INTRINSIC AND SCATTERING SEISMIC-WAVE ATTENUATION IN THE CANARY-ISLANDS

The Canary Islands volcanic complex is studied in terms of coda wave a ttenuation. A multiple lapse time window method, based on the hypothes is of multiple isotropic scattering with uniform distribution of scatt erers, is applied to the available seismic data in order to obtain the intrinsic absorption (Q(i)(-1)) and the scattering attenuation (Q(s)( -1)) in the Canarian lithosphere. The analysis is performed for two hy pocentral distance ranges: from 0 to 80 km and from 0 to 140 km. Resul ts show that in both cases and for all the studied frequency bands (1- 2, 2-4, 6-8 and 8-10 Hz) intrinsic absorption dominates. The low albed os found in the region indicate the low degree of heterogeneity in the Canarian lithosphere at the scale length of the studied frequencies. On the other hand the coda attenuation (Q(c)(-1)) calculated on the ba sis of the single-scattering theory gives values near Q(i)(-1) for low frequencies and near the total attenuation (Q(t)(-1)) for high freque ncies. The degree of frequency dependence of the attenuation parameter s is strong in all cases. A correlation of the observed attenuation pa rameters with the geological evidence for a hotspot-type archipelago a nd with other geophysical studies is suggested.