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.

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.

Del Pezzo, E., Bianco, F., Zaccarelli, L., 2006. Separation of Qi and Qs frompassive data
at Mt. Vesuvius: a reappraisal of the sismic attenuation estimates. Phys. Earth
Planet. Interiors 159, 202–212.
Paasschens, J.C.J., 1997. Solution of the time dependent Boltzmann equation. Phys.
Rev. E. 56, 1135–1141.
Sato, H., Fehler, M., 1998. SeismicWave Propagation and Scattering in the Heterogeneous
Earth. Springer and Verlag, New York.
Zeng, Y., 1991.Compact solutions for multiple scatteredwave energy in time domain.
Bull. Seism. Soc. Am. 81, 1022–1029