Two attempts of study of seismic source from teleseismic data by simulatedannealing non-linear inversion

Two seismic source studies using teleseismic data are performed by Simulate d Annealing (SA), a non-linear inversion method. The Very Fast Simulated An nealing (VFSA) algorithm is used and only teleseismic data are inverted. We have designed a fast and efficient way of multiple direct problem evaluati on, which is based on pre-calculating the elementary Green's function. Duri ng the process we set the values of the inversion control parameters (tempe rature, number of iterations) and modified the cooling schedule. In the cur rent version, the inversion seeks for the point source mechanism, the depth of the source, the scalar moment and the source time function (STF). The m ethod is applied to two earthquakes: 18 Nov. 1992 in Greece, M 5.9 and 14 S ep. 1995 in Mexico, M7.3. The calculation is performed on a simple 1D model of the structure. For the first earthquake the inversion recovered the sol ution fairly well; for the second the solution was less acceptable. However , we do not consider this fact to be a failure of the method, but a consequ ence of an inadequate model of the source and of the medium structure. A ca sual attempt of reliability determination was also performed; the obtained values of errors are reasonable, except for a few cases when the method fai led.