Upper crust attenuation in the Basin and Range Province of Sonora, Mexico
Por:
Castro R.R., Villalobos-Escobar G.P.
Publicada:
1 ene 2021
Resumen:
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. © 2021, The Author(s), under exclusive licence to Springer Nature B.V.
Filiaciones:
Castro R.R.:
Departamento de Sismología, División Ciencias de la Tierra, Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE), Ensenada, Baja California 22860, Mexico
Villalobos-Escobar G.P.:
Facultad de Ingeniería “Arturo Narro Siller”, Universidad Autónoma de Tamaulipas, Tampico, Mexico
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