Abstract

Amplitude spectra of long-period surface waves are used, together with other seismological data, to reconstruct the seismic moment tensor of a point source. The problem of reconstruction is reduced to a set of nonlinear equations solved by iterative procedures. The medium between the source and the recording site is commonly considered as horizontally uniform, and the initial approximation of the seismic moment tensor is found from {\it a priori\/} information. Unlike this approach, we derive the set of equations for a medium formed by a system of uniform blocks and find the initial approximation from that data which are used in the basic iteration procedure. The source depth, assumed to be unknown, is found at this stage. Numerical tests were used to analyze the efficiency of the suggested algorithm. Particularly, we examined errors of reconstruction induced by incorrect representations of the medium near the source. Numerical tests show that nodal planes are stable enough, even under significant deviations of the parameters describing the medium. However, such deviations have a significant effect on the estimates of the scalar seismic moment tensor parameters.