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Zusammenfassung:
Recent progress in seismic instrumentation has opened new opportunities for using wavefield gradients (strain and rotation) for several seismic applications. We show that single-station six-component (6C) measurements, combining three translational and three rotational motions, can be used to investigate the shallow velocity structure. A remarkable advantage of this single-station 6C approach is its simpler way of deployment compared to array measurements, which especially eases the application in urban areas. We performed ambient noise measurements in Munich, Germany, using an iXblue blueSeis-3A rotational motion sensor together with a Nanometrics Trillium Compact seismometer. From the 6C data we were able to compute Love and Rayleigh dispersion curves, which are inverted together with H/V spectral ratios to obtain 1D P- and S-wave velocity profiles of the upper 100 m. The resulting velocity structure is implemented with additional geological and geophysical data into a 3D subsurface model. This model is used to perform 3D seismic simulations of induced earthquakes using the spectral element code SALVUS. The simulations help to quantify the amplification effect of the shallow low velocity sediments in the Munich area. In addition, the maximum ground motion and its spatial distribution can be estimated, which is important to evaluate the seismic risk in this densely populated area.
