滇缅弧—达曼强震活动带地震应力图像研究
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摘要
为对云南强震活动趋势分析提供科学依据,基于Haskell二维地震位错模型,建立了用地震矩M0和体波震级mb估算地震震源构造剪应力强度τ0值的关系,并利用此关系,根据美国地质调查局提供的1977~2005年间东亚滇缅弧—安达曼地震活动带上强震活动的震源机制解、地震矩M0和体波震级mb,对该区的地震应力图像和板缘动力学机制特征进行了深入分析。结果表明:缅甸弧—安达曼板缘地震带的强震活动主要反映了板缘地震活动的特点,其平均剪应力τ0值为8.8 MPa;云南及喜马拉雅山地区的少量强震活动主要反映了板内地震活动的特征,其平均剪应力τ0值为13.5 MPa,板内地震统计得出的平均剪应力值是板缘地震的1.5倍。喜马拉雅山弧形区域主压应力方向(P轴)优势方向为NE向,但青藏高原东南的云南地区则表现出向ES方向的强烈偏转,这可能是由于印度板块与欧亚板块的强烈碰撞挤压以及缅甸弧的弧后扩张相互作用引起的。
In order to provide scientific basis for the seismicity tendency analysis of the Yunnan region,we build the relation to estimate shear stress value τ0 with seismic moment M0 and body wave magnitude mb based on the Haskell two-dimensional seismic dislocations model.We use the relation to estimate the τ0 value in the Yunnan-Burma arc and Andaman seismic zone according to the 1977-2005 data from USGS in the area,and analyze the image of stress and the characteristics of intraplate dynamic mechanism in the area.The analytical results indicate that the earthquakes in Burma arc and Andaman seismic zone mainly characterize interplate seismicity,and the average τ0 value is 8.8 Mpa;the earthquakes in the other areas mainly characterize intraplate seismicity,and the average τ0 value is 13.5 Mpa,about 1.5 times as much as that of interplate earthquakes.In the Himalaya mountains arc area,the compressive stress is in NE direction,while in the Yunnan region southeast of Qinghai-Tibet Plateau,the compressive stress shows a remarkable rotation toward SE direction,which may be caused by the joint effect of the continental collision and extrusion between the India and Eurasia plates and the back-arc extension in the Burma arc region.
In order to provide scientific basis for the seismicity tendency analysis of the Yunnan region,we build the relation to estimate shear stress value τ0 with seismic moment M0 and body wave magnitude mb based on the Haskell two-dimensional seismic dislocations model.We use the relation to estimate the τ0 value in the Yunnan-Burma arc and Andaman seismic zone according to the 1977-2005 data from USGS in the area,and analyze the image of stress and the characteristics of intraplate dynamic mechanism in the area.The analytical results indicate that the earthquakes in Burma arc and Andaman seismic zone mainly characterize interplate seismicity,and the average τ0 value is 8.8 Mpa;the earthquakes in the other areas mainly characterize intraplate seismicity,and the average τ0 value is 13.5 Mpa,about 1.5 times as much as that of interplate earthquakes.In the Himalaya mountains arc area,the compressive stress is in NE direction,while in the Yunnan region southeast of Qinghai-Tibet Plateau,the compressive stress shows a remarkable rotation toward SE direction,which may be caused by the joint effect of the continental collision and extrusion between the India and Eurasia plates and the back-arc extension in the Burma arc region.
引文
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Zoback M L·1992·First-and second-order pattern of stress in the litho-sphere:the world stress project[J].JGR,97(B8):11703-11728
钱晓东,邬成栋,秦嘉政·2004·用环境应力参数对云南地区进行地震短临跟综监视[J].地震研究,27(1):1-7·
钱晓东,秦嘉政,叶建庆·2006·云南地区的环境应力参数及其在地震短临预报中的应用[J].地震研究,29(1):7-12·
秦嘉政,皇甫岗,钱晓东·2005·云南强震活动与中短期预测技术研究[M].昆明:云南科技出版社·
肖磊,陈培善·1997·全球主要地震活动带上的应力分布图像[J].地震学报,19(2):129-138·
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·
臧绍先,吴忠良·1991·南海、中印半岛及其邻近地区的地震活动及应力状态[J].地震学报,13(2):129-138·
Kanamori H,Anderson D L·1975·Theoretical basis of some empiricalrelations in seismology[J].BSSA,65(4):1073-1095·
LagT,Kanamori H·2005·The great Sumatra-Andaman earthquake of26December2004[J].Science,308:1127-1133·
Lithgow-Bertelloni C,Guynn J H·2004·Origin of the lithospheric stressfield[J].JGR,109(B1):1-32·
Park J,Anderson D L·2005·Global seismographic network records thegreat Sumatra-Andaman earthquake[J].Eos Trans AGU,86(6):57-61·
Zoback M L·1992·First-and second-order pattern of stress in the litho-sphere:the world stress project[J].JGR,97(B8):11703-11728
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