中国西部及邻区活动地块边界带现代构造应力场
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摘要
利用哈佛全球矩心矩张量解数据和许忠淮认为1920—1999年可靠的中国大陆震源机制解数据,反演了中国西部及邻区活动地块边界带上现代构造应力场.通过对FMSI反演程序多次的输入和检验,得到了边界带上的应力场.边界带上最大主压应力σ1轴绝大多数近水平.在90°E以西的中国西部大陆及邻区,σ1轴水平方向基本上为近SN向;在青藏高原的东北部,σ1轴水平方向基本上为近NE向;在青藏高原的东南部,σ1轴水平方向绕喜马拉雅构造东端顺时针方向旋转.最小主压应力σ3轴倾角呈两极分布,西域地块区内活动地块边界带和青藏地块区内东北缘部分段σ3轴倾角较陡,而青藏地块区内σ3轴倾角近水平,所以西域地块区和青藏地块区内东北部相对于其它大部分青藏地块区,有更多的逆冲地震.应力场在同一个边界带具有非均匀性.北天山带、南天山带、西秦岭—德令哈带、岷山—龙门山带和安宁河—小江带的非均匀性相对要小一些,西昆仑带、海原—祁连带、东昆仑带、玛尼—玉树带、澜沧江带和滇西西边界带的非均匀性相对要大,而喀喇昆仑—嘉黎带和喜马拉雅带的非均匀性最显著.由于震源机制解数据的限制,本文给出的是边界带上部分段的应力场.
Contemporary tectonic stress field on boundaries of active tectonic blocks in and around western China mainland is obtained from the data of Harvard CMT solution and reliable focal mechanism solutions from 1920to 1999selected by Xu Zhonghuai.We obtained the stress field by testing input and checking FMSI code ( Gephart ) many times.Most of the maximum principalstressσ 1 axes on active tectonic boundaries are horizontal.To the west of 90°E in and around western China mainland,the horizontalσ 1 axes are nearly in N--S direction.In the northeastern area of Qingzang plateau,the horizontalσ 1 axes are nearly NE--SW.In the southeastern area of Qingzang plateau,the horizontalσ 1 axes turn around clockwise around eastern end of Himalaya arc.The minimum principal stressσ 3 axes show two dominant dip angles.In Xiyu active tectonic block region and on some segments of the northeastern edge of Qingzang plateau,the σ 3 axes are steep,while in the Qingzang block region theσ3axes are horizontal. So there are more thrust earthquakes in the Xiyu block region and on some segments of the northeastern edge of Qingzang plateau than in the Qingzang plateau block region.The stress field on the same active tectonic boundary is heterogeneous.On north Tianshan belt,south Tianshan belt,west Qinling-Delingha belt,Minshan--Longmenshan belt and Anninghe--Xiaojiang belt,the heterogeneity is relatively weak.On west Kunlun belt,Haiyuan--Qilian belt,east Kunlun belt,Mani--Yushu belt,Lancangjiang belt and western belt of west Yunnan block,the heterogeneity is relatively strong.The heterogeneity on Kalakunlun--Jiali belt and Himalaya belt is more notable.Due to limited focal mechanism data,this paper only gave the stress field on some segments of the active tectonic block boundaries.
Contemporary tectonic stress field on boundaries of active tectonic blocks in and around western China mainland is obtained from the data of Harvard CMT solution and reliable focal mechanism solutions from 1920to 1999selected by Xu Zhonghuai.We obtained the stress field by testing input and checking FMSI code ( Gephart ) many times.Most of the maximum principalstressσ 1 axes on active tectonic boundaries are horizontal.To the west of 90°E in and around western China mainland,the horizontalσ 1 axes are nearly in N--S direction.In the northeastern area of Qingzang plateau,the horizontalσ 1 axes are nearly NE--SW.In the southeastern area of Qingzang plateau,the horizontalσ 1 axes turn around clockwise around eastern end of Himalaya arc.The minimum principal stressσ 3 axes show two dominant dip angles.In Xiyu active tectonic block region and on some segments of the northeastern edge of Qingzang plateau,the σ 3 axes are steep,while in the Qingzang block region theσ3axes are horizontal. So there are more thrust earthquakes in the Xiyu block region and on some segments of the northeastern edge of Qingzang plateau than in the Qingzang plateau block region.The stress field on the same active tectonic boundary is heterogeneous.On north Tianshan belt,south Tianshan belt,west Qinling-Delingha belt,Minshan--Longmenshan belt and Anninghe--Xiaojiang belt,the heterogeneity is relatively weak.On west Kunlun belt,Haiyuan--Qilian belt,east Kunlun belt,Mani--Yushu belt,Lancangjiang belt and western belt of west Yunnan block,the heterogeneity is relatively strong.The heterogeneity on Kalakunlun--Jiali belt and Himalaya belt is more notable.Due to limited focal mechanism data,this paper only gave the stress field on some segments of the active tectonic block boundaries.
引文
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谢富仁,崔效锋,赵建涛,陈群策,李宏.2004.中国大陆及邻区现代构造应力场分区[J].地球物理学报,47(4):654--662.
许忠淮,阎明,赵仲和.1983.由多个小震推断的华北地区构造应力场的方向[J].地震学报,5(3):268--279.
许忠淮,戈澍谟.1984.用滑动方向拟合法反演富蕴地震断裂带应力场[J].地震学报,8(5):395--404.
许忠淮,汪素云,黄雨蕊,高阿甲,金小锋,常向东.1987.由多个小震推断的青甘和川滇地区地壳应力场的方向特征[J].地球物理学报,30(5):476--486.
许忠淮,汪素云,黄雨蕊,高阿甲.1989.由大量地震资料推断我国大陆构造应力场[J].地球物理学报,35(5):560--572
许忠淮.2001.东亚地区现今构造应力图的编制[J].地震学报,23(5):492--501.
薛宏远,鄢家全.1984.鄂尔多斯地块周围的现代地壳应力场[J].地球物理学报,27(2):144--152.
张国民,张培震.2000.“大陆强震机理与预测”中期学术进展[J].中国基础科学,(10):4--10.
张国民,马宏生,王辉,王新岭.2005.中国大陆活动地块边界带与强震活动[J].地球物理学报,48(3):138--146.
张培震,邓起东,张国民,马瑾,甘卫军,闵伟,毛凤英,王琪.2003.中国大陆的强震活动与活动地块[J].中国科学:D辑,33(增刊):12--20.
Gephart J W.1990.FMSI:A fortran program for inverting fault/slickenside and earthquake focal mechanism data toobtain the original stress tensor[J].Comput Geosci,16(7):953--989.
Gephart J W,Forsyth D W.1984.An improved method for determining the regional stress tensor using focal mechanismdata:Application to the San Fernando earthquake sequence[J].J Geophys Res,89(B11):9305--9320.
Wan Y G.2010.Contemporary tectonic stress field in China[J].Earthq Sci,23(4):377--386.
Zoback M L.1992.First-and second-order patterns of stress in the lithosphere:The world stress map project[J].J Geophys Res,97(B8):11703--11728.
杜兴信,邵辉成.1999.由震源机制解反演中国大陆现代构造应力场[J].地震学报,21(4):354--360.
李钦祖,王泽皋,贾云年,靳雅敏.1973.由单台小地震资料所得两个区域的应力场[J].地球物理学报,16(1):49--61.
李延兴,杨国华,李智,郭良迁,黄珹,朱文耀,符养,王琪,江在森,王敏.2003.中国大陆活动地块的运动与应变状态[J].中国科学:D辑,33(增刊):65--81.
马宏生,张国民,刘杰,李丽,陈化然.2006.中国大陆活动地块边界带强震活动特征的研究[J].地震地质,28(1):48--60.
康英,杨选,陈杏,陈贵美,郑斯华.2008.广东及邻区的应力场反演[J].地震学报,30(1):59--66.
汪素云,许忠淮.1985.中国东部大陆的地震构造应力场[J].7(1):17--22.
谢富仁,刘光勋.1989.阿尔金断裂带中段区域新构造应力场分析[J].中国地震,5(3):26--36.
谢富仁,祝景忠,粱海庆,刘光勋.1993.中国西南地区现代构造应力场基本特征[J].地震学报,15(4):407--417.
谢富仁,陈群策,崔效锋,李宏,杨树新,陈连旺.2003.中国大陆地壳应力环境研究[M].北京:地质出版社:3--12.
谢富仁,崔效锋,赵建涛,陈群策,李宏.2004.中国大陆及邻区现代构造应力场分区[J].地球物理学报,47(4):654--662.
许忠淮,阎明,赵仲和.1983.由多个小震推断的华北地区构造应力场的方向[J].地震学报,5(3):268--279.
许忠淮,戈澍谟.1984.用滑动方向拟合法反演富蕴地震断裂带应力场[J].地震学报,8(5):395--404.
许忠淮,汪素云,黄雨蕊,高阿甲,金小锋,常向东.1987.由多个小震推断的青甘和川滇地区地壳应力场的方向特征[J].地球物理学报,30(5):476--486.
许忠淮,汪素云,黄雨蕊,高阿甲.1989.由大量地震资料推断我国大陆构造应力场[J].地球物理学报,35(5):560--572
许忠淮.2001.东亚地区现今构造应力图的编制[J].地震学报,23(5):492--501.
薛宏远,鄢家全.1984.鄂尔多斯地块周围的现代地壳应力场[J].地球物理学报,27(2):144--152.
张国民,张培震.2000.“大陆强震机理与预测”中期学术进展[J].中国基础科学,(10):4--10.
张国民,马宏生,王辉,王新岭.2005.中国大陆活动地块边界带与强震活动[J].地球物理学报,48(3):138--146.
张培震,邓起东,张国民,马瑾,甘卫军,闵伟,毛凤英,王琪.2003.中国大陆的强震活动与活动地块[J].中国科学:D辑,33(增刊):12--20.
Gephart J W.1990.FMSI:A fortran program for inverting fault/slickenside and earthquake focal mechanism data toobtain the original stress tensor[J].Comput Geosci,16(7):953--989.
Gephart J W,Forsyth D W.1984.An improved method for determining the regional stress tensor using focal mechanismdata:Application to the San Fernando earthquake sequence[J].J Geophys Res,89(B11):9305--9320.
Wan Y G.2010.Contemporary tectonic stress field in China[J].Earthq Sci,23(4):377--386.
Zoback M L.1992.First-and second-order patterns of stress in the lithosphere:The world stress map project[J].J Geophys Res,97(B8):11703--11728.
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