[S03-1] Imaging of heterogeneities in the Earth with seismic scattered waves and ambient noise I

[S03-1-06] Elastic vs. Acoustic Radiative Transfer Theory - Estimation of Seismic Attenuation Parameters in Germany

Peter J. Gaebler¹, Tom Eulenfeld^{1, 2}, ^○Ulrich Wegler² (1.BGR, Hannover, Germany, 2.Universitaet Jena)

In a first step a local data set is used to compare the outcomes of elastic and acoustic radiative transfer theory simulations. Frequency-dependent scattering and intrinsic attenuation parameters are estimated for the crustal structure beneath the W-Bohemia/Vogtland swarm earthquake region close to the border of Czech Republic and Germany using the two different modeling approaches. The parameter estimations are based on fitting synthetic envelopes to observed seismogram envelopes from shallow local events. The two different methods yield a very similar S-wave scattering and intrinsic attenuation model for the crustal structure in the Vogtland region with intrinsic attenuation being the dominant source of seismic attenuation. The similarity of the results indicates that for a simple half space setup, isotropic scattering and only modeling S-wave propagation, the acoustic approach suffices to obtain basic parameters about the attenuation properties of the medium. This is especially attractive, as analytic solutions to this approach exist, which can be computed efficiently and deliver results with only minor computational costs.
In a second step over 20 years of earthquake data from the German Central Seismological Observatory data archive is used to estimate the spatial dependent distribution of seismic intrinsic and scattering attenuation of S-waves for frequencies between 0.5 and 20 Hz in Germany using acoustic radiative transfer theory. We present preliminary results of the spatial distribution of intrinsic attenuation represented by the absorption path length, as well as of scattering attenuation in terms of the mean free path and compare the outcomes to results from previous studies. Furthermore catalog magnitudes are compared to moment magnitudes estimated during the inversion process.