利用多个震源机制解求东大别地区平均应力场
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摘要
利用地震的震源机制解资料,得到应力张量在地理坐标系下的表达式,进而可计算平均应力张量.通过求平均应力张量的本征向量,即可得到其主轴方向,并由此推断区域应力场方向.利用东大别地区219次地震的震源机制解资料,比较了不同相似程度和不同起算震级资料得到的主轴方向,认为该方法计算结果非常稳定,主轴方位角的误差小于5°,倾角的误差小于10°.计算结果表明,东大别地区最大主压应力轴σ1的方位角为267°,倾角为5°;最小主压应力轴σ3的方位角为358°,倾角为4°.表明该地区受东西向的水平挤压和南北向的水平拉张作用.
By stacking focal mechanism parameters of a group of earthquakes we present an expression of mean stress tensor for a region in geographic coordinates. We calculated average stress tensor and its eigenvectors to get the directions of principal axes, which may represent the directions of regional principal stress axes. By analyzing focal mechanism parameters of 219 moderate and small earthquakes we have inferred mean principal stress directions for this region. Results of testing this method by sampling different data sets indicate that this method is simple in use and the results are stable. The error of azimuth of principal axes is estimated to be less than 5 °, and that of plunge is less than 10°. The mean regional stress parameters we obtained are as follows:The azimuth of maximum principal (compressive) stress axis (compression axis), σ1, is 267°and its plunge is 5°;azimuth of minimum principal (compressive) stress axis (tension axis), σ3, is 358°and its plunge is 4°. This indicates that the eastern Dabie region is horizontally compressed nearly in E-W direction, and its relative horizontal extension is nearly in N-S.
By stacking focal mechanism parameters of a group of earthquakes we present an expression of mean stress tensor for a region in geographic coordinates. We calculated average stress tensor and its eigenvectors to get the directions of principal axes, which may represent the directions of regional principal stress axes. By analyzing focal mechanism parameters of 219 moderate and small earthquakes we have inferred mean principal stress directions for this region. Results of testing this method by sampling different data sets indicate that this method is simple in use and the results are stable. The error of azimuth of principal axes is estimated to be less than 5 °, and that of plunge is less than 10°. The mean regional stress parameters we obtained are as follows:The azimuth of maximum principal (compressive) stress axis (compression axis), σ1, is 267°and its plunge is 5°;azimuth of minimum principal (compressive) stress axis (tension axis), σ3, is 358°and its plunge is 4°. This indicates that the eastern Dabie region is horizontally compressed nearly in E-W direction, and its relative horizontal extension is nearly in N-S.
引文
刁桂苓,于利民,李钦祖.1992.震源机制解的系统聚类分析:以海城地震序列为例[J].中国地震,8(3):86-92.
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,5(3):268-279.
梁尚鸿,李幼铭,束沛镒,朱碚定.1984.利用区域地震台网Pg,Sg波振幅比资料测定小震震源参数[J].地球物理学报,27(3):249-257.
刘东旺,刘泽民,沈小七,夏瑞良,李敏莉,闫素萍,凌学书.2004.安徽淮河构造变形带及邻近块体现代构造应力场特征[J].中国地震,20(4):364-371.
刘启元,Rainer Kind,陈九辉,Yuan Xiaohui,李顺成,郭飚,Kurt Wylegalla,赖院根.2005.大别造山带壳幔界面的断错结构和壳内低速体[J].中国科学:D辑,35(4):304-313.
吕坚,郑勇,倪四道,高建华.2008.2005年11月26日九江—瑞昌MS5.7、MS4.8地震的震源机制解与发震构造研究[J].地球物理学报,51(1):158-164.
潘国强,赵连泽,夏木林.1997.大别山碰撞造山带的构造模型及其地质演化[J].中国区域地质,16(1):43-50.
王椿镛,张先康,陈步云.1997.大别造山带的地壳结构研究[J].中国科学:D辑,27(3):221-226.
王椿镛,楼海,王飞.1999.大别山超高压变质带地壳结构及其构造意义[J].地震学报,21(5):533-544.
夏瑞良.1985.安徽区域地震应力场的分布特征[J].地震地质,7(3):13-21.
许忠淮,阎明,赵忠和.1983.由多个小地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.1985.用滑动方向拟合法反演唐山余震区的平均应力场[J].地震学报,7(4):349-361.
许忠淮.2001.东亚地区现今构造应力场的编制[J].地震学报,23(5):492-501.
钟继茂,程万正.2006.由多个地震震源机制解求川滇地区平均应力场方向[J].地震学报,28(4):337-346.
周翠英,华爱军,王梅,张来荣,马玉香.1997.1995年苍山5.2级地震前应力场的动态变化[J].地震地质,19(2):135-140.
周翠英,王铮铮,蒋海昆,李永红,吴延河.2005.华东地区现代地壳应力场及地震断层错动性质[J].地震地质,27(2):273-288.
Aki K,Richards P G.1980.Quantitative Seismology:Theory and Methods Vol.1[M].San Francisco:Freeman and Company:114.
Angelier J.1979.Determination of the mean principal direction of stresses for given fault population[J].Tectonophysisc,56(3-4):17-26.
Angelier J,Tarantola A,Valette B,Manoussis S.1982.Inversion of field data in fault tectonics to obtain the regional stress-1.Single phase fault populations:A new method of computing the stress tensor[J].J Geophys Res,69(3):607-621.
Boot M H P.1959.The mechanics of oblique slip faulting[J].Geol Mag,96(2):109-117.
Ellsworth W L,Xu Z H.1980.Determination of the stress tensor from focal mechanism data[J].Eos Trans AGU,61:1117.
McKenzie D P.1969.The relation between fault plane solution for earthquakes and the directions of the principal stress[J].Computer &Geosciences,16(7):953-989.
Raleigh C B,Healy J H,Bredehoeft J D.1972.Faulting and crustal stress at Rangely,Colorado[G]∥Heard H C,Borg I Y,Carter N L,Raleigh C B eds.American Geophysical Union Geophysical Monograph Series,16:Flow and Fracture of Rocks.Washington D C:AGU:275-284.
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,5(3):268-279.
梁尚鸿,李幼铭,束沛镒,朱碚定.1984.利用区域地震台网Pg,Sg波振幅比资料测定小震震源参数[J].地球物理学报,27(3):249-257.
刘东旺,刘泽民,沈小七,夏瑞良,李敏莉,闫素萍,凌学书.2004.安徽淮河构造变形带及邻近块体现代构造应力场特征[J].中国地震,20(4):364-371.
刘启元,Rainer Kind,陈九辉,Yuan Xiaohui,李顺成,郭飚,Kurt Wylegalla,赖院根.2005.大别造山带壳幔界面的断错结构和壳内低速体[J].中国科学:D辑,35(4):304-313.
吕坚,郑勇,倪四道,高建华.2008.2005年11月26日九江—瑞昌MS5.7、MS4.8地震的震源机制解与发震构造研究[J].地球物理学报,51(1):158-164.
潘国强,赵连泽,夏木林.1997.大别山碰撞造山带的构造模型及其地质演化[J].中国区域地质,16(1):43-50.
王椿镛,张先康,陈步云.1997.大别造山带的地壳结构研究[J].中国科学:D辑,27(3):221-226.
王椿镛,楼海,王飞.1999.大别山超高压变质带地壳结构及其构造意义[J].地震学报,21(5):533-544.
夏瑞良.1985.安徽区域地震应力场的分布特征[J].地震地质,7(3):13-21.
许忠淮,阎明,赵忠和.1983.由多个小地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.1985.用滑动方向拟合法反演唐山余震区的平均应力场[J].地震学报,7(4):349-361.
许忠淮.2001.东亚地区现今构造应力场的编制[J].地震学报,23(5):492-501.
钟继茂,程万正.2006.由多个地震震源机制解求川滇地区平均应力场方向[J].地震学报,28(4):337-346.
周翠英,华爱军,王梅,张来荣,马玉香.1997.1995年苍山5.2级地震前应力场的动态变化[J].地震地质,19(2):135-140.
周翠英,王铮铮,蒋海昆,李永红,吴延河.2005.华东地区现代地壳应力场及地震断层错动性质[J].地震地质,27(2):273-288.
Aki K,Richards P G.1980.Quantitative Seismology:Theory and Methods Vol.1[M].San Francisco:Freeman and Company:114.
Angelier J.1979.Determination of the mean principal direction of stresses for given fault population[J].Tectonophysisc,56(3-4):17-26.
Angelier J,Tarantola A,Valette B,Manoussis S.1982.Inversion of field data in fault tectonics to obtain the regional stress-1.Single phase fault populations:A new method of computing the stress tensor[J].J Geophys Res,69(3):607-621.
Boot M H P.1959.The mechanics of oblique slip faulting[J].Geol Mag,96(2):109-117.
Ellsworth W L,Xu Z H.1980.Determination of the stress tensor from focal mechanism data[J].Eos Trans AGU,61:1117.
McKenzie D P.1969.The relation between fault plane solution for earthquakes and the directions of the principal stress[J].Computer &Geosciences,16(7):953-989.
Raleigh C B,Healy J H,Bredehoeft J D.1972.Faulting and crustal stress at Rangely,Colorado[G]∥Heard H C,Borg I Y,Carter N L,Raleigh C B eds.American Geophysical Union Geophysical Monograph Series,16:Flow and Fracture of Rocks.Washington D C:AGU:275-284.
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