Seismic network calibration for retrieving accurate moment tensors

We present a method for calibrating seismic networks in order to retrieve highly accurate seismic moment tensors. The method is based on a joint inversion of large datasets of earthquakes for moment tensors and for amplifications of the network stations, which encompass the instrumental amplifications of sensors and the gain factor of the acquisition system, as well as the local site effects neglected in modeling of Green’s functions. The method is capable of detecting the reverse polarity of sensors, incorrect orientation of sensors, or anomalous site effects caused by local geological conditions at individual stations. The robustness and accuracy of the method are tested on synthetic data with different noise levels, station configurations, and a variety of focal mechanisms. The numerical modeling confirms that the inversion code works well and yields robust results.