前后重力场动态变化
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摘要
分析了2006年7月4日文安5.1级地震前后文霸流动重力测网的观测结果,讨论了垂直形变和浅层地下水位变化引起的重力改变,并对重力资料进行了高程改正。研究结果认为,文安地震前后,测网出现了明显的异常变化,测区的重力异常以重力上升为主,且上升幅度大的区域主要在测网南部;地震震中在震前形成重力高梯度带,2005年10月至2006年4月短期内的重力变化表现最为明显;测区内的正负重力变化的分界线,地震前后出现逐渐偏转的特点,且在2007年10月逐渐恢复。
In order to explore the abnormal gravity variations before and after the Wen′an M5.1 earthquake occurred on July 4 2006,the data observed by Wenba gravity observation network before and after the earthquake are analyzed.The relations between gravity change with vertical displacement and shallow groundwater level were discussed,and elevation effects are corrected.The results show that there were abnormal gravity changes before the M5.1 earthquake,which appeared as gravity rising in the whole observation network especially in the south part of it.High gradient of gravity variation appeared around the epicenter before the M5.1 earthquake,especially during the short period from October 2005 to April 2006.The boundary between the positive and negative gravity variations was gradually deflected and began recovering from October 2007.
In order to explore the abnormal gravity variations before and after the Wen′an M5.1 earthquake occurred on July 4 2006,the data observed by Wenba gravity observation network before and after the earthquake are analyzed.The relations between gravity change with vertical displacement and shallow groundwater level were discussed,and elevation effects are corrected.The results show that there were abnormal gravity changes before the M5.1 earthquake,which appeared as gravity rising in the whole observation network especially in the south part of it.High gradient of gravity variation appeared around the epicenter before the M5.1 earthquake,especially during the short period from October 2005 to April 2006.The boundary between the positive and negative gravity variations was gradually deflected and began recovering from October 2007.
引文
[1]孙和平.重力场的时间变化与地球动力学[J].中国科学院院刊,2004,19(3):189-193.
[2]刁桂苓,张四昌,孙佩卿,等.2006年7月4日文安5.1级地震[J].地震地质,2006,28(3):497-502.
[3]张晶,江在森,方颖,等.文安地震与首都圈地区数字化应变资料分析[J].地震,2007,27(1):39-46.
[4]张晶,陈荣华,王武星.文安地震与区域应变场变化综合研究[J].大地测量与地球动力学,2008,28(1):28-31.
[5]杨国华,韩月萍,谢觉民,等.首都圈地壳垂直形变与未来强震活动[J].地震,2002,22(3):27-32.
[6]韩月萍,杨国华,塔拉,等.首都圈及晋冀蒙交界地区地壳垂直形变及地震危险性分析[J].山西地震,2007,3:7-10.
[7]许月卿,蔡运龙.基于GIS的河北平原地下水位时空变化动态分析[J].北京大学学报(自然科学版),2005,41(2):265-272.
[2]刁桂苓,张四昌,孙佩卿,等.2006年7月4日文安5.1级地震[J].地震地质,2006,28(3):497-502.
[3]张晶,江在森,方颖,等.文安地震与首都圈地区数字化应变资料分析[J].地震,2007,27(1):39-46.
[4]张晶,陈荣华,王武星.文安地震与区域应变场变化综合研究[J].大地测量与地球动力学,2008,28(1):28-31.
[5]杨国华,韩月萍,谢觉民,等.首都圈地壳垂直形变与未来强震活动[J].地震,2002,22(3):27-32.
[6]韩月萍,杨国华,塔拉,等.首都圈及晋冀蒙交界地区地壳垂直形变及地震危险性分析[J].山西地震,2007,3:7-10.
[7]许月卿,蔡运龙.基于GIS的河北平原地下水位时空变化动态分析[J].北京大学学报(自然科学版),2005,41(2):265-272.
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