Open Access1–18 Hz L g attenuation in the Granada Basin (southern Spain)
Author(s) -
Miguel F.,
Ibáñez J. M.,
Alguacil G.,
Canas J. A.,
Vidal F.,
Morales J.,
Peña J. A.,
Posadas A. M.,
Luzón F.
Publication year - 1992
Publication title -
geophysical journal international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0956-540X
DOI - 10.1111/j.1365-246x.1992.tb00576.x
Subject(s) - attenuation , coda , scattering , geology , seismology , physics , optics
SUMMARY The attenuation of the L g waves for the Granada Basin has been analysed. This study has been done in the frequency domain, eliminating the influences of the source, the instrumental response and the local site response, using the Reverse Two‐Station Method (RTSM). The average Q Lg value for the whole region, obtained for all the paths is: Q Lg = (105 ± 25)∞ (0.93±0.14) . The average values of QL g determined for this region are lower than those corresponding to other areas of Spain, and are similar to those of coda‐ Q obtained using local coda and single scattering methods, for some determined focal depth and for some lapse times (50 and 70 s). Small differences of the attenuation are observed between paths that cross the central part and the edges of the basin. A detailed analysis showed that the E‐W and the N‐S directions have differences between attenuation values; in the E‐W direction Q 0 L g (the Q L g value at 1 Hz of frequency) is 131 ± 7 and in the N‐S one Q 0L g is 88 ± 21. The frequency dependence is similar to the average QL g value. These values may indicate that the attenuation of the Lg waves, at least for this region, may not be affected by only the anelastic dissipation, but also by scattering process. The N‐S direction is normal to the dominating fault systems and seems to provide a greater scattering effect than the E‐W direction.