张渤带陆地段现代构造应力场的非均匀特征
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摘要
依据活动构造展布及震中分布等情况,将张渤带(张家口-渤海断裂带)陆地段及邻近地区划分为6个应力区,利用格点尝试法计算了1967～2006年间这6个分区内的529个震源机制解。结果显示,6个分区的应力结构较为一致,均为走滑型应力结构;但在应力方向上有明显不同,其应力主轴方向有由西北端的NEE向至东南端的近EW向呈顺时针旋转的趋势。此外,以1976年唐山地震与1998年张北地震为时间界限,计算了张渤带陆地段3个构造交汇段(即张北-怀来段、南口-三河段、天津-塘沽段,简称西段、中段、东段)上的地震震源机制解及各构造段在不同时段的平均主应力轴分布,得到了应力场随时间的变化特征。其中,西段与中段的构造应力场变化复杂,其应力主轴方向在唐山地震后经调整已基本回复至唐山地震前的状态;而东段的平均应力主轴呈顺时针旋转,目前仍为近EW向。张渤带陆地段现代构造应力场的时空非均匀变化特征可能与周边块体的相互作用及两次中强地震(唐山地震与张北地震)有关。
According to the distribution of active tectonic and earthquake epicenters,the Zhangjiakou-Bohai Fault Zone and its adjacent areas are divided into six stress districts.We use the Grid Test Method to calculate more than 500 earthquake focal mechanism solutions of these 6 districts in the period of 1977～2006.The calculated result indicates that the stress regimes of these 6 stress districts are identical and they are all of strike slip.However,there are some changes in the orientations of tectonic stress fields.On the whole,the orientation of principal stress axes is in NEE-nearly EW direction from northwest to southeast;it shows a trend of clockwise rotation.In addition,taking the Tangshan earthquake and the Zhangbei earthquake as time bound,we calculate the focal mechanism solutions of 3 tectonic merging parts(they are west part,middle part and east part respectively) in the Zhangjiakou-Bohai Fault Zone in 3 different time-intervals,and we get the time-varying characteristics of the orientation of the present tectonic stress field.The state of tectonic stress field is complex in west and middle part,the orientation of principal stress axes in both parts seems to return to the state before the Tangshan earthquake by adjusting for several years;but the orientation of principal stress axis in the east part is still in nearly EW direction at present;it does not return to the state before the Tangshan earthquake and it shows a clockwise rotation.The temporal and spatial heterogeneity of the present tectonic stress field at the overland part of the Zhangjiakou-Bohai Fault Zone may have a relation to the interaction of peripheral blocks and two moderately strong earthquakes.
According to the distribution of active tectonic and earthquake epicenters,the Zhangjiakou-Bohai Fault Zone and its adjacent areas are divided into six stress districts.We use the Grid Test Method to calculate more than 500 earthquake focal mechanism solutions of these 6 districts in the period of 1977～2006.The calculated result indicates that the stress regimes of these 6 stress districts are identical and they are all of strike slip.However,there are some changes in the orientations of tectonic stress fields.On the whole,the orientation of principal stress axes is in NEE-nearly EW direction from northwest to southeast;it shows a trend of clockwise rotation.In addition,taking the Tangshan earthquake and the Zhangbei earthquake as time bound,we calculate the focal mechanism solutions of 3 tectonic merging parts(they are west part,middle part and east part respectively) in the Zhangjiakou-Bohai Fault Zone in 3 different time-intervals,and we get the time-varying characteristics of the orientation of the present tectonic stress field.The state of tectonic stress field is complex in west and middle part,the orientation of principal stress axes in both parts seems to return to the state before the Tangshan earthquake by adjusting for several years;but the orientation of principal stress axis in the east part is still in nearly EW direction at present;it does not return to the state before the Tangshan earthquake and it shows a clockwise rotation.The temporal and spatial heterogeneity of the present tectonic stress field at the overland part of the Zhangjiakou-Bohai Fault Zone may have a relation to the interaction of peripheral blocks and two moderately strong earthquakes.
引文
崔效锋、谢富仁,2001,1976年唐山地震前后华北地区现代构造应力场的时空变化特征,中国地震,17(3),280～288。
刁桂苓、王海涛、高国英等,2005,伽师强震系列应力场的转向过程,地球物理学报,48(5),1062～1068。
刁桂苓、高国英、聂小红等,2007,伽师序列中小地震震源机制分析,国际地震动态,(12),1～9。
范俊喜、马瑾、刁桂苓,2003,由小震震源机制解得到的鄂尔多斯周边构造应力场,地震地质,25(1),88～99。
何建坤、刘福田、刘建华等,1998,华北东部中新生代盆地构造特征与大陆动力学过程,陈等主编,寸丹集——庆贺刘光鼎院士工作50周年学术论文集,618～632,北京:科学出版社。
胡新亮、刁桂苓、马瑾等,2004,利用数字地震记录的P-,-S振幅比资料测定小震震源机制解的可靠性分析,地震地质,26(2),347～354。
李钦祖、王泽皋、贾云年等,1973,由单台小地震资料所得两个区域的应力场,地球物理学报,16(1),49～61。
李延兴、张静华、郭良迁等,2005,鄂尔多斯的逆时针旋转与动力学,大地测量与地球动力学,25(3),50～56。
梁尚鸿、李幼铭、束沛溢等,1984,利用区域地震台网P、S振幅比资料测定小震震源参数,地球物理学报,27(3),247～257。
刘和甫,2001,盆地-山岭耦合体系与地球动力学机制,地球科学,26(6),581～596。
孙武城、祝治平、张利等,1988,对华北地壳上地幔的探测与研究,见:国家地震局科技监测司编,中国大陆深部构造的研究与进展,19～37,北京:地质出版社。
王夫运、张先康、陈湧等,2004,张渤构造带中东段二维P波速度结构-安新-香河-宽城剖面,地震学报,26(Supp.),31～41。
徐杰、牛娈芳、王春华等,1996,唐山-河间-磁县新生地震构造带,地震地质,19(3),193～198。
徐杰、宋长青、楚全芝,1998,张家口-蓬莱断裂带地震构造特征的初步探讨,地震地质,20(2),146～154。
谢富仁、崔效锋、赵建涛等,2004,中国大陆及邻区现代构造应力场分区,地球物理学报,47(4),654～662。
许向彤、许忠淮、张东宁,1995,求震源机制P波初动解的格点尝试概率法,地震地磁观测与研究,16(4),34～42。
许忠淮、阎明、赵仲和,1983,由多个小地震推断的华北地区构造应力场的方向,地震学报,5(3),268～279。
许忠淮,1985,用滑动方向拟合法反演唐山余震区的平均应力场,地震学报,7(4),349～361。
张成科、张先康、赵金仁等,2002,渤海湾及其邻区壳幔速度结构研究与综述,地震学报,24(4),428～435。
张先康、王椿镛、刘国栋等,1996,延庆-怀来地区地壳细节构——利用深地震反射剖面,地球物理学报,39(3),356～364。
张先康、祝治平、张成科等,1998,张家口-渤海地震带及其两侧地壳上地幔构造与速度结构研究,见:活动断裂研究编委会和中国地震局科技发展司编,活动断裂研究(6),北京:地震出版社,1～16。
郑炳华、虢顺民、徐杰等,1980,燕山地区大地构造基本轮廓,中国科学院地质研究所,国家地震局地质研究编,华北断块区的形成与发展,北京:科学出版社,170～178。
赵金仁、张先康、张成科等,1999,香河-北京-涿鹿及其相邻地区壳幔构造与速度结构特征,地震地质,21(1),29～36。
Aki K,1966,Earthquake generating stress in Japanfor the years1961to1963obtained by smoothingthe first motion radiation patterns.Bull Earthq Res Inst,44(2),447～471.
Ellsworth WL,Xu Zhonghuai,1980,Determination of the stresstensor fromfocal mechanismdata.EOS Trans Amer Geophys Union,61,1117.
Michael AJ,1987,Use of focal mechanismto determine stress,Acontrol study.J.Geophys.Res,92,357～368.
刁桂苓、王海涛、高国英等,2005,伽师强震系列应力场的转向过程,地球物理学报,48(5),1062～1068。
刁桂苓、高国英、聂小红等,2007,伽师序列中小地震震源机制分析,国际地震动态,(12),1～9。
范俊喜、马瑾、刁桂苓,2003,由小震震源机制解得到的鄂尔多斯周边构造应力场,地震地质,25(1),88～99。
何建坤、刘福田、刘建华等,1998,华北东部中新生代盆地构造特征与大陆动力学过程,陈等主编,寸丹集——庆贺刘光鼎院士工作50周年学术论文集,618～632,北京:科学出版社。
胡新亮、刁桂苓、马瑾等,2004,利用数字地震记录的P-,-S振幅比资料测定小震震源机制解的可靠性分析,地震地质,26(2),347～354。
李钦祖、王泽皋、贾云年等,1973,由单台小地震资料所得两个区域的应力场,地球物理学报,16(1),49～61。
李延兴、张静华、郭良迁等,2005,鄂尔多斯的逆时针旋转与动力学,大地测量与地球动力学,25(3),50～56。
梁尚鸿、李幼铭、束沛溢等,1984,利用区域地震台网P、S振幅比资料测定小震震源参数,地球物理学报,27(3),247～257。
刘和甫,2001,盆地-山岭耦合体系与地球动力学机制,地球科学,26(6),581～596。
孙武城、祝治平、张利等,1988,对华北地壳上地幔的探测与研究,见:国家地震局科技监测司编,中国大陆深部构造的研究与进展,19～37,北京:地质出版社。
王夫运、张先康、陈湧等,2004,张渤构造带中东段二维P波速度结构-安新-香河-宽城剖面,地震学报,26(Supp.),31～41。
徐杰、牛娈芳、王春华等,1996,唐山-河间-磁县新生地震构造带,地震地质,19(3),193～198。
徐杰、宋长青、楚全芝,1998,张家口-蓬莱断裂带地震构造特征的初步探讨,地震地质,20(2),146～154。
谢富仁、崔效锋、赵建涛等,2004,中国大陆及邻区现代构造应力场分区,地球物理学报,47(4),654～662。
许向彤、许忠淮、张东宁,1995,求震源机制P波初动解的格点尝试概率法,地震地磁观测与研究,16(4),34～42。
许忠淮、阎明、赵仲和,1983,由多个小地震推断的华北地区构造应力场的方向,地震学报,5(3),268～279。
许忠淮,1985,用滑动方向拟合法反演唐山余震区的平均应力场,地震学报,7(4),349～361。
张成科、张先康、赵金仁等,2002,渤海湾及其邻区壳幔速度结构研究与综述,地震学报,24(4),428～435。
张先康、王椿镛、刘国栋等,1996,延庆-怀来地区地壳细节构——利用深地震反射剖面,地球物理学报,39(3),356～364。
张先康、祝治平、张成科等,1998,张家口-渤海地震带及其两侧地壳上地幔构造与速度结构研究,见:活动断裂研究编委会和中国地震局科技发展司编,活动断裂研究(6),北京:地震出版社,1～16。
郑炳华、虢顺民、徐杰等,1980,燕山地区大地构造基本轮廓,中国科学院地质研究所,国家地震局地质研究编,华北断块区的形成与发展,北京:科学出版社,170～178。
赵金仁、张先康、张成科等,1999,香河-北京-涿鹿及其相邻地区壳幔构造与速度结构特征,地震地质,21(1),29～36。
Aki K,1966,Earthquake generating stress in Japanfor the years1961to1963obtained by smoothingthe first motion radiation patterns.Bull Earthq Res Inst,44(2),447～471.
Ellsworth WL,Xu Zhonghuai,1980,Determination of the stresstensor fromfocal mechanismdata.EOS Trans Amer Geophys Union,61,1117.
Michael AJ,1987,Use of focal mechanismto determine stress,Acontrol study.J.Geophys.Res,92,357～368.
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