THE VALENCIA TROUGH - CODA-Q

The coda-Q method has been applied to a set of earthquakes located in the Mediterranean region, between the Iberian Peninsula and the Balearic Islands (the Valencia trough), and recorded at the short-period seismographic station of Ebro (EBR), located in Roquetes (Tarragona), to obtain the anelastic quality factor Q of coda waves. The applied method uses a set of master curves taking into account the frequency-dependence of the coda-Q values. To determine the master curves used to obtain the coda-Q values, non-linear inversion techniques have been applied to the short-period instruments. The coda-Q values and the frequency-dependence obtained for the region seem to indicate that the southern part of the Valencia trough tends to attenuate the seismic energy in the same manner as the Betic System, and the northern part seems to present higher Q values than the southern one. This fact may indicate different Q structures in both regions. A good correlation is observed among the obtained coda-Q values, their frequency-dependence, and known coda-Q values and L(g) wave attenuation in the coastal region of the Mediterranean Sea.