Estudio del factor anelástico Q de la coda de los terremotos correspondientes a las regiones central y oriental del Eje Volcánico de México

Abstract

Using the coda of several earthquakes situated in Central and Oriental regions of the Volcanic Axis of Mexico, and recorded in the OXM seismographic station of the Servicio Sismológico Nacional, the foil m\ mg results have been obtained: a) Q is strongly frequency dependent in the form Q• Q0(f' f0)u, being the values of u• 0.4 for the Central re-gion and 0.6 for the Oriental one, "here f varies between 0.6 Hz and 1.0 Hz. b) Thc values of Q0 obtained for a reference freq uency of f0 • 1 llz are 322 fo r the Central region and 129 for the Oriental one. e) The 5-wave attenuation coefficients obtained are 0.0023 km-1 and 0.0102 km-1 for thc Central and Oricn· tal parts respectivcly. d) The coda excitation coefficients obtained are 3.56 x 10-25cm ~ dyne cm fo r thc Central rcg10n and 1.85 x ttf"cm s/dyne cm for the Oriental one. The above results may indica te a higher degree of faulting and/or a higher concentration of magmauc cham· bers under the Oriental region than under the Central one.