Spatial variation of coda wave attenuation in the AL Hoceima region (Earthquakes of 24 Frebruary 2004), Morocco

On 24th February 2004 a significant earthquake (Md = 6.4) occurred in the north of Morocco causing great damage in the vicinity of Al Hoceima region. This area is characterized by a complex faulting system as a result of compressional tectonic forces. Three short period stations are set in this area of interest and recordings from these stations were used in this study. In order to complete our knowledge of attenuation, 60 local earthquakes are recorded a few days after the great earthquake with magnitude Ml 2.6-5.0 to estimate seismic attenuation. For this purpose, we applied the single backscattering model of Aki & Chouet 1975 in the frequency range for 1 to 4 Hz. The study of coda waves was limited to a relatively short lapse time (10 Seconds) in order to sample the earth’s crust only .The values of Qc estimated for all the three stations show a strong frequency dependent relationship of the form Qc=Q0fn, where Q0 is Qc at 1Hz , and n represents the degree of frequency dependence , and reflect the level of crustal heterogeneities to varying degrees. The average frequency dependent attenuation relationship has been obtained which indicates that the attenuation is high in this region. Finally to conclude our work, the values of Q0 suggest that Al Hoceima area is highly heterogeneous and the n parameter indicates a meaning frequency dependence of Qc

Quality factor of seismic coda waves from earthquakes in northern Morocco

The main objective of this work is to analyze seismic attenuation (1/Qc) using a single backscattering model hypothesis of Aki and Chouet (1975). For this purpose, the recordings of 66 local earthquakes (epicentre distance < 100 km) during 2008 in Northern Morocco have been used with a magnitude (Ml ) less than 4. The Qc quality factor values have been computed at four central frequencies 0.75, 1.5, 3, 6 and 12 Hz and analyzed for two horizontal and vertical components for performing the average values. Four lapse time windows seconds from 30 to 60 duration with a difference of 10 seconds have been analyzed to study the lapse time dependence of Qc. We obtained a strong average frequency dependence follow a power law Qn=Q0fn where Q0 is Qc at 1Hz and n is the power of frequency dependent .The frequency dependent relationships obtained are Qc=(143.75±1.09)f(0.864±0.006) for the vertical component , Qc=(149.12±1.08)f(0.85±0.05) and  for the N component , and Qc=(140.42±1.81)f(0.902±0.04) for the E component. The values estimated of coda Q shows independent on the component of wave motion consistent with (Jen-Kuang Chung 2009 and Priyamvada Singh 2012 ), thus only one component sufficient to treat the attenuation in this region. The mean values of the estimated Qc of the vertical component vary from 76 (at 0.75) to 1147.6 (at 12 Hz) for 30  seconds coda window length, for 40 seconds coda window length Qc vary from 122.48 (at 0.75) to 1255 (at 12 Hz ) while for 50 seconds coda window length Qc vary from 141.4 (0.75) to 1420.8 (at 12 Hz ) . Similarly for 60 seconds coda window length Qc vary from 173.89 to 1495. The increase in Qc values with lapse time shows the depth dependence which agree with many studies. The results obtained with this model are presented and then compared to results from the literature

Spatial variation of coda wave attenuation using aftershocks of the Al Hoceima earthquake of 24 February, 2004, Morocco

Empirical research on the emotion disappointment has focused uniquely on disappointments produced by outcomes that are worse than expectations. Introspection suggests that in many cases persons instead of outcomes cause the disappointment. In the present study we therefore argue that the emotion word "disappointment" refers to two different emotional experiences, namely, outcome-related disappointment and person-related disappointment. Results from an empirical study support this distinction by showing that these two types of disappointment differ from each other and from anger and sadness with respect to appraisals and response types

Estimation of Coda Wave Attenuation in Northern Morocco

We studied the attenuation of coda waves and its frequency and lapse-time dependence in northern Morocco. We analysed coda waves of 66 earthquakes recorded in this region during 2008 for four lapse time windows of length 30, 40, 50, and 60 s, and at five frequency bands with central frequency in the range of 0.75–12 Hz. We determined the frequency dependent Q relation for the horizontal (NS and EW) and vertical (Z) component seismograms. We analyzed three-component broadband seismograms of 66 local earthquakes for determining coda-Q based on the single back-scattering model. The Q values show strong frequency dependence in 1.5–12 Hz that is related to high degree of heterogeneity of the medium. The lapse time dependence of Q shows that Q (Q at 1 Hz) significantly increases with lapse time that is related to the depth dependence of attenuation and hence of the level of heterogeneity of the medium. The average frequency-dependent Q(f) values are Q= (143.75 ± 1.09) f, Q= (149.12 ± 1.08) f and Q= (140.42 ± 1.81) f for the vertical, north–south and east–west components of motion, respectively. The frequency-dependent Q(f) relations are useful for evaluating source parameters (Singh et al. 2001), which are the key inputs for seismic hazard assessment of the region.Peer Reviewe