Frequency-dependent attenuation in the crust beneath Central France from Lg waves: Data analysis and numerical modeling
Frequency-dependent attenuation in the crust beneath Central France from Lg waves: Data analysis and numerical modeling
复制标题
Lg 波在法国中部地壳中的频率相关衰减：数据分析和数值模拟
DOI：
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发表时间：
1985
期刊：
影响因子：
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通讯作者：
M. Bouchon
中科院分区：
文献类型：
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作者：
M. Campillo;J. Plantet;M. Bouchon
摘要通过资料分析和理论模拟相结合的方法，对法国中部地壳中横波的品质因子进行了估算。测量是根据法国地震台网22个短周期垂直地震台站的18次地震的Lg波记录进行的。通过数值模拟计算了理想弹性模型中Lg波的几何衰减。从Lg波和地震噪声记录中评估了台站响应（包括场地效应）。Q已计算了一组11个频率之间的0.5和10赫兹，并已发现在形式Q = 290 * f 0.52，其中f是频率。数值模拟结果将Lg波的Q值解释为地壳内部Q值的平均值。能量随距离衰减的理论和实验符合得很好。Lg波对低Q带的敏感性不同，无论该带是与沉积物有关还是与下地壳中的散射有关。根据我们的实验结果，法国中部下地壳似乎与高Q值有关。
Abstract The quality factor of shear waves in the crust beneath Central France is evaluated by the combined use of data analysis and theoretical modeling. The measurement is made from Lg wave records of 18 earthquakes at 22 short-period vertical seismic stations of the French seismic network. The geometrical attenuation of Lg waves has been calculated through a numerical simulation in a perfectly elastic model. The station responses (including site effects) have been evaluated from Lg waves and from records of the seismic noise. Q has been calculated for a set of 11 frequencies between 0.5 and 10 Hz and has been found to be in the form Q = 290 * f 0.52 where f is the frequency. The numerical simulation leads to the interpretation of Q of Lg waves as the mean value of Q within the crust. Theoretical and experimental decay of energy with distance are in very good agreement. The Lg waves present a different sensitivity to a low Q zone whether this zone is associated with the sediments or with scattering in the lower crust. The lower crust beneath central France appears from our experimental results to be associated with high values of Q .