滇中地区震源机制一致性参数时空分布与强震活动
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摘要
利用云南数字地震台网记录到的地震直达波Pg、Sg振幅资料,采用层状介质中点源位错模型的广义透射系数的快速算法,计算理论地震图的Pg、Sg最大振幅比值,将其与观测值拟合,反演得到1999年至2009年11月14日滇中地区206个中小地震的震源机制解,计算震源机制解应力主轴与相应的区域构造应力场主轴之间的一致性参数,分析震源机制一致性参数时空分布与强震活动的关系。分析表明,强震发生前3年至数月,强震震源区附近出现多个震源释放应力场与区域应力场一致或接近的中小地震,强震就发生在中小震震源机制一致性参数低值分布区内或其边缘附近。
Adopting the amplitude data of the direct Pg and Sg wave recorded by the Yunnan Digital Seismic Network,using the fast algorithm of the generalized transmission coefficient for the Point Source Dislocation Model for the layered media,we calculate the maximum-amplitude ratios of P and S wave of theoretical seismograms,fit the observed values and get the focal mechanism solution of 206 moderate- and small- earthquakes from Jan.1,1999 to the November 14,2009 in central Yunnan through inversion.We calculate the consistency of focal mechanism parameters of the principal stress axis and the regional tectonic stress field,and analyze the relationship between the spatial and temporal distribution of the consistency of focal mechanism parameters and strong seismicity.The analysis showes that several moderate- and small- earthquakes whose stress-release fields are consistent or approximately consistent with the regional stress field occur near the source region of the strong earthquakes,and strong earthquakes will occur in the low-value area and its fringe of the consistent parameters of the moderate- and small- earthquaqkes.
Adopting the amplitude data of the direct Pg and Sg wave recorded by the Yunnan Digital Seismic Network,using the fast algorithm of the generalized transmission coefficient for the Point Source Dislocation Model for the layered media,we calculate the maximum-amplitude ratios of P and S wave of theoretical seismograms,fit the observed values and get the focal mechanism solution of 206 moderate- and small- earthquakes from Jan.1,1999 to the November 14,2009 in central Yunnan through inversion.We calculate the consistency of focal mechanism parameters of the principal stress axis and the regional tectonic stress field,and analyze the relationship between the spatial and temporal distribution of the consistency of focal mechanism parameters and strong seismicity.The analysis showes that several moderate- and small- earthquakes whose stress-release fields are consistent or approximately consistent with the regional stress field occur near the source region of the strong earthquakes,and strong earthquakes will occur in the low-value area and its fringe of the consistent parameters of the moderate- and small- earthquaqkes.
引文
成尔林,李桂芳,陈和川,等.1982.1976年四川省松潘—平武7.2级地震前后主压应力轴的方向特征[J].地震学报,4(2):15-19.
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胡新亮,刁桂苓,马瑾,等.2004.利用数字地震记录的振幅比资料测定小震震源机制解的可靠性分析[J].地震地质,26(2):347-354.
华祥文.1980.唐山强震前后北京、天津周围地区应力场的变化过程[J].地震学报,2(2):33-37.
阚荣举,刘租荫,王绍晋,等.1983.龙陵地区大震前后平均应力轴取向的时间变化[J].地球物理学报,26(6):38-47.
李幼铭,朱碚定,梁尚鸿,等.1983.层状介质中地震体波广义透射系数的计算[J].地球物理学报,(增刊):130-139.
梁尚鸿,李幼铭,束沛镒,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[J].地球物理学报,27(3):249-257.
林纪曾,蒋维强,李幼铭,等.1991.粤东闽南沿海小震震源参数的测定研究[J].地震学报,13(4):420-429.
许忠淮,刘玉芳,张郢珍.1979.京津唐张地区地震应力场的方向特征[J].地震学报,1(2):13-18.
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[J].地震学报,5(3):268-279.
阎明,赵仲和.1989.唐山地震前后京津唐张地区小震初动符号的时空分析[M].北京:地震出版社.
赵英萍,刁桂苓,高景春,等.2004.张北强余震前震源机制解的一致性特征[J].华北地震科学,22(1):1-4.
刁桂苓,于新昌.1980.唐山地震前后京、津、唐、张地区的综合断层面解[J].西北地震学报,2(3):39-47.
刁桂苓,于新昌.1982.海坨山地震前综合断层面解矛盾比的变化[J].地震,(5):16-17.
胡新亮,刁桂苓,马瑾,等.2004.利用数字地震记录的振幅比资料测定小震震源机制解的可靠性分析[J].地震地质,26(2):347-354.
华祥文.1980.唐山强震前后北京、天津周围地区应力场的变化过程[J].地震学报,2(2):33-37.
阚荣举,刘租荫,王绍晋,等.1983.龙陵地区大震前后平均应力轴取向的时间变化[J].地球物理学报,26(6):38-47.
李幼铭,朱碚定,梁尚鸿,等.1983.层状介质中地震体波广义透射系数的计算[J].地球物理学报,(增刊):130-139.
梁尚鸿,李幼铭,束沛镒,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[J].地球物理学报,27(3):249-257.
林纪曾,蒋维强,李幼铭,等.1991.粤东闽南沿海小震震源参数的测定研究[J].地震学报,13(4):420-429.
许忠淮,刘玉芳,张郢珍.1979.京津唐张地区地震应力场的方向特征[J].地震学报,1(2):13-18.
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[J].地震学报,5(3):268-279.
阎明,赵仲和.1989.唐山地震前后京津唐张地区小震初动符号的时空分析[M].北京:地震出版社.
赵英萍,刁桂苓,高景春,等.2004.张北强余震前震源机制解的一致性特征[J].华北地震科学,22(1):1-4.
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