江苏体应变数字台网地震尾波的衰减关系与震级
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摘要
体积式应变仪能记录全球大震,根据江苏体应变数字台网记录的全球大震波形,给出了测定地震尾波衰减系数、台网震级公式、震级标准差以及单台校正值的方法。由衰减经验关系lgA=G-klgτ导出的地震尾波应变双振幅A随尾波推移时间τ的衰减系数k=1.415,并取得以M(PEK)震级为基准的地震尾波应变台网震级公式MDC=4.02+1.04lgτ+0.74lgA±0.02,给出了江苏5个体应变台站的震级校正值,计算了近年内全球发生的35个地震震级值,平均震级标准差为0.11。尾波多点测量改善了7.6级以上大震MDC的精度,用该方法测量全球大震不存在震级"饱和"问题。
Volumetric strainmeters can record large earthquakes all over the world. Based on the waveforms of the large earthquakes all over the world recorded by the Jiangsu Digital Volumetric Strain Network, methods for determining the seismic coda's decay law, magnitude formula of the network, standard deviations of magnitudes and station correction values are given.Using these methods a value of 1.415 is obtained for the decay coefficient k in the empirical formula of lgA=G-klgτ, which characterizes the dieaway of the double amplitudes A of the seismic coda with the coda's elipse time τ(beginning from the Pwave on a short period seismograph). The following expression is obtained as the coda wave magnitude formula for the strain network taking the M(PEK) magnitude as magnitude standard: MDC=402+104lgτ+074lgA±002. The station correction values of magnitude are given for the five volumetric strain stations in Jiangsu Province. The magnitude values are calculated for 35 earthquakes occurring all over the world in the recent several years with an average standard magnitude deviation of 011.The accuracy of MDC determination for great earthquakes of magnitude above 76 is improved based on the multipoint measurement of coda waves. No magnitude saturation problem exists when this method is used to determine the magnitudes of great earthquakes all over the world.
Volumetric strainmeters can record large earthquakes all over the world. Based on the waveforms of the large earthquakes all over the world recorded by the Jiangsu Digital Volumetric Strain Network, methods for determining the seismic coda's decay law, magnitude formula of the network, standard deviations of magnitudes and station correction values are given.Using these methods a value of 1.415 is obtained for the decay coefficient k in the empirical formula of lgA=G-klgτ, which characterizes the dieaway of the double amplitudes A of the seismic coda with the coda's elipse time τ(beginning from the Pwave on a short period seismograph). The following expression is obtained as the coda wave magnitude formula for the strain network taking the M(PEK) magnitude as magnitude standard: MDC=402+104lgτ+074lgA±002. The station correction values of magnitude are given for the five volumetric strain stations in Jiangsu Province. The magnitude values are calculated for 35 earthquakes occurring all over the world in the recent several years with an average standard magnitude deviation of 011.The accuracy of MDC determination for great earthquakes of magnitude above 76 is improved based on the multipoint measurement of coda waves. No magnitude saturation problem exists when this method is used to determine the magnitudes of great earthquakes all over the world.
引文
[1] (加)GeorgeD.Garland著.陈 ,唐晓明,赵晓敏译.地球物理学引论(地幔、地核和地壳)[M].北京:地震出版社.1987.
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[5] 黄才中,陈 飞,殷 翔,等.面波的尾波衰减经验关系和震级[J].地震学刊,2000(2):15-22.
[2] 丁仁杰,黄才中.用苏03井水震图测定全球大地震震级的初步研究[J].地震学刊,1985(3):43-48.
[3] 黄才中,葛焕称,江铁鹰,等.中国东部的尾波衰减经验关系和震级[J].地震学刊,1995(1):1-8.
[4] 黄才中,丁仁杰,倪岳伟,等.中国东北地区尾波震级[J].地震,1994(3):29-38.
[5] 黄才中,陈 飞,殷 翔,等.面波的尾波衰减经验关系和震级[J].地震学刊,2000(2):15-22.
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