We estimated the S-wave quality factor Q(f) of the upper crust in northeastern Sonora, Mexico, using a two-layer model. The first layer of the model has a thickness of 1 km, and the frequency dependence of Q can be represented by the relation Q(f) = 127f ^0.7 in the frequency range of 0.5 ≤ f ≤ 20 Hz. The second layer varies in depth between 1 and 21 km, and Q(f) = 181f ^0.7 in the same frequency range. The average Q of the model, weighted with the thickness of the layers, gives the relation Q(f) = 179.1f ^0.7. We used nonparametric attenuation functions, determined in a previous study, to correct the observed spectral amplitudes, and then we retrieved source and site effects using a spectral inversion scheme. We used the resulting functions to separate source and site effects from the original spectral records and modeled Q for the 1-D model’s depths. We analyzed 38 local earthquakes recorded by 12 stations of the regional network RESNES (Red Sísmica del Noreste de Sonora). We found that the S-wave Q of the superficial layer is a factor of only 1.4 smaller than the more profound layer. This result validates the use of an average Q to correct spectral amplitudes by the effect of anelastic attenuation from waves traveling within the upper crust.

我们使用两层模型估计了墨西哥索诺拉东北部上地壳的S波品质因子Q ( f )。该模型的第一层的厚度为1公里，对频率的依赖性Q可以通过关系来表示Q（˚F）= 127 ˚F  ^0.7 0.5≤的频率范围˚F ≤20赫兹。第二层的深度在 1 到 21 公里之间变化，在相同的频率范围内Q ( f ) = 181 f  ^0.7。模型的平均Q，用层的厚度加权，给出关系Q( f ) = 179.1 f  ^0.7。我们使用先前研究中确定的非参数衰减函数来校正观察到的频谱幅度，然后我们使用频谱反演方案检索源和站点效应。我们使用结果函数将源和站点效应与原始光谱记录分开，并为一维模型的深度建模Q。我们分析了区域网络 RESNES ( Red Sísmica del Noreste de Sonora )的 12 个台站记录的 38 次局部地震。我们发现浅层的S波Q仅比更深层小 1.4 倍。该结果验证了使用平均Q 通过在上地壳内传播的波的非弹性衰减效应来校正谱振幅。