Coda wave attenuation tomography in Northern Morocco

In this study we focused on seismic attenuation (1/ Q c) tomography in Northern Morocco. For this purpose, two different models are employed: The Single Backscattering model hypothesis of Aki and Chouet (1975) to calculate values of Coda Q (Q c) and the Back-projection technique of Xie and Mitchell (1990) to estimate lateral variation in Q c via a tomographic inversion. For this investigation, the Coda Q method is applied to a number of 94 local earthquakes with a magnitude between Ml=0.7 and Ml=4. The digital seismograms of these earthquakes were recorded during the year 2008 by both local temporary and permanent broadband seismic station network deployed in Northern of Morocco. The Q c quality factor values have been computed at central frequencies 0.75, 1.5, 3, 6 and 12 Hz. The lapse time windows are restricted to 30s in order to sample the earth's crust only. The Q c results indicate that strong frequency dependence follow a power law for the entire area. The preliminary results of seismic Coda Q c attenuation tomography shows a dependence at each frequency band, between seismic attenuation and the geology structure units in the study area, especially in the region of Al Hoceima and the eastern part of the Rif which are characterized by high attenuation values due to active faults area, while low attenuation values are seen in the west and the south of the Rif in high frequencies.