昆仑山口西8.1级地震震后中国西部地壳水平位移场的变化特征
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摘要
利用"中国地壳运动观测网络"基本站自1998年运行以来积累的观测资料,以2001年11月昆仑山口西8.1级地震前的所有资料计算的运动结果为基本参考,分别计算了2002年相对于2001年和以后几年相对于2002年的测站累计偏离位移变化结果,据此对昆仑山口西8.1级地震震时和震后中国西部水平运动场的变动进行了观察。结果表明:①以发震断裂为界,震时南侧的西藏地区发生了由北至东的偏离位移,数值超过10mm,北侧的新疆地区发生了NW向的偏离位移,最大值也超过了10mm;②震后(从2003年算起)左旋性质的偏离位移是断断续续的增加,截止到2005年,距震源最近的JB51(发震断裂南侧)和JB30(发震断裂北侧)站的地形变变化最大,相对达70mm;③震后发震断裂以南的西藏地区优势偏离位移向东,以北新疆地区的优势偏离位移向北北西,距震中越近偏离越大;④2006年,距震源最近的JB51和JB30站的偏离位移似乎有向反向移动的迹象,西藏地区基本上没有新的偏离,新疆地区的WNN向偏离位移似乎仍在进行。尽管地震发生距今已5年多了,但有关迹象表明,地壳水平形变场的有序调整可能尚未完全结束,也不排除震前西藏地区的运动由于孕震的缘故而略有所减慢的可能。
Since the basic stations of "China Crust Movement Measuring Network" run in 1998,the accumulated data are used,the calculating movement results by all data before 2001(before the Kunlun Mountain MS8.1 in November of 2001)are taken as the basic reference,we have respectively calculated the accumulated departure results of 2002 relative to 2001 and the succeeding several years relative to 2002.Based on this,the changes of the horizontal movement field in the west of China have been observed,while the Kunlun Mountain Ms8.1 earthquake occurred and after the earthquake.The results suggest:① Bounded by the seismic outbreak fault,in Tibet area of the south side,the departure displacement from north to east took place when the earthquake occurred,and the departure amount even exceeded 10mm,while in Xinjiang area of the north side,the departure displacement of the direction of NW took place,and the maximal amount also exceeded 10mm;② After the earthquake(from 2003),the laevogyrate departure displacement increased off and on,the variation of JB51(south side of the fault)and JB30(north side of the fault),which are the closest two stations to the epicenter,reached the largest up to 2005,and the relative amount was 70mm;③ After the earthquake,the preponderant departure displacement of Tibet area,which is to the south of the seismic outbreak fault,was eastward,while Xinjiang area,which is to the north of the seismic outbreak fault,was NNW,and the more close to the epicenter,the more large of the departure;④ The departure displacement of JB51 and JB30,which are the closest two stations to the epicenter,apparently had an evidence of reverse motion,and there wasn 't new departure in Tibet area basically,while in Xinjiang area,the departure displacement of the direction of WNN was apparently developing.Anyhow,though until now there has been more than 5 years since the earthquake occurred,the correlative evidence indicates that the ordinal adjustment of the crust horizontal deformation field probably doesn 't end completely,but we also don 't exclude the possibility that the movement in Tibet area slowed appreciably as a result of gestating seism before the earthquake.
Since the basic stations of "China Crust Movement Measuring Network" run in 1998,the accumulated data are used,the calculating movement results by all data before 2001(before the Kunlun Mountain MS8.1 in November of 2001)are taken as the basic reference,we have respectively calculated the accumulated departure results of 2002 relative to 2001 and the succeeding several years relative to 2002.Based on this,the changes of the horizontal movement field in the west of China have been observed,while the Kunlun Mountain Ms8.1 earthquake occurred and after the earthquake.The results suggest:① Bounded by the seismic outbreak fault,in Tibet area of the south side,the departure displacement from north to east took place when the earthquake occurred,and the departure amount even exceeded 10mm,while in Xinjiang area of the north side,the departure displacement of the direction of NW took place,and the maximal amount also exceeded 10mm;② After the earthquake(from 2003),the laevogyrate departure displacement increased off and on,the variation of JB51(south side of the fault)and JB30(north side of the fault),which are the closest two stations to the epicenter,reached the largest up to 2005,and the relative amount was 70mm;③ After the earthquake,the preponderant departure displacement of Tibet area,which is to the south of the seismic outbreak fault,was eastward,while Xinjiang area,which is to the north of the seismic outbreak fault,was NNW,and the more close to the epicenter,the more large of the departure;④ The departure displacement of JB51 and JB30,which are the closest two stations to the epicenter,apparently had an evidence of reverse motion,and there wasn 't new departure in Tibet area basically,while in Xinjiang area,the departure displacement of the direction of WNN was apparently developing.Anyhow,though until now there has been more than 5 years since the earthquake occurred,the correlative evidence indicates that the ordinal adjustment of the crust horizontal deformation field probably doesn 't end completely,but we also don 't exclude the possibility that the movement in Tibet area slowed appreciably as a result of gestating seism before the earthquake.
引文
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杨国华,江在森,刘广余,等.2007.华北地区水平运动场于昆仑山8.1级地震的可能关系[J].大地测量与地球动力学,27(2):10-5.
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中国地震局监测预报司.2002.2001年昆仑山口西8.1级大地震[M].北京:地震出版社,24-34.
顾国华,张晶,王武星.2003.关于2001年昆仑山8.1级大地震前后中国大陆水平运动的讨论[J].地震学报,25(6):653-660.
胡新康,王倩,马青,等.2007.区域无整体旋转基准的研究与应用[J].大地测量与地球动力学,27(2):52-60.
江在森,张希,祝意清,等.2003.昆仑山口西MS8.1地震前区域构造形变背景[J].中国科学(D辑),33(增刊):163-172.
李延兴,李智,张静华,等.2004.中国大陆及周边地区的水平应变场[J].地球物理学报,47(2):222-231.
乔学军,王琪,杜瑞林,等.2002.昆仑山口西MS8.1级地震的地壳形变特征[J].大地测量与地球动力学,22(4):6-11.
任金卫,王敏.2005.GPS观测的2001年昆仑山口西MS8.1级地震地壳形变[J].第四纪研究,25(1):34-44.
杨国华,江在森,武艳强,等.2005.中国大陆整体无净旋转基准及其应用[J].大地测量与地球动力学,25(4):6-10.
杨国华,江在森,王敏,等.2006.印尼地震对我国青藏高原东北缘地区地壳水平活动的影响[J].大地测量与地球动力学,26(1):9-14.
杨国华,江在森,刘广余,等.2007.华北地区水平运动场于昆仑山8.1级地震的可能关系[J].大地测量与地球动力学,27(2):10-5.
杨国华,李延兴,韩月萍,等.2002.中国西部地壳现今变形特征及其机制[J].测绘学报,31(4):292-299.
中国地震局监测预报司.2002.2001年昆仑山口西8.1级大地震[M].北京:地震出版社,24-34.
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