Distribución de Q en una región del Pacífico > 90 M.A. a partir del análisis de los modos fundamental y superiores de las ondas de Rayleigh

Abstract

Vertical multi-mode analysis of Rayleigh waves in a region of the Pacific~ 90 M.y. leads to a Q_β^-1 distribution for this region up to a depth of the order of 500 km. Comparison of the obtained results in this study with a previous model for a region of the Pacific > 100 M.y. (Canas and Mitchell, 1978), indicate that the new model presents low Q_β^-1 values for depths between 200 km and 300 km. It seems also that values of the new model for depth larger than 300 km would be lower than the ones corresponding to the model of Canas and Mitchell (1978).The procedure has been the following: a) Determination of phase and group velocities of Rayleigh waves; b) corrections due to anelasticity applied to the velocity data; c) determination of the shear-velocity model by application of inversion methods to the velocity data corrected by the effects due to anelasticity; d) determination of the theoretical amplitude spectras corresponding to the fundamental and to the addition of the higher modes, and e) Q_β determination obtained from the comparison of the theoretical and observed spectras.