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Abstract

The acoustic radiative transfer theory is utilized to analyze the propagation of seismic energy in a heterogeneous and random medium, and can be modeled by Monte Carlo simulations. By repeating the simulations and adjusting the non-isotropic scattering and absorption coefficients, the layer-specific intrinsic and scattering attenuation can be determined. The Monte Carlo simulation considers ray tracing in a deterministic and acoustic 1-D model. To validate the code, synthetic tests were conducted and the results indicate that it is possible to resolve both frequency- and depth-dependent attenuation values. The code was then applied to observed seismograms along the Leipzig-Regensburg fault zone. The fault zone was divided into a northern and southern area and the attenuation of the crust was calculated between 3 and 33 Hz. Our results demonstrate that the upper crust exhibits different characteristics compared to the middle and lower crust, as the intrinsic attenuation is dominant in the upper crust and significantly lower in deeper areas where earthquakes occur. In the mantle, the northern and southern regions also differ, with the southern part displaying stronger attenuation due to higher temperature.