Inversion for seismic moment tensors combining translational and rotational ground motions

Abstract

We assess the potential of additional rotational ground motions to increase the resolution of the full seismic moment tensor and its centroid depth during waveform inversion. For this purpose, we set up a test case of a shallow, medium-sized strike-slip source. In two scenarios, one based on theoretical station distribution and the other based on real station distribution, we compare the results based on inversion of translational ground motion data only and based on both, translational and rotational ground motion data. The inversion is done with a Bayesian approach to overcome the drawbacks of deterministic approaches and provide a comprehensive quantification of uncertainties. Our results indicate that the resolution of the moment tensor can be increased drastically by incorporating rotational ground motion data. Especially, the usually problematic components Mxz and Myz as well as all components containing spatial derivatives with depth benefit most. Also, the resolution of the centroid depth is much better.