福建古田水口水库M_L4.8级地震序列震源参数研究
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摘要
应用福建省区域数字地震台网观测记录到的古田水口水库ML4.8级地震序列的资料,在扣除地震记录数据中传播路径效应、台站场地响应和仪器响应后,采用Atkinson单地震、多台记录平均的反演方法计算震源参数,共计算了序列中的38个ML≥2.5级地震的震源参数。结果显示:地震矩与震级之间有较好的线性关系,统计关系式为logM0=1.08ML+9.63;建立了用ML震级估算矩震级MW的公式MW=0.72ML+0.387;其它的参数间虽有一定的相关性,但很难给出定量的关系。对地震序列应力降随时间发展的变化分析认为,在前震期水口水库区域存在应力加速积累的过程,有出现高应力降异常值的发生,临近主震时,应力降有所回调;最大余震后,应力降呈逐步衰减,未出现高异常值。
This Paper,based on the data regarding the ML4.8 earthquake sequence to Gutian Shuikou Reservoir recorded by the regional digital seismic network of Fujian,and after taking out the propagation path effect,site response and instrument response from the seismic records,works out the source parameters for 38 earthquakes(ML≥2.5) by adopting the inversion method of Atkinson,i.e.average over data recorded by several machines for a single earthquake.The calculation results show that favorable linear relation between the seismic moment and the magnitude is found,with the statistical relation of logM0=1.08ML+9.63;a formula to estimate the moment magnitude MW using the magnitude ML is established as MW=0.72ML+0.387;it is hard to give a quantitative relation among other parameters in spite of the certain degree of relevance.An analysis on the variation of stress drop of the earthquake sequence with time considers that,during the pre-earthquake period,there is an accelerated accumulation of stress in ShuiKou Reservoir area,with abnormally high value of stress drop,which is found with a callback when it approaches the main shock and declines gradually after the largest aftershock without any abnormally high value.
This Paper,based on the data regarding the ML4.8 earthquake sequence to Gutian Shuikou Reservoir recorded by the regional digital seismic network of Fujian,and after taking out the propagation path effect,site response and instrument response from the seismic records,works out the source parameters for 38 earthquakes(ML≥2.5) by adopting the inversion method of Atkinson,i.e.average over data recorded by several machines for a single earthquake.The calculation results show that favorable linear relation between the seismic moment and the magnitude is found,with the statistical relation of logM0=1.08ML+9.63;a formula to estimate the moment magnitude MW using the magnitude ML is established as MW=0.72ML+0.387;it is hard to give a quantitative relation among other parameters in spite of the certain degree of relevance.An analysis on the variation of stress drop of the earthquake sequence with time considers that,during the pre-earthquake period,there is an accelerated accumulation of stress in ShuiKou Reservoir area,with abnormally high value of stress drop,which is found with a callback when it approaches the main shock and declines gradually after the largest aftershock without any abnormally high value.
引文
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[6]邹振轩,李金龙,俞铁宏,王政,等.温州珊溪水库地震序列震源参数研究[J].华南地震,2007,27(4):11-18.
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[2]Atkinson G M,Mereu R F.The shape of ground motion attenuation curves in Southeastern Canada[J].BullSeism Soc Amer,1992,82(5):2014-2031.
[3]Moya C A,Aguirre J.Inversion of source parameters and site effects from strong ground motion records usinggenetic algorithms[J].Bull Seism Soc Amer,2000,90(4):977-992.
[4]Kanamori H..The energy release in great earthquake[J].J Geophys Res,1977,82(20):2981-2987.
[5]康英,郑斯华,刘杰,吕金水,等.中小地震震源参数的求解及其相似关系[J].华南地震,2004,24(2):11-21.
[6]邹振轩,李金龙,俞铁宏,王政,等.温州珊溪水库地震序列震源参数研究[J].华南地震,2007,27(4):11-18.
[7]韦士忠,李玉萍.大同地震前后介质Q值和小震震源参数的变化[J].地震,1992,(2):30-38.
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