Iberian Peninsula crustal structure from surface waves dispersion

Abstract

Phase velocity of Rayleigh waves traveling from Toledo to Málaga have been determined from seven selected earthquakes. The direction of approach of the wave front in relation to the ground particle motion at the standard Spanish stations (Toledo and Málaga) and at Porto (Portugal) is discussed. Also these three Observatories are considered as a triangular array to determine the phase velocity through the lberian Peninsula region; this result is compared with the dispersion data determined by the two stations at Toledo and Málaga. Two similar crustal-mantle structures, named IB1 and IB2, have been obtained for this Region, by modifying the models Dorman 8021 and CAN-SD respectively, and by means of the partial derivatives of the phase velocity with respect to the parameters of the layers. Both models IB1 and IB2 are almost identical and their corresponding dispersion curves fit the data with an error less than 0.1 km/sec. The crustal thickness given by these structures is about 33 km. Group velocities of Love and Rayleigh waves from near earthquakes have been also studied. Some Algerian earthquakes yielded a dispersion curve for the arm of the Mediterranean Sea between Algeria and Spain. The curve appears almost typically oceanic.