Comparison of Multiple Lapse Time Window Analysis and Qopen to determine intrinsic and scattering attenuation

Abstract

SUMMARYThis study compares the results of Multiple Lapse Time Windows Analysis (MLTWA) and full envelope inversion (Qopen) to determine intrinsic and scattering attenuation of the crust using the region around the central part of the Leipzig–Regensburg fault zone in Germany as an example. We use 18 of the region’s strongest earthquakes from 2008 to 2019 with a magnitude between 1.4 and 3.0 in the frequency band range between 3 and 34 Hz. The determined attenuation values of both methods are similar within their error bars. The inverse quality factors of the shear wave are relatively low compared to other regions, with values of 3.2 × 10−4 to 8.7 × 10−4 for $Q^{-1}_{i}$ and 1.4 × 10−4 to 2.8 × 10−4 for $Q^{-1}_{sc}$, respectively. As a by-product of Qopen, we also obtain the energy site amplification of the stations used in the inversion as well as source displacement spectra and moment magnitudes of the inverted earthquakes. Several combinations of inversion parameters were tested for MLTWA, with $Q^{-1}_{i}$ and $Q^{-1}_{sc}$ providing the lowest trade-off. Likewise, we investigated the influence of window length on the results of Qopen. We found a dependency of the results on the length, if the windows are shorter than 30 s. For longer time windows, the dependence disappears, and the result becomes independent of window length..