Reply to comments on “Separation of Qi and Qs from passive data at Mt. Vesuvius: A reappraisal of the seismic attenuation estimates” by Ugalde, A. and Carcolé, E.

Abstract

The paper by Del Pezzo et al. (2006), hereafter named DPBZ, deals with the estimate of the seismic attenuation in the high frequency range for the volcanic area of Mt. Vesuvius. In particular DPBZ use a method based on the fit of the observed local earthquake coda envelopes to the radiative transfer classical equation (see Sato and Fehler, 1998 for a wide and exhaustive review on this argument) in terms of the intrinsic attenuation and the scattering attenuation coefficients. Ugalde and Carcolé in their comment (hereafter named UC) discuss two points of DPBZ that we summarize here in their essence: (a) Two approximations of the exact solution of the 3-D radiative transfer model have been calculated, that discussed by Zeng (1991) – hereafter Z91 – expressed by Formula (5) of UC, and that by Paasschens (1997) – hereafter P97 – expressed by Formula (6) of UC. UC show that P97 is more accurate than Z91, which is instead used in DPBZ. (b) DPBZ obtain the separated estimates of intrinsic- and scattering-attenuation coefficients, respectively !i and !s, first stacking the normalized energy envelopes (starting at 2Ts lapse time) and then fitting the experimental data with the normalized (in the same way) theoretical curve. UC disagree with this procedure. Their opinion is that DPBZ should have inverted the single energy envelopes and then have averaged the results obtained. In the following we reply to points (a) and (b) in two separate sections.