Modelo de fricción interna de las ondas de Cizalla para las placas Nazca-Cocos

Abstract

Inversion methods in the stochastic form were applied to attenuation coefficients of Rayleigh waves from the Nazca-Cocos plate in order to model internal friction of shear waves Q^-1_β for that region. The results suggest the possibility that in the upper mantle underneath the area there exists a zone of extremely high Q^-1_β a values (~19 x 10^-3). The lower limits of the Lithosphere and the Astenosphere for the region are found between 40 km and 200 km respectively. Comparison of the results of this work and those corresponding to an oceanic plate in the Pacific (0-50 m. a.) show that the younger the area the higher the internal friction. Moreover, the data available suggest that the thickness of such a zone decreases with the age of the Lithosphere. Results of this work agree with a previous study on internal friction for shear waves in plate of the Pacific Ocean.