Bilateral recursive restitution of true ground motion from near-field and far-field seismograms

Summary A two-sided recursive inverse filtering procedure, originally proposed by R. Vích, is used to restore the true ground motion from digital records of inertial electromagnetic seismographs. Numerical simulations of far-field and near-field P-wave seismograms are used to test the performance of the procedure and to derive criteria for recognizing successful restorations. The procedure is applied to seismograms of local microearthquakes as well as of teleseismic events, and the restored signals are compared with those obtained by causal (one-sided) inverse filtering. In all cases the two-sided approach proved to have fundamental advantages: a higher accuracy of the approximation of the true ground motion, a faster convergence to the best attainable approximation, a lower sensitivity to incoherent noise, and a more reliable discrimination between veracious and dubious results.